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District

Laboratory

Practice in

Tropical

Countries

Part 1

Second Edition

Monica Cheesbrough

CAMBRIDGE UNIVERSITY PRESS

Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo

Cambridge University Press

The Edinburgh Building, Cambridge CB2 8RU, UK

First published in print format

ISBN-13 978-0-521-67630-4

ISBN-13 978-0-511-34935-5

Every effort has been made in preparing this book to provide accurate and up-to-

date information which is in accord with accepted standards and practice at the

time of publication. Nevertheless, the authors, editors and publisher can make no

warranties that the information contained herein is totally free from error, not least

ecause clinical standards are constantly changing through research and

regulation. The authors, editors and publisher therefore disclaim all liability for

direct or consequential damages resulting from the use of material contained in

this book. Readers are strongly advised to pay careful attention to information

provided by the manufacturer of any drugs or equipment that they plan to use.

2005

Information on this title: www.cambrid

e.or

/9780521676304

This publication is in copyright. Subject to statutory exception and to the

provision of relevant collective licensing agreements, no reproduction of any part

may take place without the written permission of Cambridge University Press.

Cambridge University Press has no responsibility for the persistence or accuracy

of urls for external or third-party internet websites referred to in this publication,

and does not guarantee that any content on such websites is, or will remain,

accurate or appropriate.

Published in the United States of America by Cambridge University Press, New York

www.cambridge.org

eBook

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iii
Part I
Contents
Chapter 1 Organization and stafﬁng of district laboratory services
1 Importance of laboratory practice in district health care . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pages 1 – 3
2 Structuring of a district laboratory network. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 – 9
3 Training and continuing education of district laboratory personnel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10–11
4 Code of conduct for laboratory personnel and status  of medical laboratory practice . . . . . . . . . . . . . . . . . . 11 –12
Chapter 2 Total quality management of district laboratory services
1 Ensuring a reliable and quality laboratory service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14–20
2 Selection of tests and interpretation of test results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20–28
3 Financing district laboratory services and controlling costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28–31
4 Quality assurance and sources of error in district laboratory  practice. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31–37
5 SIUnits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37–40
6 Guidelines for preparing stains and reagents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40–47
7 Communicating effectively. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47–48
Chapter 3 Health and safety in district laboratories
1 Implementing a laboratory health and safety programme. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50–56
2 Safe laboratory premise and personal safety measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56–59
3 Microbial hazards. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59–66
4 Decontamination of infectious material and disposal of  laboratory waste. . . . . . . . . . . . . . . . . . . . . . . . . . . . 66–74
5 Chemical and reagent hazards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75–87
6 Equipment and glassware hazards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87–89
7 Fire safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89–91
8 Emergency First Aid. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 –95
Chapter 4 Equipping district laboratories
1 Selection, procurement and care of equipment  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 –103
2 Power supplies in district laboratories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103–108
3 Microscope. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 –126
4 Equipment for purifying water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 –131
5 Equipment for weighing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 –133
6 Equipment for pipetting and dispensing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134–138
7 Centrifuges. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 –143
8 Laboratory autoclave . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143–148
9 Incubator, water bath, heat block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148 –152
10 Colorimeter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152–157
11 Mixers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158–160
12 General laboratory-ware for district laboratories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160 –175
Chapter 5 Parasitological tests
1 Parasitology in district laboratories and quality assurance of tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178–183
2 Features and classiﬁcation of parasites of medical importance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 –191
3 Direct examination of faeces and concentration techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191–200
4 Identiﬁcation of faecal protozoan trophozoites, cysts and oocysts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200–208

5 Identiﬁcation of helminth eggs and larvae found in fae ces. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209–235
6 Examination of urine for Schistosoma haematobium eggs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236–239
7 Examination of blood for malaria parasites. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239–258
8 Examination of blood, lymph ﬂuid, and c.s.f for trypanosomes causing African trypanosomiasis. . . . . . . 259–266
9 Examination of blood for Trypanosoma cruzi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266– 271
10 Examination of specimens for Leishmaniaparasites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271–279
11 Examination of blood for microﬁlariae in lymphatic ﬁlariasis and loiasis. . . . . . . . . . . . . . . . . . . . . . . . . . . 280 –291
12 Examination of skin for Onchocerca volvulusmicroﬁlariae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291–295
13 Examination of sputum for Paragonimuseggs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295–297
14 Less frequently needed tests:
Investigation of amoebic liver abscess . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 298–299
Investigation of primary amoebic meningoencephalitis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299–300
Diagnosis of toxoplasmosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300–302
Diagnosis of hydatid disease. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302–304
Examination of muscle tissue for Trichinella spiralis larvae. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304–305
Detection of Dracunculus medinensis (Guinea worm) larvae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305–306
Chapter 6 Clinical chemistry tests
1 Clinical chemistry in district laboratories  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310– 313
2 Quality assurance of clinical chemistry tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313–333
3 Measurement of serum or plasma creatinine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333–337
4 Measurement of serum or plasma urea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337–340
5 Measurement of blood or plasma glucose. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 340–349
6 Measurement of serum or plasma bilirubin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 349–355
7 Measurement of serum albumin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355–358
8 Measurement of serum or plasma alanine aminotransferase (ALT) activity . . . . . . . . . . . . . . . . . . . . . . . . 358–361
9 Measurement of serum or plasma alpha amylase activity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 360–364
10 Measurement  of sodium and potassium in serum or plasma. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 364–369
11 Urine  tests. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 369–385
12 Cerebrospinal  ﬂuid (c.s.f) tests. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 386–389
13 Faec al tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 389–392
Appendix I
Preparation of reagents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398– 412
Appendix II
Useful addresses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 414–420
Appendix III
Useful charts and ﬁgures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 425–428
Supplement
Planning a training curriculum for district laboratory personnel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 430–435
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 437–454
iv

Preface

Since the publication of the ﬁrst edition of Part 1 District Laboratory Practice in Tropical Countries the

essential role of the laboratory in providing a scientiﬁc foundation for district health care and improving the

quality of health care to communities, has not changed. The new challenges faced by health authorities

however, have led to changes in laboratory practice and a greater emphasis on the need for reliable well

managed district laboratories and their rational use in district health care.

In deciding the changes to be incorporated in the new edition of Part 1, the author and those who have

helped with the revision have been guided by the views and requests of those using the book in their work

and training programmes. The important chapters covering management, quality assurance, health and safety

and equipping of district laboratories have been reviewed and updated where needed. For those with internet

access and e-mail facilities, the details of equipment manufacturers now include website information and

e-mail addresses.

Information on parasitic diseases and their control has been brought up to date. Current knowledge on HIV

interaction with parasitic pathogens and new technologies to diagnose parasitic infections have been included.

Immunochromatographic tests to diagnose malaria have been described, their limitations discussed, and

information on the WHO malaria rapid diagnostic tests website included. Other parasite-related websites and

a list of up to date references and recommended reading are given at the end of the parasitology chapter.

Within the clinical chemistry chapter, the text covering diabetes mellitus has been revized to include the

current WHO classiﬁcation of diabetes and guidelines for diabetes diagnosis. Urine strip tests have also been

updated. To assist in monitoring HIV/AIDS patients for toxicity to antiretroviral drugs, a colorimetric test kit to

measure alanine aminotransferase (ALT) has been included where it is not possible to refer specimens for

testing to a regional clinical chemistry laboratory. Information is also given for a colorimetric creatinine test kit.

For many laboratory programmes, the introduction of standard operating procedures for laboratory tests

backed by quality assessment schemes has been key to improving the reliability, efﬁciency and accountability

of district laboratory services, motivating laboratory staff and increasing the conﬁdence of laboratory users.

Safe laboratory practices now followed in many laboratories have reduced work-related accidents and

laboratory-acquired infections. It is hoped that the new edition of Part 1 will continue to help those involved

in training and those working in district laboratories, often in difﬁcult situations. It is also hoped that it will

encourage health authorities to provide the resources needed to provide a quality laboratory service to the

community.

Monica Cheesbrough May 2005

Acknowledgements

Special thanks are due to all those working in laboratories in tropical and developing countries and those

involved in training laboratory personnel who have corresponded and contributed their suggestions for this

second edition of Part 1 District Laboratory Practice in Tropical Countries.

Gratitude is expressed to all those who have helped to prepare the new edition:

Mr Malcolm Guy, formerly Scientiﬁc Administrator MRC Laboratory in the Gambia, for reading through and

commenting on chapters covering the organization, management, safe working practices and equipping of

district laboratories.

Mr John Williams, Clinical Scientist, Department of Infectious and Tropical Diseases, London School of

Hygiene and Tropical Medicine, for helping to update the parasitology chapter.

Mr Anthony Moody, previously Laboratory Manager, Hospital for Tropical Diseases, London, for also assist-

ing in the revision of the parasitology chapter and for contributing text on rapid malaria diagnostic tests.

Professor Claus C Heuck, University Hospital, Duesseldorf, formerly of the World Health Organization Health

Laboratory Technology Unit, for reading through and making suggestions for the clinical chemistry chapter.

Mr Robert Simpson, Laboratory Manager, Chemical Pathology, St Thomas Hospital, London, for also assist-

ing in the revision of the clinical chemistry chapter.

Gratitude is also expressed to Dr Geoffrey V Gill, Reader in Tropical Medicine, Liverpool School of Tropical

Medicine, for updating the diabetes mellitus text.

Thanks are also due to Dr Peter Hill for commenting on quality assurance in clinical chemistry. The help of

Mr Ray J Wood, Laboratory Manager Mengo Hospital, Uganda, is also acknowledged.

The author wishes to thank Fakenham Photosetting for their careful and professional preparation of the new

edition.

Acknowledgements for colour artwork: These can be found on page 177 before Chapter 5 Parasitological

Tests.

Organization and stafﬁng of district

laboratory services

ORGANIZATION AND STAFFING OF DISTRICT LABORATORY SERVICES 1

1.1

1.1 Importance of laboratory

practice in district health care

District laboratory services have an essential role in

the surveillance, prevention, control, diagnosis and

management of diseases of greatest public health

importance. In discussing the role of laboratories at

district level, the World Health Organization com-

ments that with the scaling up of interventions

against HIV/AIDS, tuberculosis and malaria, the

need for diagnostic and laboratory services has

never been greater.

Meaning of district as used in this manual

The district is designated by the World Health Organization

as the key level for the management, growth and consoli-

dation of primary health care (PHC). It is the most

peripheral unit of local government and administration that

has comprehensive powers and responsibilities.

A typical rural district health system consists of:

 A network of PHC facilities, including village

health clinics, maternity centres, health centres

and small urban clinics. Mobile health units may

also provide some outreach PHC services and

support for home-based health care.

 A system for the referral of seriously ill patients

needing specialist care.

 The district hospital (ﬁrst referral hospital).

 Other government health related departments,

including social and rehabilitative services,

environmental health, nutrition, agriculture,

water supply and sanitation.

 Non-government health sector organizations

working in the district.

A district health system is usually administered by a

district health management team or health council,

consisting of representatives from the community,

PHC and hospital services, and health related

departments such as water and sanitation.

The growth of district health systems has led to:

– essential health services and health decisions

being brought closer to where people live and

work.

– communities becoming more aware of health

issues and demanding health services that are

relevant, accessible, reliable, affordable, and

accountable.

– district health councils being formed to identify

and assess community health care needs,

develop and manage local health services, and

ensure district health resources are used

effectively, efﬁciently and equitably.

Plate 1.1 Typical community-based district hospital in Kenya.

Plate 1.2 Health centre in Vietnam.

Courtesy: RP Marchand, MCNV.

WHY THE LABORATORYIS NEEDED IN DISTRICT

HEALTHCAR E

The laboratory has an important role in improving

the:

● quality,

● efﬁciency,

● cost-effectiveness,

● planning and management of district health care.

What difference can the laboratory make to

the quality of district health care?

 Laboratory investigations increase the accuracy of

disease diagnosis

Many infectious diseases and serious illnesses can

only be diagnosed reliably by using the laboratory.

For example, errors in the diagnosis of malaria have

been shown to be particularly high when diagnosis

is based on clinical symptoms alone.

Misdiagnosis or late diagnosis can lead to:

– incorrect treatment with misuse and waste of

drugs.

– increased morbidity and mortality.

– hospitalization and need for specialist care.

– patient dissatisfaction leading to negative

responses to future health interventions.

– underutilization of health facilities.

– lack of conﬁdence and motivation of health

personnel.

– increased risk to the community from inappro-

priate disease management and untreated

infectious disease.

 The laboratory has an essential role in screening

for ill health and assessing response to treatment

At district level the laboratory is needed to:

– assess a patient’s response to drug therapy.

– assist in monitoring the condition of a patient

and help to decide when it may be necessary to

refer for specialist care.

– screen pregnant women for anaemia, protein-

uria, and infections which if not treated may

cause disease in the newborn, premature birth,

low birth weight, or signiﬁcant maternal illness.

– screen the contacts of persons with infectious

diseases such as tuberculosis and sexually trans-

mitted diseases.

– detect inherited abnormalities such as haemo-

globin S as part of district family planning health

services.

– screen whole blood and blood products for

transfusion transmitted pathogens.

 The laboratory is needed to work with others in

reducing infection in the community and investi-

gating epidemics rapidly

The public health functions of a district health

laboratory service include:

– detecting the source(s) of infection, identifying

carriers, and contact tracing.

– participating in epidemiological surveys.

– assisting in disease surveillance and in the selec-

tion, application, and evaluation of control

methods.

– helping to control hospital acquired infections.

– participating in health education.

– examining designated community water supplies

for indicators of faecal and chemical pollution.

– responding rapidly when an epidemic occurs,

including appropriate on-site testing and the

collection and despatch of specimens to the

Regional or Central Microbiology Laboratory for

pathogen identiﬁcation.

In what ways can the laboratory contribute to

achieving efﬁciency and cost effectiveness in

district health care?

 The laboratory can help to reduce expenditure on

drugs

When the laboratory is used to improve the accu-

racy of diagnosis, perform appropriate antimicrobial

susceptibility testing, and monitor a patient’s

response to treatment:

– drugs can be used more selectively and only

when needed.

– patterns of emerging drug resistance can be

identiﬁed more rapidly and monitored.

 The laboratory can lower health care costs by

identifying disease at an early stage

Early successful treatment following early correct

laboratory diagnosis can help to:

– reduce the number of times a patient may need

to seek medical care for the same illness.

– prevent complications arising from advanced

untreated disease.

– avoid hospitalization and further costly investi-

gations.

 Signiﬁcant savings can be made when the labora-

tory participates in local disease surveillance and

control

This is because:

2 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

1.1

– the spread of infectious disease can be contained

more rapidly.

– disease control measures can be selected and

targeted more effectively.

– sources of infection and disease carriers can be

identiﬁed.

What information can the laboratory provide

to achieve rational health planning and good

health management?

 Reliable laboratory test results with relevant

patient data, provide information on the health

status of a community, health patterns, and

disease trends

This information is needed to establish health care

priorities and plan:

– health care programmes and location of health

facilities.

– training of district health personnel and delivery

of health services.

– treatment schedules and changes in drug usage.

– ﬁnancing of district health care programmes.

 Public health laboratory activities provide accurate

epidemiological information for health planning

This information can help to determine:

– causes of ill health in the community and risk

factors contributing to the presence and spread

of diseases.

– prevalence and incidence rates of important

infectious diseases.

– effectiveness of health care programmes, drug

treatments, and immunization programmes.

– which methods have appropriate sensitivity and

speciﬁcity to be useful.

Further information: Readers are referred to the paper of

Mundy et al: The operation, quality and costs of a district

laboratory service in Malawi.

1. 2 Structuring of a district

laboratory network

A district laboratory service must be integrated in

the health system which exists within its district if it

is to function as a network, be accessible, and pro-

vide a service that is needed by the community and

those managing health care in the district.

An example of a laboratory service that has been

integrated in a rural district health system is shown

in Fig. 1.1. The district laboratory service network

consists of:

 Outreach community-based laboratory facilities

located in:

– comprehensive health centres, st affed by

laboratory personnel and able to perform a

range of microscopical investigations and

other basic tests to assist in the diagnosis,

assessment, treatment and prevention of

common diseases.

– maternity health units, with nursing st aff

ORGANIZATION AND STAFFING OF DISTRICT LABORATORY SERVICES 3

1.1–1.2

SUMMARY

Laboratory practice in district health care

● District laboratories form an integral part of

good health care planning and delivery.

● Reliable, integrated, and well managed

district laboratory services are essential if:

– an accept able quality of community

health care and district health manage-

ment are to be achieved and sustained.

– illness and premature death are to b e

reduced.

– the community is to have conﬁdence in

its health services.

● Unless the importance of the laboratory in

generating valid and objective health data is

recognized:

– district health programmes will b e

unable to respond adequately to local

health care needs and priorities.

– sc arce health resources are likely to be

wasted on other less effective interven-

tions.

– national health planning will lack a

scientiﬁc foundation on which to

developand evaluate itshealth strategies.

● Fordistrict laboratories to operate effectively,

district health authorities must allocate the

correct proportion of available resources to:

– district lab oratory practice.

– training and continuing e ducation of

district laboratory personnel.

– instructing district me dical ofﬁcers and

community health workers in the

correct and optimum use of laboratory

services.

screening for anaemia and proteinuria and

collecting blood for appropriate antibody

screening in the district hospital laboratory.

 District hospital laboratory with facilities to service

the clinical, epidemiological, and training

requirements of a ﬁrst referral hospital.

 Specimen collection and transport system to

enable:

– patients attending health centres to b eneﬁt

from the facilities of the district hospital lab-

oratory.

– epidemics to b e investigated rapidly.

 Mobile laboratory work as required by district

health needs.

4 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

1.2

Fig. 1.1 Laboratory service network

CENTRAL

Hospital Laboratory

Public Health Laboratory

Specialist Laboratory Units

REGIONAL/PROVINCIAL

Hospital Laboratory

More clinical and public health

laboratory facilities

DISTRICT LABORATORY SERVICES

District

Hospital

Laboratory

Outreach

laboratories

Health centres

Maternity health

units

– meet the health needs of individuals and the

community.

– operate in an acceptable way.

– be accessible to the community and affordable.

– be reliable and sustainable.

Health centres with laboratory facilities are generally

better attended and more highly valued by the com-

munity because laboratory testing can often be seen

to establish the true cause of an illness, enabling

correct treatment to be prescribed at a patient’s ﬁrst

attendance.

Establishing a health centre laboratory

When deciding whether to site a laboratory in a

health centre the following are important consider-

ations:

 What is likely to be the affect on morbidity and

mortality in the area if essential laboratory facili-

ties were to be made available. How will the

results of tests be used?

 Is the health centre sufﬁciently well attended and

what is likely to be the demand for laboratory

tests?

 Is it possible to train local community health

workers to use laboratory facilities correctly, par-

ticularly in early diagnoses, follow-up, care, and

local disease surveillance?

Note:Written Guidelines on the Use of the Laboratory in

PHCmust be provided for community health workers by

the district medical ofﬁcer. Included in the Guidelines

shouldbe when to order particular tests, type of specimen

required,interpretation of testresults and appropriate fol-

low-up.Health workers should know the relative costs of

testsand average time it takes to perform individual tests.

 Is there a person trained or can be trained to per-

form the required tests competently and manage

safely and efﬁciently a health centre laboratory?

 Can the necessary measures be taken to ensure

the safe collection, transport and disposal of

specimens?

 Is it possible for the health centre laboratory to

be visited regularly by the district laboratory

coordinator or a senior person from the district

hospital laboratory?

Important:At no time should a laboratory be established

in a health centre unless it can be visited regularly and the

work controlled adequately.

 Is it possible to organize a reliable system for sup-

plying the laboratory with reagents and other

essential supplies?

 Is the cost of running the laboratory affordable,

including the cost of supplies, maintaining equip-

COMMUNITY-BASEDLABORATORY FACILITIES

A reliable community-based laboratory service is

one of the most important ways of improving the

quality of PHC and avoiding patients and pregnant

women having to travel to the district hospital for

essential laboratory tests. To be effective in PHC,

community-based laboratory practice must:

ment, and staff salaries? How will laboratory

expenditures be met?

 Can the health centre provide adequate facilities

for a laboratory to operate effectively and safely,

i.e. can a room be provided that is:

– structurally sound with se cure door(s), and

burglar proof, insect screened windows that

provide adequate light and ventilation.

– sufﬁciently large to b e sub-divided into areas

for working, reception of patients and speci-

mens, keeping records, decontamination of

infected material and cleaning of laboratory-

ware.

– provide d with running water.

– provide d with separate sinks for cleaning

laboratory-ware and hand-washing.

– ﬁtte d with facilities for the safe disposal of

specimens.

– wire d for mains electricity or if unavailable,

supplied with an alternative source of power,

e.g. battery, rechargeable from a solar panel.

– ﬁtte d with appropriate washable working

surfaces, seating for patients and staff, secure

storage cupboards, and shelving.

Stafﬁng a health centre laboratory

A laboratory in a community health centre will

usually be staffed by a laboratory worker or a local

community health worker trained to examine speci-

mens microscopically, perform appropriate diagnos-

tic and screening tests, collect and refer specimens

for specialist tests, and participate in community

health education and disease surveillance.

Depending on the workload of the health centre,

one or two laboratory aides may also be required.

Activities of a health centre laboratory

 To investigate by referral or testing on site, im-

portant diseases and health problems affecting

the local community. Depending on geographi-

cal area such investigations will usually include:

Bacterial and viral infections: Tuberculosis, lep-

rosy, meningitis, cholera, gonorrhoea, syphilis,

vaginitis, urinary tract infections, respiratory tract

infections, bacillary dysentery, and relapsing

fever. In the more comprehensive health centres

staffed by a laboratory technical ofﬁcer, it may

also be possible to investigate HIV disease and

associated infections.

Parasitic diseases: Malaria, schistosomiasis, lym-

phatic ﬁlariasis, loiasis, onchocerciasis, African

trypanosomiasis, Chagas’ disease, leishmaniasis,

amoebic dysentery, giardiasis, strongyloidiasis,

trichuriasis, hookworm disease, and any other

locally important parasitic diseases.

Other causes of ill health: Including anaemia, dia-

betes, renal disease, and skin mycoses.

 To assist the health worker in deciding the

severity of a patient’s condition and prognosis.

 To collect and refer specimens for testing to the

district laboratory, including:

– drinking water s amples from sources used

by the community.

– fae cal specimens for the microbiological

investigation of major enteric pathogens.

– serum for antib ody tests to investigate

important communicable diseases.

– spe cimens for biochemical testing to investi-

gate disorders of the liver and kidney,

metabolic and deﬁciency diseases.

– spe cimens for culture and antimicrobial sen-

sitivity testing to diagnose important bac-

terial infections and monitor drug resistance.

 To notify the district hospital laboratory at an

early stage of any result of public health import-

ance and send specimens for conﬁrmatory tests.

 To screen pregnant women for anaemia,

proteinuria and malaria, and refer serum to the

district hospital laboratory for antibody screening

of sexually transmitted diseases such as syphilis.

 To promote health care and assist in community

health education, e.g. by demonstrating micro-

scopically parasites of public health importance.

 To keep careful records which can be used by

health authorities in health planning.

 To keep an inventory of stock and order reagents

and other supplies in good time..

 To send an informative monthly report to the

district hospital laboratory of the work carried out

and results obtained.

Screening for proteinuria and anaemia in

maternity health centres

All health units providing antenatal care should be

able to test for proteinuria and anaemia. Laboratory

staff from the district hospital should train health

workers how to collect specimens correctly and how

to perform and control the required tests. Maternity

centres should be provided with standardized

reagents and specimen containers.

A reliable system is also needed for transporting

venousblood collected from antenatal women to the

district hospital laboratory for appropriate testing.

ORGANIZATION AND STAFFING OF DISTRICT LABORATORY SERVICES 5

1.2

DISTRICT HOSPITALLABORATORY

The important functions of a district health system

can be found in the 3rd edition, Principles of

Medicine in Africa.

Depending on the area served by the district

hospital, number of hospital beds, and workload of

the laboratory, the district hospital laboratory may

consist of a number of connecting laboratory units

or a subdivided laboratory room.

4,5

Staff

A district hospital laboratory is usually staffed by at

least one experienced laboratory ofﬁcer and de-

pending on workload, by two to four assistants and

several aides. Ideally the district laboratory coordina-

tor and tutor in charge of training should be based

at the district hospital.

Note: The training of district laboratory personnel is

described in subunit 1.3. The responsibilities of the

district laboratory coordinator and involvement of

the medical staff in district laboratory services are

discussed in subunit 2.1.

Activities of a district hospital laboratory

 In consultation with the district health manage-

ment team, public health ofﬁcers, and clinical

staff, to decide which laboratory tests are needed

and can be performed at district level (see sub-

unit 2.2).

 With the district laboratory coordinator, to man-

age effectively the district laboratory network as

explained in subunit 2.1.

 To prepare and implement standard operating

procedures for all district laboratory activities (see

subunit 2.4).

 To support the work of the outreach laboratories

by:

– testing spe cimens referred from community

health centres and maternity health units

and returning test results speedily.

– conﬁrming a test result that indic ates serious

illness or is of major public health import-

ance.

– supplying st andardized reagents, controls,

stains, specimen containers, stationery and

other essential laboratory supplies.

– che cking the performance of equipment.

– implementing and monitoring s afe working

practices.

– visiting each outreach lab oratory every three

months (role of the district laboratory coordi-

nator) to assist staff and monitor work per-

formance and quality of laboratory reports.

– training health centre lab oratory personnel

and arranging supervision and continuing

training in the work place.

– organizing a district external quality assess-

ment scheme as described in subunit 2.4.

 To refer specimens to the regional laboratory that

cannot be tested locally or are more economically

batch-tested at regional level. Also, to notify the

regional Public Health Laboratory of any result of

public health importance and to send specimens

for conﬁrmatory testing.

 To participate in external quality assurance pro-

grammes organized by the regional or central

laboratory.

 To keep accurate records and send a report

every three months to the district management

team and director of the regional laboratory,

detailing the activities of the district laboratory

network, together with suggestions for managing

problems and improving the laboratory service

to the community.

DISTRICT SPECIMEN COLLECTION AND TRANSPORT

SERVICE

An efﬁcient laboratory specimen collection and

transport service from the community health centres

with a reliable and prompt return of test results, is an

important way of extending laboratory facilities

throughout the district with the following beneﬁts:

– improved treatment and follow-up care of

patients in the community and better health care

of pregnant women.

– conﬁrmation and further investigation of patients

with important abnormal test results.

– more reliable information on health trends and

the causes of disease in the district.

– more rapid investigation and control of

epidemics.

– opportunities for detecting the emergence of

drug resistance and monitoring its spread in the

community.

Requirements of a specimen referral system

A specimen referral system will function reliably

providing:

 There is close communication between staff of

6 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

1.2

the community-based health facilities and the

district hospital laboratory.

 Outreach laboratories are supplied with speci-

men containers and laboratory request forms.

 Community health workers and district labora-

tory personnel are trained in the correct collec-

tion, preservation, and despatch of specimens.

 Correctly completed documentation accompa-

nies all specimens, and careful records are kept

of referred specimens and test reports.

 There is a reliable and secure means of trans-

porting specimens throughout the year and

returning test results with the minimum of delay.

MOBILE DISTRICT LABORATORYWORK

Basic mobile laboratory services may be required in

district health care for the following reasons:

– to support mobile community health pro-

grammes usually in areas where communities

are nomadic or sparsely distributed.

– to investigate outbreaks of serious disease and

identify high risk factors.

– to work with specialist teams to assess the effec-

tiveness of disease control interventions, check

the efﬁcacy of immunization programmes, and

obtain epidemiological data.

– to assist medical teams in emergencies and

disaster situations.

– to provide back-up for health education and the

promotion of health activities in the district.

– to monitor community water supplies for

pollution.

Mobile laboratory work must be well planned and

organized. Most of the difﬁculties and poor per-

formance associated with mobile laboratory work

are due to:

– using inappropriate technologies,

– equipment that is not sufﬁciently rugged or

designed for ﬁeld use,

– reagents that have deteriorated due to heat, high

relative humidity or incorrect storage,

– bypassing quality control proce dures because

they are too time-consuming or difﬁcult to apply

under ﬁeld situations.

Problems of safety arise when specimens are col-

lected and transported in unsuitable and leaky con-

tainers, handled without due care, or disposed of

unsafely. Accidents tend to occur more frequently

under ﬁeld conditions due to cramped, unfamiliar or

noisy working conditions, unsafe pipetting, limited

facilities for handwashing, tiredness, pressure to

work rapidly, and lack of supervision.

The cost of mobile laboratory work can be high

because in addition to transport costs, heat-sensitive

reagents deteriorate more rapidly, equipment needs

to be repaired more often, and extra controls are

needed in ﬁeld work. The travelling time of staff

needs also to be considered.

Recommendations for mobile district

laboratory work

 Establish the reasons and objectives for under-

taking mobile laboratory work and the anticip-

ated extent of it. Discuss the data required and

how it should be obtained and recorded.

 Assess whether full ﬁeld-testing is necessary or

whether specimens can be collected, stabilized,

and brought back to the district hospital labora-

tory for testing under more controlled conditions.

 Obtain in advance as much information as poss-

ible about travelling time and conditions, the

community and its customs, location of the work,

electricity supplies, water availability and quality.

 Select technologies and instrumentation of

proven reliability and acceptability in the ﬁeld. If

this cannot be established, pretest the techniques

and equipment under simulated ﬁeld conditions.

 Decide how to check the performance of instru-

ments and test for reagent deterioration under

ﬁeld conditions.

 Make a detailed check list of every item needed

and quantity of each required. Prepare rugged

containers for transporting the mobile laboratory,

including insulated containers for storing heat

sensitive reagents, controls, and specimens.

 Discuss in advance the tasks that each member

of the mobile laboratory team will perform and

measures to be taken to ensure quality and

safety.

 Monitor the cost, information provided, beneﬁts

to the community and performance character-

istics of any on-going mobile laboratory work.

Note: Further information on mobile laboratory

work can be found in the WHO publication Health

laboratory facilities in emergency and disaster

situations.

ORGANIZATION AND STAFFING OF DISTRICT LABORATORY SERVICES 7

1.2

8 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

1.2

PUBLIC HEALTH

Diagnosis

● More accurate with fewer

misdiagnoses.

● Earlier diagnosis.

Treatment

● Correct treatment with drugs

used selectively.

● Less over-prescribing.

● Side effects and progress

monitored.

Assessment/screening

● Is referral required?

● Pregnant women screened

for illhealth.

● Donor blood screened for

pathogens.

Epidemics

● Earlier pathogen

identiﬁcation.

● Earlier containment.

Surveillance/control

● More effective.

● Disease carriers identiﬁed.

● Contacts traced.

● Water supplies tested.

Health information

● Causes of disease.

● Sources of infection.

● Risk factors.

● Prevalence and incidence

rates.

PATIENT CARE

● Improvement in the quality of care with:

– acute illness more rapidly diagnosed,

– less preventable advanced/chronic illness,

– reduced mortality.

● Reduced transmission of infectious diseases.

● Lower expenditure on drugs.

● More efﬁcient use of health resources.

● Better health planning and management.

● Greater patient satisfaction.

● Greater motivation of health workers.

OUTCOME

DISTRICT

LABORATORY

PRACTICE

➡

Fig. 1.2 Role of the laboratory in district health care.

➡

ORGANIZATION AND STAFFING OF DISTRICT LABORATORY SERVICES 9

1.2

1 District hospital laboratory ofﬁcer.

Acknowledgements:Plate 2: Courtesy TALC, Plates 4,5, 6: Courtesy Warren L Johns, Plate 3:Courtesy Graham Mortimer.

2 Urinary schistosomiasis survey.

4 Staining for AFB in refugee camp.

3 Examining malaria smears in a

health centre.

5 Screening for anaemia in refugee camp.

6 Mobile laboratory work in Peru.

1. 3 Training and continuing

education of district laboratory

personnel

In most developing countries the training of medical

laboratory personnel is changing in response to:

 The need for more appropriately trained district

laboratory staff to support community-based

health care.

 The need for improved quality, safety, efﬁciency

and management in district laboratory practice to

optimize the use of health resources.

 The need for relevant, better planned, indige-

nous training programmes with educational

objectives that deﬁne clearly what trainees need

to learn to become competent district laboratory

ofﬁcers.

 The need for continuing on-site training and

education to retain competency and motivation.

A job related approach to the training and continu-

ing education of laboratory personnel is essential if

district laboratories are to provide a service that is

reliable, cost-effective, efﬁcient, and relevant.

Inappropriate or inadequate training of laboratory

personnel is not only wasteful but also potentially

dangerous.

The following are some of the indicators of poor

training of laboratory personnel:

– increase in the number of wrong test results.

– delays in issuing reports or loss of reports.

– frequent and serious complaints from those re-

questing laboratory tests and an increase in

requests for repeat tests as conﬁdence decreases.

– increase in the damage to equipment.

– increase in the contamination of reagents and

materials and in the amounts of reagents used.

– greater incidence of laboratory-acquired infec-

tions and other laboratory-related accidents.

– poorly motivated staff and job dissatisfaction.

– more time needed to supervize new staff.

– increase in laboratory operating costs.

Agood learner-centred training programmewill help

studentsto learn the right facts, skills,and attitudes in

an efﬁcient andinte grated way.It will assess whether

students have learned the right things and help

students to put intopractice what they have learned.

The training programme should allow sufﬁcient time

10 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

1.3

both for learning and assessment. Students and

tutors need to be assured of progress during train-

ing. Becoming aware of learning problems or teach-

ing inadequacies at the end of training is too late.

OB RELATEDTRAINING CURRICULUM FOR DISTRICT

LABORATORYPERSONNEL

A job related training programme is usually referred

to as competency-based or task-orientated and is

recommended for the basic training of medical lab-

oratory personnel. It is ideally suited to the training

of district laboratory ofﬁcers in developing countries

because it ensures the training is indigenous and rel-

evant to the working situation. It ﬁts a person to do

the job that is needed, where it is needed, and to

take on the responsibilities that go with the job.

The better a person can do their job the greater will

be their effectiveness and satisfaction. Competency

and job satisfaction are major factors in achieving

and retaining quality of service.

How to design a curriculum for district labora-

tory personnel

Information on how to design and implement a job-

related, i.e. competency-based, training programme

can be found in a SUPPLEMENT at the b ack of this

book, see pages 430–435.

Teaching students

● The purpose of a training programme is to

teach students to do a job.

● Teachers should concentrate on essential

facts, skills, and attitudes. It is neither

possible nor desirable to teach everything.

● Teachers should base their teaching on the

health problems of the community and on

the work their students will be expected to

do.

● Teachers should plan courses and lessons

using situation analysis and task analysis

(see Supplement, Training curriculum

for district laboratory personnel, pages

430–435.

Important: If students can do their job com-

petently at the end of their training, the course

has been successful. If students cannot do the

work they have been trained for, then the

course has failed.

CONTINUINGEDUCATIONOF DISTRICTLABORATORY

STAFF

Continuing professional education with support in

the workplace are required to retain the competence

and motivation of district laboratory staff and pre-

vent a decline in working standards. It is also an

effective way of promoting job satisfaction and

personal development.

Practising laboratory ofﬁcers have a professional

responsibility to participate in continuing education.

Continuing professional education is also necessary

for the successful introduction of new technologies

and the implementation of changes in standard

operating procedures.

Continuing education and updating of district

laboratory staff is best provided on-site by the district

laboratory coordinator during regular visits (see sub-

unit 2.1). On-going training in the workplace is also

one of the most effective ways of upgrading the

knowledge, attitudes, technical and management

skills of a laboratory worker who may have received

only a semi-formal training some years before. Use

of continuing education in this situation is often

referred to as ‘closing the performance gap.’

Value of Newsletters

A further way of promoting continued professional

development at district level is to circulate a simple

District Laboratory Newsletter which has an edu-

cation section contributed by qualiﬁed laboratory

personnel and district medical ofﬁcers. Laboratory

workers should be encouraged to stimulate dis-

cussion about their work. Such a Newsletter could

also circulate information about new advances in

laboratory practice relevant to community health

care and disease control.

For those countries with a Medical Laboratory

Association, laboratory personnel will usually be able

to continue their professional education through

their Association’s journal/newsletter and by attend-

ing refresher courses, seminars, and professional

meetings organized by their Association.

Upgrading and career development

For all laboratory personnel there should be oppor-

tunities for upgrading and career development

according to an individual’s abilities, participation in

continuing education, work responsibilities, and the

stafﬁng needs and structure of the indigenous

laboratory service.

Stafﬁng of a laboratory service must be based on

national health needs, organization of national

health services, and ﬁnance available for operating

the service and staff salaries.

The career structure should be ﬂexible to allow

for future development. Career prospects should be

sufﬁciently attractive to discourage trained district

laboratory personnel leaving the health service and

laboratory profession.

Note: The employment of district laboratory staff,

contracts of employment, and supervision of newly

appointed staff are discusssed in subunit 2.1

Ensuring a reliable and quality laboratory service.

1. 4 Code of conduct for

laboratory personnel and status

of medical laboratory practice

A Code of Professional Conduct for Medical

Laboratory Personnel should include those practices

and attitudes which characterize a professional and

responsible laboratory ofﬁcer and are necessary to

ensure a person works to recognized standards

which patients and those requesting laboratory

investigationscan expect toreceive. It alsoemphasizes

the professional status of medical laboratory

practice.

Adopting a Code of Professional Conduct helps

to remind district laboratory personnel of their

responsibilitiesto patients,duty to upholdprofessional

standards, andneed to work with complete integrity.

Note: A suggested Code of Professional Conduct for

medical laboratory personnel is shown on p. 12.

STATUSOF MEDICAL LABORATORY PRACTICE

Recognition by health authorities of the importance

of medical laboratories in health care programmes is

key to the development and adequate resourcing of

laboratory practice and to laboratory services

becoming more accessible to the community.

Such recognition is most successfully achieved

when:

 A Director of Medical Laboratory Services is

appointed and is effective in deﬁning clearly lab-

oratory services in the Ministry of Health and

collating laboratory data to demonstrate the

essential role of laboratory services in epidem-

iology, diagnosis and treatment of disease, health

planning, and management of health resources.

ORGANIZATION AND STAFFING OF DISTRICT LABORATORY SERVICES 11

1.3–1.4

 District medical ofﬁcers become more involved

in developing laboratory policies and supporting

district laboratory personnel.

 Medical laboratories:

– are ade quately staffed by competent and

well motivated personnel.

– are manage d and networked efﬁciently.

– follow a professional code of practice which

incorporates standard operating procedures

(SOPs).

– provide a service that is reliable, consistent,

relevant, and accountable.

 A national Association of Medical (Biomedical)

Laboratory Sciences is formed.

ATIONAL ASSOCIATIONOF MEDICAL (BIOMEDICAL)

LABORATORYSCIENCES

The following are the important functions of an

Association of Medical Laboratory Sciences:

– to discuss with health authorities the activities

and requirements of laboratories at district,

regional, and central level.

– to promote national le gislation regarding the

professional registration of laboratory per-

sonnel and certiﬁcation of laboratories to

practice.

– to discuss with health authorities: lab oratory

training, supervision of trainees, continuing

education, stafﬁng needs, employment,

working conditions, levels of remuneration,

and career development of qualiﬁed labora-

tory ofﬁcers.

– to organize lab oratory training and qualiﬁca-

tion, set professional standards, inspect lab-

oratories, assess the appropriateness of new

technologies, and provide professional

support and continuing education.

– to est ablish links with laboratory associations

in other countries and with the International

Association of Medical Laboratory

Technologists (IAMLT).

A professional laboratory association can only

function with the active support of its members.

An inexpensive, informative news sheet produced

quarterly can help to retain the interest of members

and increase the status of the medical laboratory

profession, particularly if health ofﬁcials and medical

ofﬁcers are invited to contribute articles.

12 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

1.4

Code of professional conduct for medical laboratory personnel

● Be dedicated to the use of clinical laboratory science to beneﬁt mankind.*

● Place the well-being and service of patients above your own interests.

● Be accountable for the quality and integrity of clinical laboratory services.*

● Exercise professional judgement, skill, and care while meeting established standards.*

● Do not misuse your professional skills or knowledge for personal gain, and never take anything from

your place of work that does not belong to you.

● Be at all times courteous, patient, and considerate to patients and their relatives. Safeguard the

dignity and privacy of patients.*

● Do not disclose to a patient or any unauthorized person the results of your investigations and treat

with strict conﬁdentiality any personal information that you may learn about a patient.

● Respect and work in harmony with the other members of your hospital staff or health centre team.

● Promote health care and the prevention and control of disease.

● Follow safe working practices and ensure patients and others are not put at risk. Know what to do

should an accident or ﬁre occur and how to apply emergency First Aid.

● Do not consume alcohol or take unprescribed drugs that could interfere with your work performance

during laboratory working hours or when on emergency stand-by.

● Use equipment and laboratory-ware correctly and do not waste reagents or other laboratory supplies.

● Strive to improve professional skills and knowledge and adopt scientiﬁc advances that beneﬁt the

patient and improve the delivery of test results.*

● Fulﬁll reliably and completely the terms and conditions of your employment.

*Taken from the Code of Ethicsof the International Association of Medical Laboratory Technologists.

REFERENCES

1 Laboratory services at the district level. World Health

Organization, Department of Essential Health

Technologies, 2003, p. 1–4. Website www.who.int/eht (to

be found under EHT Advocacy folder)

2 Mundy CJF et al. The operation, quality and costs of a

district hospital laboratory service in Malawi.

Transactions Royal Society Tropical Medicine and

Hygiene, 2003, 97, pp. 403–408.

3 Parry E et al. Principles of Medicine in Africa, 3rd edition,

2004. Cambridge University Press. Low price edition is

available.

4 Manual of basic techniques for a health laboratory. World

Health Organization, Geneva, 2nd edition, 2003, pp.

11–12.

5 Essential medical laboratory services project, Malawi

1998–2002, Final Report. Malawi Ministry of Health,

Liverpool School of Tropical Medicine, DFID.

Obtainable from HIV/AIDS Dept, Liverpool School

Tropical Medicine, Pembroke Place, Liverpool, L3 5QA,

UK.

6 Health laboratory facilities in emergency and disaster situ-

ations.World Health Organization, 1994 (WHO Regional

Publications Eastern Mediterranean Series No. 6).

Obtainable from WHO Regional Ofﬁce, Abdul Razzak,

Al Sanbouri Street, Po Box 7608, Nasr City, Cairo, 11371,

Egypt.

7 Abbatt F, McMahon R. Teaching health care workers –

Practical guide, Macmillan publication, 2nd edition, 1993.

8 McMinn. Design of basic training for laboratory tech-

nicians. Developing Country Proceedings 17th Congress

International Association of Medical Laboratory

Technologists. Stockholm, 1986, pp. 176–188 (no longer

in print).

RECOMMENDED READING

Carter, JY and Kiu OJ. Clinicians’ Guide to Quality

Outpatient Diagnosis. A Manual for Tropical Countries,

AMREF, Kenya, 2005.

Manual of basic techniques for a health laboratory. World

Health Organization, Geneva, 2nd edition, 2003.

Lewis SM. Laboratory practice at the periphery in developing

countries. International Journal Haematology, 2002, Aug 76,

Supplement 1, pp. 294–298.

Essential medical laboratory services project, Malavi

1998–2002. Final Report. Malawi Ministry of Health,

Liverpool School of Tropical Medicine, DFID. For avail-

ability, see Reference 5.

Carter JY, Lema OE. Practical laboratory manual for health

centres in eastern Africa, Nairobi, 1994. African Medical and

Research Foundation, PO Box 30125, Nairobi, Kenya.

Bedu-Addo G, Bates I. Making the most of the laboratory. In

Principles of Medicine in Africa, 2004, pp. 1326–1329.

Cambridge University Press (available in low price edition).

WEBSITES

www.who.int/eht

This is the WHO website for the Department of Essential

Health and Technologies (EHT). It was established in 2002,

out of what was formerly the Dept of Blood Safety and

Clinical Technology (BCT). Laboratory technology is one

of the eight areas that come under the new EHT department.

A document entitled Laboratory services at district level can

be accessed from the website under EHT, Advocacy folder.

This outlines how to provide safe and reliable district labora-

tory services through a WHO Basic Operational Framework.

www.phclab.com

This website has been established by Gabriele Mallapaty to

assist primary health care laboratory workers in developing

countries. It carries news features, information on training,

total quality management (TQM), equipment resources, and

carries links to other relevant websites.

ORGANIZATION AND STAFFING OF DISTRICT LABORATORY SERVICES 13

1.4

Total quality management of district

laboratory services

14 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

2.1

2.1 Ensuring a reliable and

quality laboratory service

A reliable and quality laboratory service is achieved

and sustained not just by implementing quality

control of laboratory tests. This is important but only

part of what is needed. Increasingly the term total

quality management (TQM) is being used to

describe a more comprehensive and user-orientated

approach to quality. TQM addresses those areas of

laboratory practice that most inﬂuence how a lab-

oratory service functions and uses its resources to

provide a quality and relevant service.

Such a comprehensive commitment to quality is

essential to achieve:

– best possible service to patients,

– user conﬁdence,

– effectiveness and efﬁciency,

– accountability,

– optimal use of resources.

Successful TQM of district laboratory services re-

quires close collaboration between laboratory staff,

those who request laboratory tests, district laboratory

coordinator, district hospital medical ofﬁcers, and the

district health management team.

ORRECT USE OF THE LABORATORY IN DISTRICT

HEALTHCAR E

Using the laboratory correctly in district health care

involves:

 Selecting those investigations that are needed in:

– curative health c are to establish or conﬁrm a

diagnosis, assess a patient’s condition and

prognosis, and monitor progress during

treatment,

– disease surveillance and the rapid investi-

gation of epidemics,

– health prote ction, health promotion, and

health education,

– health planning.

Note: Guidelines on the selection of laboratory

investigations and methods can be found in subunit

2.2.

 Deciding whether those investigations that are

needed can be:

– afforde d,

– reliably performe d in district laboratories (see

Laboratory considerations in subunit 2.2).

 Assessing whether those requesting laboratory

tests have sufﬁcient training and experience to:

– order diagnostic tests and epidemiologic al

laboratory investigations appropriately,

Total quality management in district

laboratory practice

TQM includes the following:

● Correct use of the laboratory in district

health care.

● Providing a quality service to patients and

those requesting tests.

● Management of ﬁnances, equipment, and

supplies.

● Stafﬁng of district laboratories, training and

competence of staff.

● Quality assurance to obtain correct test

results.

● Responsibility for TQM.

● Continuing improvement in quality.

TQM incorporates both the technical aspects of

quality assurance and those aspects of quality that

are important to the users of a laboratory service,

such as information provided, its correctness and

presentation, time it takes to get a test result, and the

professionalism and helpfulness of laboratory staff.

– underst and the meaning of test results and

the limitations of laboratory tests (see sub-

unit 2.2).

– use lab oratory data appropriately.

 Reviewing the value of tests performed so that:

– re dundant, out-dated tests become replaced

by tests that are more cost-effective, rapid,

informative, and easier to perform in district

laboratories,

– new appropriate te chnologies are introduced

in response to changes in disease patterns,

district health priorities, and treatment of

diseases.

 Monitoring the impact and cost-effectiveness of

district laboratory practice.

TOTALQUALITY MANAGEMENT OF DISTRICT LAB ORATORY SERVICES 15

2.1

PROVIDING A Q UALITY SERVICE

Understanding and responding to the needs and

expectations of patients and those requesting

laboratory tests are key components of TQM.

If users of district laboratories are to receive a

quality service, the service provided must be:

– Reliable and accountable: with tests performed,

using standard operating procedures (SOPs),

competently under routine and emergency

conditions and reports issued ‘on time’.

– Accessible and available: through a network of

health centre laboratories and an efﬁcient

specimen collection and transport system.

– Professional: by laboratory staff knowing their

job, presenting clear and informative reports, and

respecting patient conﬁdentiality.

– User friendly: by laboratory staff communicating

courteously, informatively, and patiently, particu-

larly when the workload is high and the labora-

tory is being pressed for test results.

– Dependable: by laboratory staff arriving at work

on time, not being absent unnecessarily, and not

allowing tests to be discontinued because

reagents have not been ordered correctly or in

good time, or equipment has failed because

preventive maintenance has not been carried out

or replacement parts ordered.

– Flexible: to allow for the introduction of new

technologies in response to the needs of users

and changing health care strategies.

MANAGEMENTOF FINANCES, EQUIPMENT, AND

SUPPLIES

Good management of laboratory ﬁnances, equip-

ment and supplies are important functions of TQM.

Managing laboratory ﬁnances

The training of district laboratory ofﬁcers must

include accountancy skills and how to keep accurate

records of requisitions, expenditures and income.

The ﬁnancing of district laboratory practice,

estimating laboratory operating costs, and ways of

controlling laboratory expenditure are discussed in

subunit 2.3.

Managing laboratory equipment

Lack of an effective equipment management policy

is a major cause of:

 District laboratories being under-equipped or

supplied with inappropriate equipment.

Evaluating district laboratory practice

● Ask the views of those requesting laboratory

tests and enquire how the laboratory is

understood and rated by the community.

● Find out whether those health centres with

laboratories are better attended than those

without laboratory facilities.

● Review district morbidity and mortality data

and how laboratory tests have been used in

patient diagnosis and management.

● Assess whether the causes of illhealth, such

as ‘fever’ are being better diagnosed when

the laboratory is used.

● In areas with access to laboratory facilities,

determine whether there are fewer patients

presenting with complications resulting

from incorrect and late diagnoses.

● Assess whether drug prescribing patterns

are different in those health centres with

laboratory facilities, particularly whether

drugs are being used more selectively with

fewer antimicrobial and antimalarial drugs

being prescribed.

● Evaluate the extent to which district labora-

tory practice helps to deﬁne health priorities,

detect disease carriers, identify those at

greatest risk, and improve the local man-

agement of epidemics.

● Review operating costs and whether oppor-

tunities exist for greater efﬁciency.

● Assess whether laboratory practice is help-

ing to target district health resources more

effectively.

 Equipment being purchased incorrectly, often

without a User Manual and essential replacement

parts.

 Equipment failure due to laboratory staff not

being trained to use and care for equipment

correctly, and damage to equipment due to

unstable electricity supplies.

 Health resources being wasted due to equip-

ment not being repaired.

 Equipment related accidents and risks to staff

and others particularly when electrical equip-

ment is not connected or earthed correctly,

inspected regularly, and serviced.

 Poor laboratory services to patients and relation-

ships between laboratory and medical staff

deteriorating as tests cannot be performed or

test results are delayed due to equipment break-

downs.

 Laboratory staff becoming dissatisﬁed at not

being able to do their job.

To avoid such equipment related problems, the

management of equipment must include:

– guidelines covering equipment speciﬁcations,

standards, and purchasing.

– inventory of all the equipment in the laboratory,

giving manufacturer, model details, date of pur-

chase and order number, price paid, supplier,

power requirements, source of replacement parts

with code numbers, checks and maintenance

schedules.

– preparation of written standard operating pro-

cedures (SOPs) covering the use and mainten-

ance of each item of equipment with safety

considerations.

– training of laboratory staff in the use, control, and

care of equipment and provision of continuing

on-site support.

– procedure for reporting equipment faults and

ensuring faulty equipment is not used, and pro-

cedure for the rapid repair of equipment.

Note: Guidelines for the selection and purchasing of

equipment and how to keep equipment in working

order can be found in subunit 4.1. Equipment safety

is described in subunit 3.6.

Managing laboratory supplies

Before any district laboratory is established, a reliable

system for supplying it must be identiﬁed and orga-

nized. As mentioned in subunit 2.3, district labora-

tory costs must be budgeted separately from those

of pharmacy with a separate fund allocated and

16 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

2.1

available for the purchase of laboratory items.

A policy covering the regular supply of reagents

and other items to district laboratories and a system

for monitoring stocks are essential if laboratory

services are to be available and free from disruption

and staff are to remain motivated and not frustrated

in their work.

Every district laboratory, with the help of the

district laboratory coordinator, should prepare an

Essential Laboratory Reagents and Supplies List for

the items it needs on a regular basis. It is important

to purchase chemicals, reagents, test kits, and other

supplies from known reliable professional sources to

avoid receiving substandard goods, e.g. test kits

which have false expiry dates, or manipulated

potencies.

The quality of supplies must be checked

by a trained laboratory worker.

An efﬁcient system is needed to supply outreach

laboratories with standardized reliable reagents and

other laboratory items. District laboratory staff must

keepaccurate signedre cordsof allitems requisitioned

andreceived. Supplies mustb erequested correctly. A

careful inventoryshould be kept of all supplies and a

workable systemfor controlling stock levels.

A reliable system must also be established for

packing and transporting laboratory supplies, includ-

ing heat-sensitive reagents, to outreach laboratories.

It is often possible to use the same system which

exists for the transport of essential drugs to health

centres.

STAFFINGOF DISTRICTLABORATORIES AND

COMPETENCE OF STAFF

The quality of district laboratory practice is directly

dependent on the quality of performance of district

laboratorypersonnel. Thosein chargeof district health

care andlaboratory services are responsible for:

 Deciding the grades, salary structure, and num-

ber of laboratory personnel required to staff the

service and the career development of staff.

 Preparing job descriptions for each grade of

district laboratory worker and the qualiﬁcations

each grade requires.

 Ensuring all laboratory personnel are well trained

(see subunit 1.3) and supported in their work-

place.

 Employing as district laboratory workers only

those who are:

– qualiﬁe d and competent,

– intereste d in district health care,

– speak the loc al language and are likely to be

accepted by the community.

Before being employed, a laboratory ofﬁcer must

have:

– visite d the laboratory in which he or she will

work,

– studie d the job description and discussed

terms of employment,

– produce d a valid Certiﬁcate of Qualiﬁcation

(to be checked by the employer).

If previously employed, references should be

obtained.

Contract of employment

Employers should provide all laboratory personnel with a

written contract of employment, detailing grade of

worker, responsibilities, salary and method of payment,

hours of work, emergency working arrangements, vaca-

tion, and any other relevant issues.

Note: For all newly appointed district laboratory

staff, there should be a probationary working

period of three months.

 Ensuring the working conditions of district lab-

oratory staff are safe and acceptable and staff are

paid according to their contract of employment.

 Supervizing adequately the work of newly

appointed staff. The district laboratory coordi-

nator has a responsibility to visit all laboratories in

the district on a regular basis to discuss the work,

motivate staff, address any problems, check the

quality of reports and records, and assess work-

ing practices and performance standards.

Important: Where trainees perform laboratory

tests, their work must be supervized. No test re-

sult should be issued before it has been veriﬁed

by a qualiﬁed laboratory ofﬁcer.

 Providing support in the workplace and continu-

ing education for all district laboratory personnel

as discussed in subunit 1.3.

QUALITY ASSURANCE TO OBTAIN CORRECT TEST

RESULTS

Immediate and long term clinical, public health, and

health planning decisions are based on the results of

laboratory tests. Incorrect, delayed, or misinterpreted

test results can have serious consequences for

patients and communities, undermine conﬁdence in

the service, and waste scarce district health

resources.

Achieving reliability of test results is dependent on:

 Understanding what are the commonest causes

of inaccuracy and imprecision in the perform-

ance of tests and of delayed or misinterpreted

TOTALQUALITY MANAGEMENT OF DISTRICT LAB ORATORY SERVICES 17

2.1

test results (see subunit 2.4, Quality assurance

and sources of error).

 Taking the necessary steps to prevent and mini-

mize errors by:

– implementing Standard Operating Pro-

cedures (SOPs) with quality control for all

district laboratory activities.

– introducing every month a quality control

day and an external quality assessment

scheme for outreach laboratories (see later

text, Role of the district medical ofﬁcer in

TQM).

– appointing a district lab oratory coordinator

to monitor the performance of district lab-

oratories (see later text).

 Agreeing with those requesting laboratory tests,

policies of work that will enable the laboratory to

provide an efﬁcient, safe, cost-effective, and

reliable service (see subunit 2.4).

 Maintaining good communications between lab-

oratory staff and those requesting tests.

Note: A deﬁnition of quality assurance (QA) and

how it is applied in district laboratory practice can be

found on pages 31–34. Guidelines on the QA of

parasitological tests are described on pages

178–182, clinical chemistry tests on pages 313–333,

microbiology on pages 3–6 in Part 2, haematology

tests on pages 267–270 in Part 2, and blood

transfusion techniques on pages 350–351 in Part 2.

RESPONSIBILITYFOR TQM

In tropical and developing countries few district hos-

pitals have a resident or visiting pathologist or even

a medical ofﬁcer with sufﬁcient knowledge of lab-

oratory practice to assist in the running of district

laboratories. In the past this has lead to neglect of

district laboratories and poor performance by staff.

With the development of district health care sys-

tems, most district laboratory services are now man-

aged locally by a district laboratory coordinator

helped by a district hospital medical ofﬁcer trained in

the use of laboratory investigations and basic quality

assurance.

Responsibilities of the district laboratory

coordinator

The person appointed as a district laboratory coordi-

nator must be a senior well trained medical labora-

tory ofﬁcer with management skills and several years

experience of district laboratory practice and training

of laboratory personnel. Opportunities must be pro-

vided for continued professional development and

the learning of management skills.

The most important responsibilities of the district

laboratory coordinator are to:

 Assist in the establishment, integration, and

management of district laboratories.

 Visit district laboratories at least every three

months to help and motivate staff, monitor the

quality of laboratory service being provided,

discuss problems, and inform staff of important

district health activities.

 Help to prepare, apply, and update standard

operating procedures (SOPs) for district labora-

tories.

 Implement and monitor safe working practices

and investigate laboratory accidents.

 Promote effective communication between lab-

oratories, and good working relationships

between laboratory staff, patients, and those

requesting laboratory tests.

 Check whether equipment is functioning well

and whether laboratory workers are using, clean-

ing, controlling/calibrating, and maintaining

equipment correctly.

 Make sure essential reagents and other supplies

are being ordered correctly and reaching labora-

tories satisfactorily.

 Examine quality control data, laboratory reports,

and records.

 Help laboratory staff to learn new skills and work

more efﬁciently.

 Implement an effective quality assurance scheme

to assess the performance of laboratory staff and

promote continuous improvement in the quality

of district laboratory services.

 Investigate complaints from users of the labora-

tory and check whether the waiting time for test

results is acceptable.

 Review the routine, emergency, and ‘on call’

workload of district laboratories.

 Evaluate laboratory operating costs and prepare

the yearly budget.

 Check whether there is any unauthorized use of

district laboratories.

 Make sure specimens are being collected and

transported correctly and the system for referring

specimens from health centres to the hospital

laboratory is working well.

 Ensure district laboratory staff are well trained for

18 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

2.1

their job (see subunit 1.3) and the work of

trainees is being adequately supervized.

 Participate in laboratory clinical meetings and

district health meetings.

 Every three months prepare a laboratory report

for the district health management team, detail-

ing the utilization of district laboratories, tests

requested, workload, laboratory expenditures,

staff needs and training.

Important: Because of the comprehensive duties of

the district laboratory coordinator, it is rec-

ommended that the person appointed to do this job

is carefully selected and is not already fulltime

employed as laboratory ofﬁcer in charge of the dis-

trict hospital laboratory. A check list should be pre-

pared of the activities which need to be performed

during visits to the district’s laboratories and also a

list of the tools, spares, reagents, standards, etc, that

the coordinator should take.

Role of the district hospital medical ofﬁcer in

TQM of district laboratory services

The medical ofﬁcer appointed to help in the running

of district laboratory services must be a good com-

municator and ‘laboratory-friendly’.

The following

are practical ways in which a district hospital medical

ofﬁcer with only a limited knowledge of laboratory

procedures can help to motivate laboratory staff and

contribute to improving the quality of service

provided, particularly that of the district hospital

laboratory:

 Visiting the laboratory on a regular basis to dis-

cuss the workload, any specimen collection prob-

lems, and any difﬁculties which may be affecting

the quality of work or well being of the labora-

tory staff.

 Promoting good communications between the

laboratory and the medical and nursing staff and

monitoring how the results of tests are being

used.

 Monitoring whether test results are being

veriﬁed and clearly reported on request forms,

and whether the target turnaround times for

tests are being met and if not how the situation

can be improved.

 Checking with the senior laboratory ofﬁcer

whether equipment maintenance schedules are

being performed.

 Observing whether essential safety is being prac-

tised, e.g. glassware and plasticware are being

decontaminated before being washed and

reused, specimens are being collected, tested

and disposed of safely, laboratory staff are not

mouth-pipetting specimens and reagents, the

laboratory is being kept clean and tidy, ﬂam-

mable and toxic chemicals are being stored

safely, laboratory staff know what to do if there is

a ﬁre and are trained in essential First Aid.

 Investigating the reasons for any tests not being

performed, particularly if due to supplies not

being ordered or delivered.

 Establishing with the help of the district labora-

tory coordinator, a monthly quality control day.

Quality control day: This can best be achieved by

the medical ofﬁcer dividing a few specimens,

giving each a different identity and checking

whether the results of all the specimens are the

same (within acceptable limits). If not, the medi-

TOTALQUALITY MANAGEMENT OF DISTRICT LAB ORATORY SERVICES 19

2.1

cal ofﬁcer should ask the senior laboratory ofﬁcer

to investigate the likely cause(s), e.g. SOPs not

being followed by the staff, an instrument

malfunctioning, variable pipetting, deteriorating

reagents, staff not having sufﬁcient experience.

To control the reporting of microscopical

preparations, the medical ofﬁcer should obtain

stained quality control smears of specimens from

the district laboratory coordinator, e.g. smears

showing malaria parasites, trypanosomes, AFB,

gram negative diplococci, blood cells, etc. The

medical ofﬁcer should ask as many of the staff as

possible to examine the preparations.

 Holding monthly clinical meetings with labora-

tory staff and the district laboratory coordinator

to discuss interesting test results and the ﬁndings

of the quality control day.

CORRECT USE OF THE

LABORATORY IN

DISTRICT HEALTH CARE

see subunits 2.1 and 2.2

MANAGEMENT OF

EQUIPMENT AND

SUPPLIES

see subunits 2.1 and 4.1

TRAINING AND

ONGOING SUPPORT

OF STAFF IN THE WORK

PLACE

see subunits 2.1 and 1.3

QUALITY ASSURANCE

SOPs, QC, EQA.

GOOD

COMMUNICATIONS

see subunits 2.1, 2.4, 2.7

MANAGEMENT OF

FINANCES AND

BUDGETING

see subunit 2.3

PROVIDING A QUALITY

SERVICE TO USERS OF

THE LABORATORY

see subunit 2.1

Abbreviations: TQM Total Quality Management, QA Quality Assurance, SOPs Standard Operating Procedures, QC Quality

Control, EQAExternal Quality Assessment.

TQM

2.2 Selection of tests and

interpretation of test results

The importance of using laboratory investigations

correctly in district health care has been outlined in

subunit 2.1 (TQM). This subunit covers in more

detail the factors that need to be considered when

selecting tests and interpreting test reports.

20 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

2.1–2.2

REASONS FOR PERFORMING LABORATORY TESTS

The reasons for performing laboratory tests and

follow-up investigations must be clear. The tests

performed in district laboratories must reﬂect the

common and emergency health needs of the area

and provide information that can be easily inter-

preted. The tests must also be efﬁcient, i.e. provide

sufﬁcient beneﬁt to justify their cost and any risks

involved in their performance.

Medical ofﬁcers should encourage qualiﬁed ex-

perienced laboratory staff to provide maximum

information from laboratory tests and to proceed to

further testing when this is obviously indicated and

will lead to better and earlier treatment for a

patient.

Examples of maximizing information from laboratory tests

 When examining a thick stained blood ﬁlm for malaria

parasites, report also if the neutrophils or eosinophils are

signiﬁcantly increased. If no parasites are found check the

preparation for trypanosomes or borreliae if the patient is

from an area where these organisms are found.

Check also for signiﬁcant background reticulocytosis

which may indicate sickle cell disease if the patient

(particularly a child) is from a haemoglobin S (Hb S)

prevalent area. Perform a sickle cell test and examine a

thin stained blood ﬁlm.

 If many malaria parasites are found in the blood of a

young child, measure and monitor the haemoglobin.

 When pus cells are found in the urine from a male patient,

Gram stain the urine sediment and look for Gram nega-

tive intracellular diplococci, indicative of gonorrhoea.

 When ﬁnding glycosuria, measure the fasting blood

glucose.

 If red cells and protein are found in urine from a patient

living in a schistosomiasis endemic area, examine the

urine sediment for S. haematobiumeggs.

 If blood and mucus are present in faeces, examine the

specimen carefully for the eggs of S. mansoni or motile

amoebae with ingested red cells, indicative of amoebic

dysentery.

 If faeces appears like rice water, inoculate it in alkaline

peptone water and look for vibrio.

 If there is a rapid fall in haemoglobin and a rising ESR in

a febrile patient from a trypanosomiasis endemic area,

check the blood for trypanosomes.

 When the blood ﬁlm from an adult shows signiﬁcant

hypochromia and the haemoglobin is low, check the

faeces for hookworm eggs.

In deciding which tests and test methods are appro-

priate it is important to consider:

– the clinical and public health needs of the district,

– wellbeing of patients,

– laboratory technical aspects,

– costs involved.

Continuing improvement in quality

The following are effective ways of monitoring

progress and implementing ongoing improve-

ment in the quality of district laboratory ser-

vices:

● Discussing with the users of district labora-

tories what changes and improvements are

needed and how laboratory tests can be

used more cost-effectively and efﬁciently.

● Regularly reviewing and updating standard

operating procedures and laboratory

policies.

● Improving the system for supplying district

laboratories.

● Monitoring quality control and the effective-

ness of the district quality assessment

scheme.

● Investigating errors at the time they occur,

taking corrective action, and checking

whether the action taken has been effective.

● Considering how to improve specimen

collection and transport in the district and

how to reduce the time patients wait for test

results.

● Providing on-site continuing education and

support for district laboratory staff.

● Ensuring all laboratories in the district

are kept informed of district health pro-

grammes.

● Looking ahead, planning, and budgeting

realistically for future laboratory needs.

● Promoting the right attitude to quality which

has been summarized by Elsenga as ‘willing

people make failing systems work, unwilling

people make working systems fail’.

Clinical and public health considerations

Priority diagnostic tests

Priority should be given to selecting those tests that

help to diagnose those conditions:

– that are difﬁcult to diagnose accurately from clin-

ical symptoms alone, particularly at an early stage

of an illness, when a patient has a secondary

infection or has received drugs or herbal

medication at home before attending the clinic.

– that require lengthy, high risk, or expensive treat-

ment.

– that can cause epidemics with high mortality or

much illhealth and disability.

Tests needed in treatment, disease control and

prevention

Other tests will also be required in the treatment,

control, and prevention of disease to:

– achieve a more rational and selective use of

drugs.

– detect and monitor drug resistance particularly

resistance to antimalarials and antibiotics.

TOTALQUALITY MANAGEMENT OF DISTRICT LAB ORATORY SERVICES 21

2.2

– assess the severity of illness and likely outcome of

an illness.

– make the treatment and care of a patient safer

and help to assess the effectiveness of treatment.

– establish a baseline value for follow-up care.

– assess whether a patient being treated in a health

centre needs to be referred to the district hospi-

tal for specialist care.

– monitor anaemia or occupational disease.

– monitor the health of pregnant women.

– improve the care of HIV infected persons.

– identify disease carriers and improve case-

ﬁnding.

– detect carriers of Hb S as part of family planning

counselling services.

– monitor microbial pollution of community water

supplies.

– prevent blood transmissible infections, particu-

larly those caused by HIV and hepatitis viruses.

– promote community health education.

– increase the validity of disease reporting by

providing reliable information on the causes and

pattern of illhealth in the community.

Important: Clinicians and public health ofﬁcers must

be kept up to date regarding the availability and rel-

evance of new technologies. Laboratory personnel

need to know how tests are used to be able to

report tests informatively.

The sensitivity and speciﬁcity of tests are

explained in subunit 2.2.

Patient considerations

In the selection of tests and test methods the follow-

ing are important patient considerations:

 Many patients requiring laboratory investigations

in tropical and developing countries will be

young children, therefore specimen collection

techniques must be appropriate.

 Specimen collection techniques for all patients

must be safe, respectful of the person, as stress

free as possible, and culturally acceptable.

 When several different tests requiring blood are

required, the tests should be coordinated to

avoid the unnecessary repeated collection of

blood from patients.

 A high proportion of patients will be outpatients

requiring their test results before receiving treat-

ment, therefore rapid techniques are needed.

 Tests performed must lead to improved quality

of patient care and be affordable. Patients should

Relevance of laboratory tests

It is both wasteful and unscientiﬁc to perform

laboratory tests:

● that provide little useful clinical or public

health information,

● that contribute only minimally to patient

management and quality of care,

● that are not sufﬁciently rapid, reliable,

sensitive, or speciﬁc for the purpose.

Tests should be requested rationally and speciﬁ-

cally based on the value of the information they

provide and their cost-effectiveness. Ordering

several tests that provide similar information

cannot be justiﬁed. Asking the following ques-

tions will help medical ofﬁcers to request tests

appropriately:

– why am I requesting this test?

– is it affordable?

– can the laboratory perform it reliably, and

how long will it take to get the result?

– what will I look for in the result?

– how will it affect my diagnosis and my care

of the patient?

– ultimately, what will be the beneﬁts to the

patient and to the community?

always be advized why a particular test is needed

and what is required in providing the speci-

men(s).

 Whenever possible patients should not have to

travel considerable distances for essential labora-

tory investigations, e.g. tests required by preg-

nant women.

Laboratory considerations

The following are important technical considerations

in the selection of tests, test methods, and in decid-

ing which tests should be performed in outreach

laboratories and in the district hospital laboratory:

 Competence and experience of local laboratory

staff and whether support can be provided on a

regular basis.

 How well a test can be standardized and con-

trolled in the laboratory in which it will be

performed.

 Communication and transport links that exist

between outreach laboratories and the hospital

laboratory to facilitate the referral of specimens.

 Reagents, standards, controls, and consum-

mables required to perform tests, including their

cost, complexity of preparation or availability as

ready-made products, stability and storage and

hazards associated with their use particularly in

outreach laboratories.

 Quality and quantity of water required.

 Equipment needed, including its running cost,

power requirements, complexity and safety of

use, maintenance, local repair facilities and avail-

ability of replacement parts, anticipated reliability

and working life.

 Type of specimen required, including its collec-

tion, stability, transport, storage, safe handling

and disposal.

 Performance time of tests and how frequently

particular tests are requested.

Cost considerations

The following are important ﬁnancial considerations

when selecting tests and test methods:

 How expensive is the test, for example:

– what is the cost of colle cting the specimen

including the cost of the specimen container,

and is there a signiﬁcant cost in preparing

the patient?

– does the test re quire the use of inexpensive

reagents that can be prepared locally or ex-

pensive reagents and controls that have a

22 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

2.2

limited shelf-life and need to be imported?

– does the test re quire the use of equipment

which is expensive to operate and maintain?

– is the te chnique simple and rapid or com-

plex and lengthy, and does it require the

skills of a specialist laboratory ofﬁcer?

Note: Subunit 2.3 describes how to estimate the

unit cost of a test based on laboratory operating

costs, number of tests performed, and the work-

load unit value of the test.

 What are the costs of the different technologies?

Can using an expensive technology be justiﬁed

when there is a reliable cheaper alternative for

obtaining the same or similar information? A

costly newtechnology does not necessarily mean

that itwill have improved performance character-

istics and be more appropriate. It may even have

important limitations, e.g. a rapidmalaria antigen

test that is not able to differentiate species.

 Is it cost effective for district laboratories to use:

– clinic al chemistry kits for frequently per-

formed tests when the reagents and

standards can be easily and cheaply made in

the laboratory?

– a diagnostic kit test in district lab oratories

when the format of the kit is designed for

testing large numbers of specimens at one

time and the working reagents have poor

stability?

– urine reagent strip tests in areas of high rela-

tive humidity when moisture causes the

strips to deteriorate rapidly, resulting in sig-

niﬁcant wastage (and unreliable test results).

 How will the cost of tests be met? It is essential

that tests are ordered only when they are

needed and the cost is known of each test when

performed in a health centre laboratory and in

the district hospital laboratory.

Note: Financing district laboratory services and con-

trolling laboratory costs are discussed in the next

subunit (2.3).

How to decide which tests are the most

important in community-based health care

Answering the following questions will help medical

ofﬁcers and community health workers to decide

which tests are the most important in meeting

individual and community health needs:

1 What are the commonest and most life-

threatening conditions for which people seek

medical care? Make separate lists for infants,

children, men, non-pregnant women, pregnant

women.

2 What conditions are the most difﬁcult to diag-

nose? Which laboratory tests are the most likely

to assist in investigating these? Which conditions

if misdiagnosed could have serious conse-

quences for an individual and public health?

3 For what symptoms are antibiotics being pre-

scribed and how often? Which laboratory tests

could be used to conﬁrm a diagnosis or rule out

an infection before prescribing an antibiotic?

4 What is the transmission pattern of malaria? How

often are antimalarials being prescribed without

conﬁrming the diagnosis microscopically? Is drug

resistance a problem?

Misdiagnosis of malaria

An increasing number of surveys show malaria is often

misdiagnosed both by experienced and less experienced

medical ofﬁcers and community health workers, leading

to costly antimalarial drugs being prescribed unnecessari-

ly, and the true cause of a patients’s illness remaining

undiagnosed. Misdiagnosis also leads to incorrect report-

ing of malaria incidence.

5 How many patients are being treated without

being diagnosed, e.g. patients with fever of un-

known origin, headache, or general body pain?

Go back through several months’ records to

include seasonal inﬂuences.

6 How many patients return to see the medical

ofﬁcer or community health worker because the

prescribed drugs or other treatment appear not

to have worked? Looking back, could any lab-

oratory test if performed at the time of the ﬁrst

visit have helped the patient to receive a more

appropriate treatment and prevent their con-

dition worsening.

7 Are there any prevalent infectious diseases in the

community which the laboratory could investi-

gate to assist in breaking the cycle of transmis-

sion and preventing reinfection?

8 In the last 12 months have there been any

serious epidemics which the laboratory could

have helped to bring more quickly under control

or even helped to prevent?

9 Are there any major health education pro-

grammes which the laboratory could make more

effective, e.g. demonstrating microscopically the

parasites that cause schistosomiasis?

10 How many young children and adults are

needing to travel to the district hospital for lab-

oratory investigations? List the tests being

requested.

Important: It will not be possible in a community-

TOTALQUALITY MANAGEMENT OF DISTRICT LAB ORATORY SERVICES 23

2.2

based laboratory to perform all the tests that are

needed to meet individual and community health

needs. Some of the limiting factors are discussed in

subunit 1.2.

Further information:Important guidelines on the selection of

laboratory tests can be found in a WHO laboratory document:

Laboratory services for primary health care: requirements for

essential clinical laboratory tests (see Recommended

Reading).

LABORATORYREQUEST FORM

The format of laboratory request forms should be

clear and standardized throughout the district. The

layout should be discussed and agreed by labora-

tory staff and users of the laboratory service.

Whenever possible laboratory request forms,

suitable for use in district laboratories should be pre-

pared by a central stationery ofﬁce. Where forms are

not supplied from a central source, simple request

forms can be prepared locally. Standardization and

clarity in presenting and reporting results can be

achieved by the use of rubber stamps (see Fig. 2.1).

Adequate ink, however, must be used and the

stamp must be positioned carefully.

Information to accompany requests for

laboratory tests

The laboratory request form should be dated and

provide the following information:

 Patient’s full name, age, and gender.

 Address or village of patient (valuable epidemio-

logical data).

 Inpatient or outpatient identiﬁcation number.

 Relevant clinical information regarding patient’s

condition.

 Details of drugs or local medicines taken by or

administered to the patient before visiting the

health unit or hospital, and drugs that have been

administered by the health unit or hospital prior

to collecting the specimen, e.g. antimicrobials,

antimalarial drugs.

 Speciﬁc test(s) required.

 Specimen provided.

 Origin of request if from an outreach health

centre or maternity unit.

 Name of the medical ofﬁcer, community health

worker, or midwife requesting the test and to

whom the report should be sent.

Urgent tests: Only those tests should be

requested urgently that are required for the

immediate care of a patient or to manage a serious

public health situation.

Note: The specimen container must be clearly

labelled with the patient’s name, identiﬁcation

number, and the date and time of collection.

Patient conﬁdentiality

As soon as request forms and specimens are

received by the laboratory the staff have a responsi-

bility to ensure the request forms are not read by

unauthorized persons.

Laboratory staff must never disclose any

information they may learn about a patient or a test

result to anyone other than the health personnel

caring for the patient. Respecting patient conﬁden-

tiality must also extend to when laboratory reports

are issued. Reports should be delivered in sealed

envelopes,labelle dCO NFIDENTIAL LABORATORY

REPORTS, or in labelled sealed folders which can be

returned to the laboratory for re-use.

REPORTING AND RECORDING TEST RESU LTS

Laboratory staff should provide as much relevant in-

formation as possible to assist those requesting tests

to interpret the results of tests correctly and use the

information in the best possible way to beneﬁt

patients and the community. Reports should be

clearly and neatly written (particularly ﬁgures).

Standardization in reporting test results

Standardization in the presentation of reports and

use of units is important because it helps in the

interpretation and comparison of results, contributes

to the efﬁciency of a laboratory service, and is of

value when patients are referred from one health

unit or hospital to another. The use of SI units in the

reporting of tests can be found in subunit 2.5.

Laboratory reports in patients’ notes

The system sometimes used in district hospitals of

‘charting’, or transferring, laboratory results from lab-

oratory registers or from laboratory request forms

into patients’ notes is not recommended. Not only is

it time-consuming but it can give rise to serious

errors when results are not copied correctly or in

their entirety. A patient’s notes must contain the

signed reports issued by the laboratory.

When resources are limited, an inexpensive reli-

able way of inserting laboratory reports in patients’

24 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

2.2

notes is to report results on small stamped forms

and attach these to a sheet of paper reserved for

Laboratory Reports in each patient’s notes. If the

pieces of paper are arranged as shown in Fig. 2.1,

several reports can be attached to one sheet.

Keeping laboratory reports in one place in a

patient’s notes has the added advantage that the

latest test result can be quickly compared with a

previous result.

Recording results in the laboratory

In district laboratories, records of test results can be

kept by retaining carbon copies of reports, using

work sheets, or recording test results in registers (ex-

ercise books). Whichever system is used it must be

reliable and enable patients’ results to be found

quickly. Test records are also required when prepar-

ing work reports and estimating the workload of the

laboratory.

If carbon copies or work sheets are used these

must be dated and ﬁled systematically each day. If

registers are used, backing cards which are headed

and ruled can be placed behind pages to avoid

having to rule and head each page separately. The

cards must be heavily ruled with a marker pen so

that the lines can be seen clearly. Separate registers,

each with its own cards, can be prepared to record

the results of haematological, microbiological, clinical

chemistry, urine and faecal tests. Examples of cards

which could be used in a Urine Analysis Register are

shown in Fig. 2.2.

In smaller district laboratories the registers can

also be used to record daily quality control infor-

mation, e.g. reading of a haemoglobin control. Daily

checks on the performance of equipment, e.g. tem-

perature readings should be recorded in a quality

control (QC) book or on separate sheets as part of

equipment control procedures.

INTERPRETATION OF TEST REPORTS

In the use and interpretation of laboratory test re-

sults it is important to understand the limitations of

tests, e.g. the ability of tests to indicate when disease

is present or absent or whether the value in a report

is normal or abnormal for a patient. Reference

ranges are required for the interpretation of quanti-

tative test results.

The performance characteristics of tests are also

important, e.g. how accurately and precisely (repro-

ducibly) a test can be performed (see subunit 2.4)

and for some tests, reader variability can also be

important (see later text).

Ability of diagnostic tests to indicate presence

or absence of disease

The ability of a diagnostic test to indicate when a

disease is present or absent is dependant on its

quality and is described in terms of:

– sensitivity,

– speciﬁcity,

– predictive value.

Sensitivity (true positive rate)

This is the frequency of positive test results in

patients with a particular disease, e.g. 95% sensitivity

implies 5% false negatives. A test which has 100%

sensitivity is always abnormal (or positive) in patients

with the disease.

TOTALQUALITY MANAGEMENT OF DISTRICT LAB ORATORY SERVICES 25

2.2

Calculating sensitivity

Sensitivity 

Screening tests should be sensitive to ensure

that where possible, a positive test result is obtained

in all patients with the disease. The higher the sen-

sitivity of a test, the less likely it is to fail to diagnose

a person as having the disease, i.e. the fewer

the number of false negative results. For example,

it is important to use a high sensitivity HIV serolog-

ical test when screening blood supplies for HIV

antibody.

Analytical sensitivity: this is different to statistical sensitivity

as described above. Analytical sensitivity relates to the lowest

result which can be reliably differentiated from zero.

total number positive results



total number infected patients

Fig. 2.1 Transfering laboratory results into the hospital notes of a patient.

a) Sheet in patient’s notes on to which laboratory report forms are gummed or stapled.

b) Close-up of a simple laboratory form. A rubber stamp can be used to print the upper part of the form.

Fig. 2.2 Example of an exercise book with card inserts to record test results. The lines from the ruled cards show through the

pages of the book

Speciﬁcity (false positive rate)

This is the frequency of negative test results in

patients without that disease. A 95% speciﬁcity

implies 5% false positives.

Calculating speciﬁcity

Speciﬁcity 

Deﬁnitive tests should be speciﬁc to ensure a

patient is not incorrectly diagnosed as having the

disease, i.e. false positive result. The higher the speci-

ﬁcity of a test, the less likely it is to diagnose a

person who does not have the disease as having it,

i.e. the fewer the number of false positive results.

Examples of tests with high speciﬁcity include the

Ziehl-Neelsen technique for AFB, and microscopical

parasitological diagnostic techniques where parasitic

forms can be identiﬁed. Sensitivity, however, can

vary greatly particularly when pathogens are ex-

creted intermittently or in variable numbers or when

only a small amount of specimen is examined.

Neither speciﬁcity nor sensitivity is dependent on

the prevalence of disease for which the test is being

performed.

Analytical speciﬁcity: this is different to statistical speciﬁcity

as described above. Analytical speciﬁcity depends on whether

only the substance under investigation is measured.

Predictive value of a positive test result

This is the percentage of positive results that are true

positives when a test is performed on a deﬁned

population containing both healthy and diseased

persons. It depends not only on the speciﬁcity and

sensitivity of the test but particularly on the preva-

lence of the disease in the population tested as can

be shown in the following examples:

Predictive % value of positive test result 

 100

Examples

Low prevalence and predictive value of a positive test.

For example, if a test has 90% sensitivity, 95% speciﬁcity (5%

false positives), and the condition it detects has a 2% preva-

lencein the population it follows that:

 2% prevalence means, of 1000 persons, 20 have the

disease in the population.

 18 will be detected (true positives), i.e. 90% of 20 based

on 90% sensitivity.

 49 will have false positive tests, i.e. 5% of 980 based on

95% speciﬁcity.

 there will be a total 67 positive tests (18 true, 49 false).

 Predictive value of positive test:

100  27%

18 (true positives)



67 (all positive tests)

True positives



True positives False positives

total number negative results



total number uninfected patients

26 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

2.2

The predictive value of a positive test is therefore low when

the prevalence is low.

High prevalence and predictive value of a positive test

For example, if the test has 90% sensitivity, 95% speciﬁcity

and the condition it detects has a 20% prevalence in the

population it follows that:

 20% prevalence means of 1000 persons, 200 have the

disease in the population.

 180 will be true positives, i.e. 90% of 200.

 40 will have false positive tests, i.e. 5% of 800.

 there will be a total of 220 positive tests (180 true, 40

false)

 Predictive value of positive test:

100  82%.

The predictive value of a positive test is therefore high when

the prevalence is high.

Predictive values are important diagnostically as they

give the probability that an abnormal result comes

from someone with disease. The higher the predic-

tive value of a test, the higher the possibility in any

population that a positive test means disease.

If a disease has a low prevalence in the popu-

lation being tested, there will be a higher number of

false positive results due to the higher proportion of

persons without the disease and therefore a positive

result has a lower predictive value.

The positive predictive value of a test for a

disease will increase both with the sensitivity of the

test and the prevalence of the disease. To be useful,

a test’s predictive value must be greater than the

prevalence of the disease.

Even when a test is highly sensitive and speciﬁc

there is still a possibility of false positive results when

the prevalence of the disease is low. Conﬁrmatory

testing becomes important in these situations.

Reader variability

The reader variability percentage gives an indication

of how easy it is to report a visually read test. The

clearer a test result is to read the lower will be the

reader variability. Difﬁcult to read test results will

result in greater reader variation.

Reader variability is one of the operational

characteristics used by WHO to evaluate HIV test

kits when the readings are performed without

equipment. The reader variability is expressed by

WHO as the percentage of sera for which test results

are differently interpreted by different readers. To

reduce reader variability, most manufacturers of

serological tests include weak positive controls and

artwork showing a range of positive test results.

Some manufacturers make available instruments to

reduce the variability inherent in reading test results

visually.

180 (true positives)



220 (all positive tests)

In reporting microscopical preparations, reader

variability can be reduced by using reference prep-

arations to assist in the identiﬁcation of organisms

and cells, preparing specimens correctly, and exam-

ining preparations for the correct length of time.

Recognizing that some specimens and preparations

will always be more difﬁcult to report, reader vari-

ability can be minimized by following standardized

procedures, using adequate controls and reference

materials, and by improving the quality of training

and supervision when introducing new tests.

REFERENCE RAN GES FOR QUANTITATIVETESTS

Laboratory staff and those requesting tests should

know the accepted reference ranges and clinical

signiﬁcance of the results of the quantitative tests

performed in the laboratory. This will ensure that

signiﬁcantly abnormal results are detected, checked,

reported, and acted on as soon as possible. Prompt

action by laboratory staff may prevent loss of life or

lead to an earlier treatment with more rapid recov-

ery for a patient.

Clinical signiﬁcance of abnormal test results

The clinical signiﬁcance of abnormal results for the quantita-

tive tests included in this publication can be found at the end

of each test method.

Test results are affected both by biological and lab-

oratory analytical factors and these need to be

considered when deciding the reference range for

each test.

Biological factors

The following are among the biological factors that

contribute to differences in test results among

healthy people:

 Age: e.g. higher plasma urea concentrations are

found in the elderly. Alkaline phosphatase activity

is higher in growing children compared with

adults. Reference values from neonates are very

different from those of adults.

 Gender: e.g. higher values of haemoglobin,

plasma creatinine, urate, and urea are found in

men compared with women during the repro-

ductive phase of life.

 Diet and nutritional state: e.g. plasma cholesterol

and calcium are affected by diet.

 Time of the day (diurnal variation): e.g. serum

iron levels rise as the day progresses.

 Posture: e.g. plasma protein levels are lower in

samples collected from patients when they are

TOTALQUALITY MANAGEMENT OF DISTRICT LAB ORATORY SERVICES 27

2.2

lying down.

 Muscular activity: e.g. the concentration of

plasma creatinine rises following exercise.

 Dehydration: e.g. haemoglobin, PCV, white

blood cells increase due to decrease in plasma

volume.

Reference ranges are also affected by weight, phase

of menstrual cycle, emotional state, geographical

location, rural or city life, climate, genetic factors,

cultural habits, smoking, and homeostatic variation.

Some reference values are also altered during

pregnancy, e.g. haemoglobin and PCV values

decrease and neutrophil numbers increase.

Analytical factors

Among the analytical factors that inﬂuence reference

ranges the most signiﬁcant are:

 Type of sample:e.g. the concentration of glucose

is 12–13% higher in plasma than in whole blood.

Small variations also occur between serum and

plasma samples for potassium and some other

substances.

 Test method: e.g. a glucose oxidase enzyme

method will give a narrower reference range for

blood glucose than a Folin-Wu technique be-

cause the enzyme method is speciﬁc for glucose.

 Performance: Some tests can be performed with

less variation than others. The reference ranges

for such tests will therefore be narrower.

How reference ranges are established

The reference range for a particular substance is

worked out by testing and plotting a graph of fre-

quency of value against concentration. For some

assays the graph produced is symmetrical in shape

Fig. 2.3 Symmetrical distribution (Gaussian) graph

showing the highest number of people having

values around the mean (average) with a gradual

decrease in frequency on each side of the mean as

shown in Fig. 2.3.

In statistical terms the distribution of values

around the mean can be expressed as standard

deviation (SD). When the results of a particular test

show a symmetrical (Gaussian) type curve, the refer-

ence range for the substance being measured is de-

ﬁned by a plus or minus 2 SD from the mean (see

Fig. 2.4). This covers 95% of the ‘healthy’ population

(1 SD covers 68% of the population, and 3 SD

covers 99.7% of the population).

28 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

2.2–2.3

There can be no clear dividing line between

‘normal’ and ‘abnormal’ values. This is one of the

reasons why the term reference range is preferred to

normal range. To interpret test results adequately,

not only should the reference values provided by the

laboratory be considered by clinicians, but also the

levels of abnormality which are likely to be present

in different diseases and in the early and late stages

of a disease.

Action to take when results are seriously

abnormal

As part of standard operating procedures and QA,

laboratories need to decide what procedure should

be followed when a result is seriously abnormal or

unexpected, e.g. when compared with a previous

recent result. For some tests it may be appropriate to

deﬁne a level of abnormality which leads to

immediate action being taken by laboratory staff to

check the result and inform the person treating the

patient.

Important: Whenever a result is communicated

orally, the written report should be issued as soon as

possible. Before being issued, all reports must be

checked (veriﬁed) by the most experienced member

of the laboratory staff. Veriﬁcation of reports is par-

ticularly important when trainees are performing

tests.

2.3 Financing district

laboratory services and

controlling costs

In most developing countries, district laboratory ser-

vices are ﬁnanced centrally by the ministry of health

or at district level through district health councils.

In some countries, laboratory and pharmacy services

share a common budget. Such a policy, however, is

not satisfactory because it frequently leads to under-

resourcing of laboratory services as priority is given

to purchasing drugs. It is therefore recommended

that laboratory services be budgeted and funded

separately. To manage laboratory ﬁnances efﬁciently,

accurate records must be kept of laboratory expen-

ditures and the workload of the laboratory.

Cost recovery schemes

Increasingly district health expenditures are being

met in part by patients contributing towards their

Assessing reference (normal) ranges

Because reference ranges are affected by a variety

of biological and analytical factors, they should be

regarded only as approximate interim reference

ranges to be assessed by clinicians and laboratory

staff at a later stage when sufﬁcient data becomes

available. The central laboratory should assist in

conﬁrming reference values for the population.

Note: The reference ranges given in this publication

have been compiled from accepted western values

and those received by the author from a small num-

ber of tropical countries.

Interpretation of results outside the reference

range

If a patient’s result is outside of the accepted refer-

ence range this does not necessarily indicate ill

health. The patient may be in the 5% minority

healthy group outside the Mean 2 SD range.

Fig. 2.4 Example of Gaussian distribution of plasma total

protein giving a reference range of 60–80 g/l.

health care costs. A partial cost-recovery scheme

provides a revolving fund for the purchase of essen-

tial supplies.

Local fees for laboratory tests should not be

more than can be afforded by patients. Applying an

affordable ﬂat standard rate for the laboratory ser-

vice will help all patients to be tested according to

their health need. Most patients recognize that

reliable locally accessible laboratory testing improves

the quality of their care and often avoids a repeat

visit to the health care centre or a longer more

expensive journey to the district hospital laboratory.

TOTALQUALITY MANAGEMENT OF DISTRICT LAB ORATORY SERVICES 29

2.3

 Cost of services including electricity, gas,

kerosene, water supply, water ﬁltration units and

communication equipment.

 Cost of inspecting, maintaining, and repairing

equipment and equipment depreciation.

 Cost of replacing worn or broken items such as:

– counting chamb ers

– pipettes and general glassware and plastic-

ware,

– cleaning utensils,

– lab oratory linen.

 Cost of specimen containers, swabs, cotton wool,

and dressings.

 Cost of stationery including:

– re cord books,

– lab oratory request forms,

– lab els,

– pens and markers.

 Travel and transport costs including the visits of

the district laboratory coordinator.

 Expenditure involved in cleaning and maintain-

ing the laboratory, and keeping it secure.

Variable and ﬁxed costs

The cost of supplies including reagents and consummables are

usually referred to as variable costs while salaries, equipment

maintenance and depreciation, supervision, and overhead

costs are referred to as ﬁxed costs. Careful records of expen-

ditures must be kept.

Financing health centre laboratories

The operating costs of health centre laboratories

tend to be low because many of the tests are inex-

pensive. If, however, the health centre is not well

attended the cost of maintaining an underutilized

laboratory may be unacceptably high. In an under-

utilized situation it may be more cost-effective to

operate the laboratory on a part-time basis and train

a member of the nursing staff to perform the

required tests and manage the laboratory. It may

also be more cost-effective to send specimens for

non-urgent tests to the district hospital laboratory

when there are reliable facilities for transporting the

specimens and rapid return of test results.

Note: The cost factors that need to be considered

when selecting tests and test methods have been

discussed in the previous subunit (2.2).

Estimating costs of tests

A method of estimating the cost of tests in district

laboratories where the cost of reagents and other

supplies tends to be low can be found in the paper

of Houang.

Individual tests are costed as follows:

STIMATINGLABORATORY OPERATINGCOSTS

The following need to be included when estimating

the yearly variable and ﬁxed costs of operating a

district laboratory:

 Salaries of technical and auxiliary staff.

 Cost of consummables including:

– chemicals, control materials, calibrants,

stains,

– culture me dia and serological reagents,

– ready-made reagents, diagnostic test kits,

reagent strip tests,

– blood colle ction sets, collection bags, blood

grouping antisera and crossmatching

reagents,

– ﬁlter paper and pH indic ator papers,

– coverglasses, microscope slides, pipettor tips,

– disinfe ctants, detergents, soap.

Resourcing of district laboratory practice

Careful analysis and budgeting of laboratory

costs and adequate government resourcing of

district laboratory practice are essential to main-

tain quality of service.

Budgets are more likely to be met when district

laboratory services:

● contribute effectively to improving the

health status of the community.

● can demonstrate reliability, efﬁciency, and

commitment to continuing improvement in

quality.

● provide correct and useful data on

infectious diseases.

● respond rapidly and responsibly when

epidemics occur.

1 Estimate the total cost of operating the laboratory

over a 1 year period (see previous text).

2 List the tests performed and total the number of

each test performed over the year.

3 Estimate the total workload units for each test

performed by multiplying the number of each

test performed by its laboratory workload unit

(LWU). Table 2.2 lists the LWU values frequently

assigned to laboratory tests performed in district

laboratories and the deﬁnition of LWU.

Example: If 523 WBCs are performed in 1 year,

the total LWU for WBCs is 523  6  3138

(where LWU for WBC is 6).

4 Add up the total LWU for each test to give the

yearly total workload for all the tests performed.

5 Divide the total laboratory operating cost by the

total workload to give the total unit cost.

Example: If the total operating cost is US$ 3131

and the total workload is 20913, the total unit

cost is 3131 20 913 US$ 0.15.

6 To obtain the individual cost of each test, multi-

ply the total unit cost by the unit value for each

test.

Examples: If total unit cost is US$ 0.15, a WBC

test would cost 0.15  6  US$ 0.90, a differen-

tial WBC would cost 0.15 11  U S$1.65, etc.

30 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

2.3

CONTROLLING LABORATORYCOSTS

The following can help to control laboratory costs

and minimize waste of laboratory resources:

 If users of the laboratory select tests appropriately

as explained in subunit 2.2.

 Advize medical staff and community health

workers which tests are more complex to per-

form and use expensive reagents or equipment

that is expensive to operate or maintain. Monitor

the use of expensive tests.

 Standardize the technologies and equipment

used in district laboratories.

 Purchase new equipment only after considering

whether it is appropriate (see subunit 4.1), and

whether maintenance costs can be afforded and

justiﬁed.

 Train laboratory staff to work competently and

economically and use equipment correctly (see

subunit 1.3). Staff should know the costs of

reagents, controls, equipment, and replacement

parts.

 Where appropriate, use reusable plasticware in-

stead of glassware. Good laboratory practice can

also help to reduce glassware breakages and

waste from spillages.

 Before purchasing diagnostic test kits, check the

speciﬁcations, storage requirements, and shelf-

life of the stock and working reagents to make

sure the kits can be used cost-effectively.

 Whenever possible use micro-techniques, par-

ticularly for clinical chemistry assays, to reduce

the volume of reagents, calibrants, and controls

needed. Make sure, however, that the total

volume of sample is sufﬁcient for reading the

absorbance.

 Whenever possible, batch test specimens, par-

Table 2.2 Laboratory workload unit (LWU)

values of tests commonly performed in district

laboratories

TEST LWU

Haemoglobin 5

WBC (white cell count) 6

Differential WBC 11

ESR (erythrocyte sedimentation rate) 5

PCV (packed cell volume) 3

Blood grouping: ABO 7

ABO and D 9

Basic urine chemistry (reagent strips tests) 3

Measurement of urine protein 8

Measurement of blood glucose 8

Measurement of blood urea 8

Pregnancy test (rapid test) 2

Rapid plasma reagin (RPR) 2

Ziehl Neelsen 12

Gram 8

Wet faecal preparation 10

Malaria thick ﬁlm 10

Microscopial examinations for other blood

parasites 10

Deﬁnition: The laboratory workload unit (LWU) is a

standardized unit equal to 1 minute of technical,

clerical and aide time. The LWU values in this table

may require amending depending on the method

used to perform tests in different laboratories. The

LWU is not the same as how long it takes to perform

a particular test, e.g. ESR is assigned a LWU of 5 not

1 hour.

Note: Further information on how to estimate the

cost of running a district laboratory service can be

found in the paper of Mundy et al.

ticularly clinical chemistry assays, to economize

on the use of controls and calibrants and

maximize the use of working reagents. This

applies more to district hospital laboratory

practice.

 Make basic easy-to-prepare reagents in the lab-

oratory instead of buying expensive ready-made

products.

 Store chemicals and reagents correctly and take

care to avoid contaminating them.

 Collect specimens and perform tests correctly to

avoid repeating a test unnecessarily. Supervize

adequately the work of trainees and new mem-

bers of staff.

 Every three months review critically the emer-

gency and routine workload of the laboratory.

 Review whether the layout of the laboratory

contributes to an efﬁcient way of working.

 Ensure laboratory buildings, particularly doors,

windows, and vents are secure and every

measure is taken to discourage break-ins and

theft of laboratory equipment and supplies.

 Take precautions to avoid the unauthorized use

of laboratory property.

 Keep accurate records of laboratory expendi-

tures.

PRIVATEDISTRICT LABORATORYPRACTICE

In some developing countries, severe government

under-resourcing for national laboratory services has

led to the growth of private laboratory practice.

Private laboratories may be able to perform tests that

are either temporarily or permanently unavailable at

the district hospital laboratory. For many in the com-

munity, however, the fees charged by the privately

run laboratories are unaffordable.

Where private laboratory practice is used to com-

pliment community district laboratory services,

health authorities have a responsibility to ensure

private laboratories:

– are staffed by qualiﬁed registered laboratory

personnel with a medical ofﬁcer in attendance,

– do not permit laboratory staff to prescribe

drugs,

– have appropriate facilities for the tests being

performed,

– operate safely,

– follow standard operating procedures with

adequate quality assurance,

TOTALQUALITY MANAGEMENT OF DISTRICT LAB ORATORY SERVICES 31

2.3–2.4

– display fees and make these known to patients

before performing investigations,

– keep accurate accounts of income and expendi-

tures.

Most private laboratories do not perform essential

public health laboratory activities or disease

surveillance.

2.4 Quality assurance and

sources of error in district

laboratory practice

The necessity for total quality management in district

laboratory practice has been discussed in subunit 2.1

This subunit covers in detail how to ensure the qual-

ity of test results, i.e. quality assurance. The purpose

of quality assurance (QA) in laboratory practice is to

provide test results that are:

– relevant

– reliable and reproducible

– timely

– interpreted correctly.

QA includes all those activities both in and outside

the laboratory, performance standards, good labora-

tory practice, and management skills that are

required to achieve and maintain a quality service

and provide for continuing improvement.

Deﬁning quality assurance (QA)

QA has been deﬁned by WHO as the total

process whereby the quality of laboratory

reports can be guaranteed. It has been

summarized as the:

● right result, at the

● right time, on the

● right specimen, from the

● right patient, with result interpretation based

● correct reference data, and at the

● right price.

Quality control (QC)

The term quality control covers that part of

quality assurance which primarily concerns the

control of errors in the performance of tests and

veriﬁcation of test results. QC must be practical,

achievable, and affordable.

Effective QA detects errors at an early stage

before they lead to incorrect test results. Laboratory

personnel need to be aware of the errors that can

occur when collecting specimens (pre-analytical

stage), testing specimens (analytical stage), reporting

and interpreting test results (post-analytical stage).

QA is an essential requirement of district laboratory

practice. Implementing QA requires:

 Preparation and use of Standard Operating

Procedures (SOPs) with details of QC for all lab-

oratory tests and activities (see later text).

 System for monitoring whether test results are

reaching those treating patients at an early

enough stage to inﬂuence clinical and public

health decision making.

 Policies of work, i.e. decisions that are taken in

consultation with medical and nursing staff to

enable a laboratory to operate reliably, effec-

tively, and in harmony with the other depart-

ments of a hospital or units of a health centre.

Such policies should cover:

– lab oratory hours and arrangements for

emergency testing of specimens outside of

normal working hours.

– range and cost of tests to b e performed.

– tests which c an be referred to a specialist

laboratory.

– arrangements for the colle ction and trans-

port of routine and urgent specimens, and

their delivery, to the laboratory.

– lab elling of specimens.

– lab oratory request form and patient infor-

mation required.

– time it t akes to perform tests, i.e. target turn-

around times.

– reporting of routine and urgent tests and

delivery of reports.

– re cording and storing of laboratory data.

– health and s afety regulations.

STANDARDOPERATING PROCEDURES (SOPS)

SOPs, sometimes referred to as the local laboratory

bench manual, are required for the following

reasons:

 To improve and maintain the quality of labora-

tory service to patients and identify problems

32 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

2.4

associated with poor work performance.

 To provide laboratory staff with written instruc-

tions on how to perform tests consistently to an

acceptable standard in their laboratory.

 To prevent changes in the performance of tests

which may occur when new members of staff

are appointed. SOPs also help to avoid short-cuts

being taken when performing tests.

 To make clinical and epidemiological interpret-

ations of test results easier by standardizing

specimen collecting techniques, test methods,

and test reporting.

 To provide written standardized techniques for

use in the training of laboratory personnel and

for potential publication in scientiﬁc journals.

 To facilitate the preparation of a list and inventory

of essential reagents, chemicals and equipment.

 To promote safe laboratory practice.

Important features of SOPS

SOPs must be:

● Applicable and achievable in the

laboratory in which they will be used.

● Clearly written and easy to understand and

follow.

● Kept up to date using appropriate valid

technologies.

Preparing SOPs

SOPs must be written and implemented by a quali-

ﬁed experienced laboratory ofﬁcer, and followed

exactly by all members of staff.

For each SOP it is best to follow a similar format with

the information presented under separate headings.

Each SOP must be given a title and identiﬁcation

number, and be dated and signed by an authorized

person.

A list of staff able to perform the test (unsupervized

and supervized) should be identiﬁed in the SOP.

There should also be an indication of the cost of the

test.

The following is a suggested layout for district

laboratory SOPs and appendices to be included in

the SOP Manual.

What to write under headings

VALUE OF TEST

State the main reason(s) for performing the test, i.e.

clinical and/or public health reasons (consult with

medical ofﬁcer(s).

Example: To detect, identify, and quantify malaria

parasites in a person with suspected malaria?

(malaria test).

Indicate any relevant limitations of the test.

PRINCIPLE OF TEST

State brieﬂy the technology used.

Examples: ‘Microscopical examination of Fields

stained thick blood ﬁlm for malaria parasites (malaria

test) ...... or ...... chemical reagent strip test to detect

TOTALQUALITY MANAGEMENT OF DISTRICT LAB ORATORY SERVICES 33

2.4

glucose in urine based on glucose oxidase reaction

(urine glucose test).

SPECIMEN

State the specimen required and how to collect it,

including:

– volume required,

– container and its preparation,

– use of any anticoagulant or stabilizer/

preservative,

– collection procedure (for adult and child) with

health and safety notes,

– how container should b e labelled,

– stability of spe cimen and requirements for

storage and transport,

– time within which the specimen should reach the

laboratory.

Describe the checks to be made when specimen

and request form reach the laboratory and criteria

which may make it necessary to reject the specimen.

State if the specimen requires priority attention (e.g.

c.s.f).

EQUIPMENT

List the items of equipment needed to perform the

test. Main items of equipment such as a microscope,

centrifuge, colorimeter, incubator, water bath/heat

block, etc should be listed in a separate appendix

(e.g. Appendix B) at the back of the SOP Manual

and given a number which can be referenced in

each SOP (e.g. B/1, B/2 etc). The information to be

included in this appendix is described under

Appendix B (see later text).

REAGENTS/STAINS

List reagents, stains, reagent strips, etc needed to

perform the test. Include the reagents and stains in

a separate appendix at the back of the SOP Manual

e.g. Appendix A and give each a number which can

be referenced in the SOP (A/1, A/2, etc). The infor-

mation which needs to be included in this appendix

is described under Appendix A (see later text).

CONTROLS

List controls and source(s) to be used in the test, e.g.

positive and negative controls in serological tests,

control sera in clinical chemistry assays, positive and

negative controls in urine chemical tests, etc.

METHOD OF TEST

Describe in a numbered sequence how to perform

the test. For quantitative tests include details of cali-

bration, use of graph or factor, and calculations.

Describe how to control the procedure and also the

health and safety measures which apply. Full details

TITLE OF SOP

Authorized signature Number:

Date:

Staff able to perform test

● Unsupervized: List names

● Under supervision: List names

Cost of test

Example: Group 1 (high range), Group 2 (medium

range), Group 3 (low range)

Suggested headings(see later text for explanation)

VALUE OF TEST

PRINCIPLE OF TEST

SPECIMEN

EQUIPMENT

REAGENTS / STAINS

CONTROLS

METHOD OF TEST

REPORTING RESULTS / INTERPRETATION

SAFETY MEASURES

SOURCES OF ERROR

REFERENCES

Suggested appendices

The SOP Manual should include the following

appendices (see later text):

APPENDIX A, EQUIPMENT (Items: A/1, A/2, etc)

APPENDIX B, REAGENTS / STAINS (Items: B/1,

B/2, etc)

APPENDIX C, SAFETY (Information: C/1, C/2, etc)

ADDITIONAL NOTES

of safety procedures should be included in a separ-

ate Health and Safety appendix, e.g. Appendix C

with each procedure being given a number, (C/1,

C/2, etc) which can be referenced in the SOPs.

REPORTING RESULTS/INTERPRETATION

State how the test should be reported, including:

– units to be used and format of reporting (explain

any abbreviations).

– accepted reference range for a quantit ative test.

– action to take if a result is seriously abnormal or

unexpected, e.g. need for veriﬁcation, additional

testing, and, or immediate notiﬁcation of the

result.

– give target turn-around time for issuing the

report (routine and urgent).

_ interpretation comments that should accompany

the test result.

SOURCES OF ERROR

Summarize the important and commonest causes of

an incorrect test result.

Examples: Sample not well mixed, smear too thick

for staining, inaccurate measurement (pipetting) of a

blood or serum sample, clots in anticoagulated

blood sample, air bubbles in the solution when

using a colorimeter or the sides of the cuvette not

being clean and dry, etc.

REFERENCES

List the main source(s) of the information contained

in the SOP, e.g. book, journal, published paper,

manufacturer’s leaﬂet, WHO guidelines or docu-

ment, etc.

What should be included in the appendices

APPENDIX A STAINS/REAGENTS

For each stain and reagent, the following information

is required:

– method of preparation and performance

testing/QC.

– any associated hazard, e.g. chemic al that is

ﬂammable, toxic, harmful, irritant or corrosive.

– labelling speciﬁcations.

– storage requirements and st ability (‘shelf-life’).

– source(s) of chemicals and st ains, ordering infor-

mation (correct name/chemical formula and

where possible, catalogue number), and amount

of each chemical/stain, etc to be kept in stock.

APPENDIX B EQUIPMENT

For each item of equipment the following infor-

mation is required:

– name (including model number) and supplier.

34 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

2.4

– instructions for use, including any safety prec au-

tions.

– daily QC, e.g. cleaning, performance checks.

– details of how to replace components such as a

lamp, fuse, etc.

– maintenance schedule.

– replacement parts to be kept in stock with part

numbers and details of supplier(s).

– trouble-shooting and action to take if the equip-

ment fails.

APPENDIX C HEALTH AND SAFETY

This appendix should include:

– the safe handling and dispos al of specimens.

– decont amination procedures, e.g. use of

chemical agents (disinfectants), autoclaving, etc.

– safe use of chemic als.

– personal safety measures.

– action to take in the event of a ﬁre.

– First Aid procedures.

Note: Some laboratories may prefer to include the above in a

separate Health and Safety Manual.

ADDITIONAL NOTES

Examples of other procedures and information

which are commonly included in a district laboratory

SOP Manual include, laboratory work policies cover-

ing laboratory operating times, emergency out-of-

hours testing arrangements, specimen collection

times, arrangements for the delivery of reports, and

also procedures relating to the packing and trans-

port of specimens to the public health laboratory or

other specialist laboratory.

Important: S OPs must be kept up to date and

reviewed at least annually. Any amendments must

be authorized, referenced, dated, signed, and

brought to the attention of all members of staff.

Users of the laboratory must also receive written

amendments to SOPs when these involve changes

in the ordering of tests, the collection of specimens

and the reporting of tests. No new test should be

introduced without an SOP.

SOURCES OF ERRORS I N DISTRICT LABORATORY

PRACTICE

As previously explained, the preparation and im-

plementation of SOPs will greatly assist in identify-

ing, monitoring, and minimizing errors that lead to

incorrect test results and the waste of resources.

Most errors are associated with:

– Misidentifying a patient.

– Collecting or storing a specimen incorrectly.

– Technical imprecision and inaccuracy.

– Reader variability (see subunit 2.2).

– Adverse laboratory working conditions.

– Misinterpreting test reports (see subunit 2.2).

Patient misidentiﬁcation

In district laboratory practice, the misidentiﬁcation of

a patient is mainly the result of:

● Clerical errors or incomplete identiﬁcation data,

e.g. when names are only used with no check of

an outpatient or inpatient identiﬁcation number

at the time a specimen is collected.

● Language difﬁculties when staff do not speak or

understand sufﬁciently the language or dialect

spoken by the patient.

● Specimen containers that are incorrectly labelled

or when a specimen is misidentiﬁed on a ward

because it is ﬁrst collected in an unlabelled con-

tainer such as a bedpan or sputum pot. Mistakes

can also occur when the writing on a label is

illegible or part erased.

● No reliable check-in system when specimens

reach the laboratory to ensure that the patient

data on the request form is the same as that

written on the label of the specimen container.

Faulty specimens

Caused when:

● A specimen is not correct, is inadequate, or col-

lected at an incorrect time.

● The collection technique is not correct, e.g.

– blood is t aken from an arm in which an

intravenous (IV) infusion is running.

– a wet ne edle and syringe are used to collect

a blood specimen, resulting in haemolysis of

the red cells.

● A container has not been cleaned properly or

dried before being reused, does not contain the

correct anticoagulant or preservative, or is not

sterile when it should be.

● The container cap is loose resulting in loss, evap-

oration, or contamination of the specimen.

● A specimen is unsuitable for testing because it

has been stored incorrectly, has been left for too

long a period in an outpatient clinic, or is too

long in transit before it reaches the laboratory.

● Specimens, particularly blood ﬁlms are not

protected from insects, dust, or direct sunlight.

● A specimen contains drugs, herbal medicines, or

TOTALQUALITY MANAGEMENT OF DISTRICT LAB ORATORY SERVICES 35

2.4

other substances which can interfere with the

performance of a test.

● There is no inspection of specimens when they

reach the laboratory.

Imprecision and inaccuracy

Reliable test results depend on laboratory staff keep-

ing errors of imprecision and inaccuracy to a mini-

mum by good laboratory practice and quality

control. Consistently reliable results depend on the

early detection and correction of errors.

Errors of imprecision

Precision is a measure of reproducibility. Errors of impreci-

sion are often referred to as errors of scatter because they are

irregular, or random. Results differ from the correct result by

varying amounts as explained in subunit 6.2.

Errors of inaccuracy

Accuracy is deﬁned as the closeness of agreement between a

test result and the accepted true value. Errors of inaccuracy

are often referred to as errors of bias because they are consis-

tent, or systematic. All the test results differ from their correct

result by approximately the same amount as explained in

subunit 6.2.

Common causes of imprecision in district laboratory

practice

The following are the commonest causes of

inconsistent random errors:

 Incorrect and variable pipetting and dispensing

caused when:

– pipetting and dispensing te chniques are

poor due to inadequate training, no

supervision of trainees, or careless working.

– pipettes with chippe d ends or unclear

markings are used.

– pipette ﬁllers are difﬁcult to use.

– automatic pipettors and dispensers are not

used correctly or pipettor tips are not ade-

quately cleaned and dried before reuse

(where reuse is possible).

 Inadequate mixing of sample with reagents.

 Samples are not incubated consistently where

incubation of tests is required.

 Glassware or plasticware is not clean or dried

completely before reuse.

 Equipment malfunction caused when:

– lab oratory staff are not trained in the correct

use and maintenance of equipment.

– instrument readings ﬂuctuate due to

unstable power supplies and the equipment

is not ﬁtted with a voltage stabilizer.

– dirty or ﬁnger-marke d cuvettes are used in

colorimeters or the sample contains air

bubbles.

– in hot humid climates, the glass surfaces of

lenses and ﬁlters become damaged when

not protected from fungal growth.

– b attery operated equipment performs errati-

cally because the battery is not sufﬁciently

charged.

 Incomplete removal of interfering substances

such as red cells when performing serum assays.

 Laboratory staff prepare a smear that is too thick

for direct microscopical examination or subse-

quent staining.

 Incorrect reporting of microscopical preparations

and lack of standardization in reporting.

Common causes of inaccuracy in district laboratory

practice

The following are the commonest causes of consis-

tent systematic errors:

 Incorrect or infrequent calibration of a test

method or quantitative tests being read at an

incorrect wavelength (incorrect ﬁlter used).

 Using an automatic pipettor set at an incorrect

volume or one that has been calibrated wrongly.

 Use of control sera that has been wrongly

prepared, incorrectly stored, or used beyond its

expiry date.

 Consistent calculation error.

 Incubating samples at an incorrect temperature

due to the temperature of a waterbath or heat

block being wrongly set and not checked.

 Use of unsatisfactory reagents caused when:

– chemic al reagents and stains are not pre-

pared correctly according to SOPs.

– the quality of water use d in the preparation

of reagents is unsuitable.

– reagents are not prepare d from sufﬁciently

pure chemicals.

– new b atches of reagents are not tested prior

to being used and no controls are used to

check the performance of working reagents.

– reagents are use d beyond their expiry date

without being adequately controlled.

– temperature sensitive reagents deteriorate

because they are not stored at the correct

temperature, are frequently removed from

the refrigerator into a hot environment, or

the refrigerator stops working due to a

36 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

2.4

power failure or running out of gas or

kerosene.

– a reagent b ecomes contaminated when a

dirty or wet pipette is used.

– light sensitive reagents b ecome unﬁt for use

because they are not stored in opaque

containers and protected from light.

– dry, moisture-sensitive reagents and strip

tests deteriorate due to their frequent use in

conditions of high relative humidity, or when

the container is not tightly closed after use

and no desiccant is enclosed.

– st ains are used without controls, are not

ﬁltered when indicated, or absorb moisture

and become unﬁt for use, e.g. alcoholic

Romanowsky stock stains.

 Staff reporting microscopical preparations

incorrectly due to inadequate training with no

control preparations being used, particularly to

check the ability of staff to report:

– Gram st ained smears.

– Ziehl-Ne elsen stained smears.

– Thick and thin staine d blood ﬁlms.

– Cerebrospinal ﬂuid, urine and fae cal

preparations.

Note: Measuring and controlling impre cision and

inaccuracy in quantitative serum assays are

described in detail in subunit 6.2.

Mistakes made by laboratory staff due to

adverse working conditions

Caused when:

 The workload is too high or too low:

Workload capacity of a laboratory

The workload must be matched to the number of staff and

their experience, and to the size of the laboratory and its

facilities. Workload is usually measured in terms of time

required for a test to be completed. When workload is ex-

cessive, the testing of specimens becomes unreliable and

safety measures tend to be ignored. Too little work can

also lead to unreliable test results due to lack of concen-

tration.

 The laboratory is small with insufﬁcient or poorly

lit working areas and is not sufﬁciently ventilated

or screened from direct sunlight.

 Laboratory staff become professionally isolated

and lack motivation when they receive little

support and encouragement.

 There are too many interruptions or when there

is excessive noise from nearby OPD waiting

areas or radios.

 When there are too many urgent test requests.

 District hospital laboratory staff become fatigued

or sick (e.g. with malaria) due to many night

emergency calls.

Note: Monitoring the workload and working

conditions of district laboratory personnel forms an

integral part of health and safety and the total

quality management of district laboratory services.

EXTERNAL QUALITY ASSE SSMENT (E QA)

Although steps may be taken in a laboratory to en-

sure test results are reliable, an objective system of

assessing a laboratory’s ability to do this to a satis-

factory standard is recommended, i.e. an external

quality assessment (EQA) scheme.

Participation in external quality assessment

schemes should always be regarded as additional to

internal quality control. EQA must never be a sub-

stitute for internal QC because it can only assess

past performance when test results have already

been reported and acted on.

EQA for outreach laboratories

The district laboratory coordinator, with the assist-

ance of the senior district hospital laboratory ofﬁcer,

should implement a basic EQA scheme for outreach

laboratories covering the main tests performed, par-

ticularly those where errors are more likely to occur

such as the reporting of microscopical preparations,

measurement of haemoglobin, and testing of urine.

For most outreach laboratories, EQA will be most

practically implemented during the regular visit of

the district laboratory coordinator. This will give the

opportunity for errors to be investigated on-site and

corrected rapidly.

EQA for the district hospital laboratory

Comprehensive EQA schemes in which the results

from different district hospital laboratories are

compared objectively are not yet operating in most

tropical and developing countries due to lack of

commitment, inadequate resourcing, too few labora-

tory personnel trained in QA, and difﬁculties in

transporting and mailing pathological specimens.

In recent years, the World Health Organization

has issued guidelines on the role of laboratory EQA

schemes and how developing countries can

participate in WHO International External Quality

Assessment Schemes (IEQASs).

In the absence of national EQA schemes, the dis-

trict laboratory coordinator should prepare control

materials for use in district hospital laboratories,

particularly control preparations for microscopical

TOTALQUALITY MANAGEMENT OF DISTRICT LAB ORATORY SERVICES 37

2.4–2.5

investigations, control serum for clinical chemistry

assays, control cultures for microbiology, control

blood for checking the measurement of haemoglo-

bin and other haematology tests, and controls for

testing the competence of staff in blood typing and

compatibility testing.

The district laboratory coordinator should moni-

tor regularly whether SOPs and quality control pro-

cedures are being implemented correctly in the

district hospital laboratory and also the quality and

consistency of reporting and recording test results.

Correcting errors associated with poor

work performance

Most of the errors resulting in incorrect test re-

sults in district laboratories can be resolved by:

● Using SOPs with adequate QC and

reference materials.

● Improving working practices and laboratory

management.

● Monitoring laboratory working conditions

and workload.

● Supporting district laboratory personnel, i.e.

regular visits by the district laboratory

coordinator.

● Organizing an effective district quality

assessment scheme.

● Changing to competency-based training of

laboratory personnel and implementing

performance assessment and continuing

education of district laboratory staff.

● Improving communication between labora-

tory staff and those requesting laboratory

tests and interpreting test results.

2.5 SI units

Following World Health Organization recommen-

dations, SI units (Système International d’Unités) are

used in this publication:

– in test methods,

– preparation of reagents,

– reporting of test results.

The International System of Units has been devel-

oped and agreed internationally. It overcomes

language barriers, enabling an exchange of health

information within a country and between nations to

be made without the misunderstandings which arise

when each country, or even a separate hospital

within a country, uses its own units of measurement

for reporting tests. It is therefore important for health

authorities and laboratories to adopt SI units.

SI BASE UNITS

The International System of Units is based on the

metre-kilogram-second system and replaces both

the foot-pound-second (Imperial) system and the

centimetre-gram-second (cgs) system.

The seven SI base units from which all the other

units are derived are as follows:

SI base units Symbol Quantity measured

metre m length

kilogram kg mass

second s time

mole mol amount of substance

ampere A electric current

kelvin K temperature

candela cd luminous intensity

SI DERIVEDUNITS

SI derived units consist of combinations of base

units:

SI derived unit Symbol Quantity measured

square metre m

area

cubic metre m

volume

metre per second m/s speed

Special names have been given to those derived

units with complex base combinations:

Name derived unit Symbol Quantity measured

Hertz Hz frequency

joule J energy, quantity of heat

newton N force

pascal Pa pressure

watt W power

volt V electric potential difference

degree Celsius °C Celsius temperature

SI UNIT PREFIXES

To enable the measurement of quantities larger or

smaller than the base units or derived units, the SI

38 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

2.5

Unit System also includes a set of preﬁxes. The use

of a preﬁx makes a unit larger or smaller.

Example

If the preﬁx milli (m) is put in front of the metre this

would indicate that the unit should be divided by a

thousand, i.e. 10

3

. The way of expressing this

would be 10

3

m, or mm.

Ifhowever the preﬁx kilo (k)were used this would

indicate that theunit should be multiplied by a thou-

sand, i.e.10

.This would be expressed 10

m,or km.

The range of SI unit preﬁxes commonly used in

laboratory work are listed as follows:

Preﬁx Symbol Function

DIVIDE BY:

deci d 10

1

centi c 10

2

100

milli m 10

3

1000

micro  10

6

1000 000

nano n 10

9

1000 000000

pico p 10

12

1000 000000 000

femto f 10

15

1000 000000 000000

MULTIPLY BY:

kilo k 10

1000

VOLUME: LITRE (L OR l)

The SI derived unit of volume is the cubic metre

). Because this is such a large unit, the litre (l or

L) although not an SI unit, has been recommended

for use in the laboratory.

Volume measurements are made in litres or multi-

ples and submultiples of the litre, e.g. dl (10

1

l),

ml (10

3

l), l (10

6

l).

One litre is therefore equivalent to 10 dl,

1000 ml or 1000000 l. One dl is e quivalent to

100 ml, and 1 ml to 1000 l.

Old unit SI unit

100 ml dl

cc ml or cm

lambda l

—nl

lpl

Useful volume table

1 dl 10

1

l (0.1 l) or 100 cm

, formerly 100 ml

1 ml  10

3

(0.001 l) or 1 000 l

1 l  10

6

(0.000 001 l or 1 mm

)

1 nl 10

9

l (0.000 000 001 l)

1 pl 10

12

l (0.000 000 000 001 l)

1 ﬂ 10

15

1 l  10 dl

1 000 ml

1 000 000 l

1 000 000 000 nl

1 pint  0.568 l

1 l  1.760 pints or 0.22 gallons

WEIGHT: GRAM (g)

The kilogram (kg) is the SI unit for mass and the

gram (g) is the working unit.

Formerly the gram (g) was written gramme, or gm.

Mass measurements are made in grams or in multi-

ples and submultiples of the gram, e.g. mg (10

3

g),

g (10

6

g), ng (10

9

g), pg (10

12

g).

One g is therefore equivalent to 1000 mg,

1000 000 g, or 1000 000000 ng. One mg is

equivalent to 1000 g.

Old unit SI unit

k, kilogramme kg

gm, gramme g

mgm mg

gamma g

mug ng

gpg

Useful weight table

1 kg  10

g (1 000 g)

1 mg  10

3

g (0.001 g) or 1 000 g

1 g  10

6

g (0.000 001 g)

1 ng  10

9

g (0.000 000 001 g)

1 pg  10

12

g (0.000 000 000 001 g)

1 g  1 000 mg

1 000 000 g

1 000 000 000 ng

1 000 000 000 000 pg

1 kg  2.205 lb

Tests now reported in g/l include: albumin, total pro-

tein, haemoglobin (although dl is still used), mean

cell haemoglobin concentration.

LENGTH: METRE (m)

The SI unit for length is the metre (m) and mea-

surements of length are made in metres or in mm

(10

3

m), m (10

6

m), nm (10

9

m).

One m is therefore equivalent to 1000 mm or

1000 000 m and 1 mm is equivalent to 1000 m

or 1000 000 nm.

Old unit SI unit

m nm

 (micron) m

TOTALQUALITY MANAGEMENT OF DISTRICT LAB ORATORY SERVICES 39

2.5

Useful length table

1 dm  10

1

m (0.1 m)

1 cm  10

2

m (0.01 m), 10 mm, 10 000 m

1 mm  10

3

m (0.001 m), 1 000 m

1 m  10

6

m (0.000 001 m)

1 nm  10

9

m (0.000 000 001 m)

1 km  1 000 m (10

1 m  10 d m

100 cm

1 000 mm

1 000 000 m

1 000 000 000 nm

1 m  3.281 feet

1 km  0.62 137 mile

1 inch  2.54 cm

AMOUNT OF SUBSTANCE: MOLE (mol)

The mole (mol) is the SI unit for amount of sub-

stance and measurements of the amounts of sub-

stances are made in moles, or in mmol (10

3

mol),

mol (10

6

mol), or nmol (10

9

mol).

One mol is therefore equivalent to 1 000 mmol,

1 000 000 mol, or 1 000 000 000 nmol. One

mmol/l is equivalent to 1 000 mol/l.

Formerly, the results of tests expressed in mmol/l

or mol/l were expressed in mg/100 ml or g/100

ml. The formula used to convert mg/100 ml to

mmol/l is as follows:

mmol/l 

Where the molecular weight of a substance cannot

be accurately determined (e.g. albumin), results are

expressed in g/l.

Old unit SI unit

M mol

mEq mmol

M mol

nM nmol

Useful amount of substance table

1 mmol  10

3

mol (0.001 mol), 1 000 mol

1 mol  10

6

mol (0.000 001 mol), 1 000 nmol

1 nmol  10

9

mol (0.000 000 001 mol)

1 mol  1 000 mmol

1 000 000 mol

1 000 000 000 nmol

Tests reported in nmol/l, mol/l, mmol/l include:

nmol/l: thyroxine

mol/l: bilirubin, creatinine, iron

mmol/l: calcium, glucose, urea, cholesterol, sodium,

potassium

mg/100 ml 10



molecular weight of substance

Mole per litre solutions (mol/l)

A mole per litre (mol/l) solution contains one mole

of solute dissolved in and made up to 1 litre with

solvent.

Mole

A mole is deﬁned as the amount of substance of a system

which contains as many elementary units (atoms, molecules,

or ions) as there are carbon atoms in 0.012 kg of the pure

nuclide carbon12 (

C).

To avoid confusion, mole per litre solutions should

not be referred to as molar or M solutions. The in-

ternationally agreed meaning of the word molar as

used in chemistry is ‘divided by amount of sub-

stance’, i.e. divided by mole. Molar cannot be

applied therefore to mole per litre solutions as these

refer to mole divided by litre (mol/l). The term

molarity should be discontinued.

Conversion of a normal solution into a mol/l solution

To change a normal solution into a mol/l solution,

use the formula:

mol/l solution 

INTERNATIONALUNIT (U)

This unit is used to express catalytic enzyme activity

corresponding to mol/minutes. Units for measur-

ing enzyme activity have in the past been given the

names of the person who developed the different

techniques, e.g. Somogyi, King-Armstrong, Bessey-

Lowry, Reitman-Frankel, and Karmen. In an attempt

to standardize the reporting of enzyme activity a unit

of measurement has been introduced called the

International Unit (U)

International Unit

An International Unit of enzyme activity is that

amount of enzyme which under deﬁned assay con-

ditions will catalyze the conversion of 1 mol of

substrate per minute. Results are expressed in

International Units per litre (U/l).

In accordance with this deﬁnition the assay con-

ditions for enzyme analysis must be speciﬁed (see

subunit 6.2).

Enzyme activities now expressed in U/l include

alkaline phosphatase and aspartate aminotransferase.

PRESSURE AND TEMPERATURE

The SI unit used for measuring pressure is the

pascal (Pa).

Normality of solution



Valence of substance

40 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

2.5–2.6

Approximate conversions

 kPa

lb/sq inch  6.895  kPa

Temperature

The SI unit for measuring Celsius temperature is

degrees Celsius (°C).

Useful conversions

To convert °C to °F:

multiply by 9, divide by 5, and add 32.

To convert °F to °C:

subtract 32, multiply by 5, and divide by 9.

0°C  32°F

10° C  52°F

20°C  68°F

30°C  86°F

36.9°C  98.4°F

40°C  104°F

50°C  122°F

100°C  212° F

2.6 Guidelines for preparing

stains and chemical reagents

As discussed in subunit 2.4, preparing and storing

reagents incorrectly are important causes of unreli-

able test results. This subunit provides guidelines on

the correct preparation of stains and chemical

reagents to ensure quality of work and prevent

waste of resources.

Errors in the preparation of stains and

reagents

Most errors that occur in the preparation of stains

and reagents are due to:

 Incorrect preparation techniques.

 Calculating incorrectly the weight or volumes of

constituents.

 Making dilution errors.

Important: Following the preparation of a stain or

chemical reagent, its performance must be checked

before it is put into routine use. Standard operating

procedures must be implemented for the prep-

aration, control, and safety of reagents used in

district laboratories.

mmHg  2



Health and safety: Precautions that need to be

taken when using Harmful, Irritant, Toxic, Corrosive,

and Flammable chemic als are described in subunit

3.5.

PREPARATIONTECHNIQUE

When preparing a solution decide whether the sol-

ution requires an accurate volumetric preparation,

e.g. a calibrant (standard), or a less accurate method

of preparation, e.g. a stain.

Preparing accurate solutions

 Use a balance of sufﬁcient sensitivity (see 4.5).

Weigh the chemical as accurately as possible.

The chemical should be of an analytical reagent

grade. Hygroscopic and deliquescent chemicals

need to be weighed rapidly.

Analytical reagents

Errors due to the use of impure chemicals can be avoided by

purchasing chemicals that are labelled Analar, Univar, AR

(Analytical Reagent), or GR (Guaranteed Reagent). LG

(Laboratory Grade) reagents are of lower purity but may be

suitable for some purposes. Technical and Industrial grade

chemicals, although less expensive, must not be used to pre-

pare calibrants or any reagent which requires a pure chemical.

 Use calibrated, chemically clean glassware.

 Read carefully the graduation marks and other

information on ﬂasks and pipettes, for example

check whether a pipette is of the containing (rins-

ing-out) type or of the delivery (non-rinsing-out)

type. It is best to use a delivery type. Instructions

when using a pipettor can be found in subunit

4.6.

 Use a funnel to transfer the chemical from the

weighing container to a volumetric ﬂask. Wash

any chemical remaining in the container into the

ﬂask with a little of the solvent.

 Make the solution up to its ﬁnal volume. If warm,

make up to volume only when the solution has

cooled to the temperature used to graduate the

ﬂask (written on the ﬂask).

 To avoid over-shooting the graduation mark, use

a Pasteur pipette or wash-bottle to add the ﬁnal

volume of solvent to the ﬂask.

 Make sure the bottom of the meniscus of the

ﬂuid is on the graduation mark when viewed at

eye level (see Fig. 2.5).

 Mix the solution well by inverting the ﬂask at

least twenty times.

 Store reagents in completely clean containers

that have leak-proof airtight screw-caps or stop-

TOTALQUALITY MANAGEMENT OF DISTRICT LAB ORATORY SERVICES 41

2.6

pers. Use brown bottles or opaque plastic con-

tainers for storing light sensitive reagents. Before

transferring a solution to its storage container,

ﬁrst rinse out the container with a little of the

solution.

 Label the container clearly with a water-proof

marker. Include the full name of the reagent, its

concentration, date of preparation and if relevant

its expiry date. If it requires refrigeration, state

‘Store at 2–8°C’. Protect the label by covering it

with clear adhesive tape. If a reagent is

Harmful, Irritant, Toxic, Corrosive, or Flammable,

indicate this on the container label (see subunit

3.5).

 Protect all reagents from sunlight and heat. Store

light sensitive reagents and stock solutions of

stains in the dark.

Preparation of calibrating solutions (standards)

When preparing calibrants the following are

important:

– Always use pure chemicals. The use of impure

low grade chemicals can lead to serious errors in

test results.

– Avoid weighing a very small quantity of a cali-

brant substance. Instead prepare a concentrated

stock solution which can be diluted to make

working solutions.

– Use good quality distilled water. Electrolyte

calibrants require deionized water.

– Use calibrated glassware and a volumetric

technique as described previously.

– Use a control serum to check the performance of

the calibrant solutions.

Whenever possible, calibrants should be prepared

and standardized in a regional or control laboratory

and distributed with instructions for use to district

laboratories.

Meniscus of ﬂuid

on the graduation

mark

Neck of Flask enlarged

Fig. 2.5 How to read the level of a ﬂuid

Preparing stains

There is no need to use expensive volumetric glass-

ware when preparing stains.

 Weigh the dye in a small container and transfer

the weighed dye direct to a leak-proof storage

container, preferably a brown bottle.

 Add any other ingredients and the volume of sol-

vent as stated in the method of preparation, and

mix well. Adding a few glass beads will help the

dye to dissolve more quickly. For some stains

heat can be used to dissolve the dye (this will be

stated in the method of preparation).

Note: Instead of measuring the volume of sol-

vent each time the stain is prepared, it is more

practical to mark the side of the container with

the volume which needs to be added.

 Transfer part of the stain to a stain dispensing

container, ﬁltering it if required. Always use dis-

pensing containers with tops that can be closed

when not in use.

 Label the container in a similar way to that

described previously.

 Store as instructed in the method of preparation.

Always protect stock containers of stain from

direct sunlight.

Water used in preparing solutions and stains

For all the reagents described in Appendix 1, de-

ionized water can be used instead of distilled water.

For most stains and reagents not used in clinical

chemistry tests, boiled ﬁltered rain water or boiled

water ﬁltered through a Sterasyl c andle ﬁlter (see

subunit 4.4) can be used if distilled or deionized

water is not available.

Note: A method of preparing chemically pure water

in district laboratories is described in subunit 4.4.

Guidelines for handling chemicals and

reagents

 Handle chemicals and reagents with care par-

ticularly those that are Flammable, Toxic, Harmful,

Irritant, Corrosive (see subunit 3.5). Wear appro-

priate protective clothing.

 Always read the health and safety information on

the labels of containers.

 Do not mouth-pipette reagents. Instead, use a

pipette ﬁller, automatic dispenser or pipettor.

 Always check that an opened bottle of chemical

is completely ﬁnished before starting a new one.

 Keep containers tightly closed.

 Do not return excess chemical to a stock bottle.

42 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

2.6

 Make sure all chemicals and reagents are

labelled clearly.

 Store chemicals and reagents correctly (see sub-

unit 3.5).

Deliquescent chemicals

Chemicals such as calcium chloride, potassium carbonate,

phenol, and sodium hydroxide are very soluble in water and

become moist when exposed to damp air. They become dis-

solved in the moisture and go on taking in moisture until the

vapour pressure of the solution equals the pressure of the

water in the atmosphere. Such chemicals are said to be deli-

quescent. They can be used as drying agents (desiccants) in

desiccators.

Hygroscopic chemicals

A substance which absorbs water from the air but does not

dissolve in the water it absorbs is referred to as hygroscopic,

e.g. sodium carbonate.

CALCULATINGCORRECTLY

In the preparation of solutions, calculation errors

commonly occur due to:

 Simple errors in calculating amounts and vol-

umes, most of which can be prevented by

routinely rechecking the calculations.

 Not using the correct formula when preparing a

mol/l solution.

 Not using the correct formula when diluting a

solution.

Useful table

1 g 1000 mg 1 litre 1 000 ml

1 g 1000 000 g1 ml 1 000 l

0.1 g  100 mg 1 mol 1 000 mmol

0.01 g  10 mg 1 mol  1 000 000 mol

1000 g 1 mg 1 mmol  1000 mol

Preparing mol/l solutions

Based on the fact that chemicals interact in relation

to their molecular masses it is recommended that

the concentration of solutions be expressed in terms

of the number of moles of solute per litre of solution

(see subunit 2.5 which describes the use of SI units).

Only when the relative molecular mass of a sub-

stance is not known, should the concentration of

such a substance in solution be expressed in terms

of mass (weight) concentration, i.e. grams or

milligrams per litre (per 100 ml should be discontin-

ued).

To prepare a mol/l solution, use the following

formula:

Required mol/l solution  Molecular mass of substance 

Number of grams to be dissolved in 1 litre of solution.

When calculating the molecular mass of a chemical

it is important to check whether it contains water of

crystallization. For example, hydrated copper sul-

phate (blue) has a formula of CuSO

·5H

O, which

means it contains 5 molecules of water per mole-

cule. The molecular masses of some hydrated and

anhydrous (without water of crystallization) chemi-

cals are listed in Appendix III.

EXAMPLES

 To make 1 litre of sodium chloride (NaCl), 1 mol/l:

Required mol/l concentration  1

Molecular mass of NaCl  58.44

Therefore 1 litre NaCl, 1 mol/l contains:

1  58.44  58.44 g of the chemical dissolved

in 1 litre of solvent.

Note: When writing mol/l solutions, the concentration is

written after the name of the substance.

 To make 1 litre of sodium chloride (NaCl), 0.15

mol/l (physiological saline):

Required mol/l concentration  0.15

Molecular mass of NaCl  58.44

Therefore 1 litre NaCl, 0.15 mol/l cont ains:

0.15 58.44  8.77 g of the chemical dissolved

in 1 litre of solvent.

 To make 50 ml of sodium chloride (NaCl), 0.15

mol/l (physiological saline):

Required mol/l concentration  0.15

Molecular mass of NaCl  58.44

Therefore 50 ml NaCl, 0.15 mol/l cont ains:

 0.438 g of NaCl

dissolved in 50 ml of

solvent.

Note:In some publications the decimal point is written as

a comma, e.g. 0.15 would be written as 0,15.

Formula to convert a percentage solution to a

mol/l solution

To change a percentage solution into a mol/l sol-

ution, use the formula:

mol/l solution 

EXAMPLES

 To convert a 4% w/v sodium hydroxide (NaOH)

solution into a mol/l solution:

Gram % solution  4

Molecular mass of NaOH  40

Conversion to mol/l:  1

Therefore 4% w/v NaOH is equivalent to a

1 mol/l NaOH solution.

4  10



g% (w/v) solution 10



molecular mass of substance

0.15  58.44  50



1 000

TOTALQUALITY MANAGEMENT OF DISTRICT LAB ORATORY SERVICES 43

2.6

 To convert a 0.9% w/v sodium chloride (NaCl)

into a mol/l solution:

Gram % solution  0.9

Molecular mass of NaCl  58.44

Conversion to mol/l: 0.15

Therefore 0.9% w/v NaCl is equivalent to a

0.15 mol/l NaCl solution.

Conversion of a normal solution into a mol/l

solution

To change a normal solution into a mol/l solution

use the formula:

mol/l solution 

EXAMPLES

 To convert 0.1 N (N /10) hydrochloric acid (HCl)

into a mol/l solution:

Normality of solution  0.1

Valence of Cl (in HCl)  1

Conversion to mol/l:  0.1

Therefore 0.1 N HCl is equivalent to

0.1 mol/l HCl solution.

 To convert 1 N sodium carbonate (Na

) into

a mol/l solution:

Normality of solution  1

Valence of CO



(in Na

)  2

Conversion to mol/l:  0.5

Therefore 1 N Na

is equivalent to

0.5 mol/l Na

solution.

Note: The relative molecular masses (molecular

weights) of some of the more commonly used sub-

stances and the atomic masses and valencies of

some of the elements, are listed in Appendix III.

DILUTING CORR ECTLY

In the laboratory it is frequently necessary to dilute

solutions and body ﬂuids. To dilute a solution or

body ﬂuid means to reduce its concentration. A

weaker solution can be made from a stronger

solution by using the following formula:

Volume (ml) of stronger solution required 

where:

C  Concentration of solution required

V  Volume of solution required

S  Strength of the stronger solution

C V



0.1



Normality of solution



Valence of substance

0.9  10



58.44

EXAMPLES

 To make 500 ml sodium hydroxide (NaOH), 0.25

mol/l from a 0.4 mol/l solution:

C  0.25 mol/l, V  500 ml, S  0.4 mol/l

ml of stronger solution required:

 312.5

Therefore, measure 312.5 ml NaO H, 0.4 mol/l,

and make up to 500 ml with distilled water.

 To make 1 litre hydrochloric acid (HCl), 0.01 mol/l

from a 1 mol/l solution:

C  0.01 mol/l, V  1 litre, S  1 mol/l

ml of stronger solution required:

 10

Therefore, measure 10 ml HCl, 1 mol/l, and

make up to 1 litre with distilled water.

 To make 100 ml glucose, 3 mmol/l in 1 g/l ben-

zoic acid from glucose 100 mmol/l solution:

C  3 mmol/l, V  100 ml, S  100 mmol/l

ml of stronger solution required:

 3

Therefore, measure 3 ml of glucose, 100 mmol/l,

and make up to 100 ml with 1 g/l benzoic acid.

 To make 500 ml sulphuric acid (H

), 0.33

mol/l from concentrated sulphuric acid which has

an approximate substance concentration of 18

mol/l:

C  0.33 mol/l, V  500 ml, S  18 mol/l

ml of stronger solution required:

 9.2

Therefore, measure 9.2 ml concentrated H

and slowly add it to about 250 ml of distilled

water in a volumetric ﬂask. Make up to 500 ml

with distilled water.

Diluting body ﬂuids

To prepare a dilution or series of dilutions of a body

ﬂuid:

EXAMPLES

 To make 8 ml of a 1 in 20 dilution of blood:

Volume of blood required: 0.4 ml

Therefore, to prepare 8 ml of a 1 in 20 dilution,

add 0.4 ml of blood to 7.6 ml of diluting ﬂuid.

 To make 4 ml of a 1 in 2 dilution of serum in

physiological saline:



0.33  500



3  100



100

0.01 1 000



0.25  500



0.4

44 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

2.6

Volume of serum required:  2.0 ml

Therefore, to prepare 4 ml of a 1 in 2 dilution,

add 2 ml of serum to 2 ml of physiological saline.

Calculating the dilution of a body ﬂuid

To calculate the dilution of a body ﬂuid:

EXAMPLES

 Calculate the dilution of blood when using 50 l

(0.05 ml) of blood and 950 l (0.95 ml) of

diluting ﬂuid:

Total volume of body ﬂuid and diluting ﬂuid:

50  950  1 000 l

Therefore, dilution of blood: 20

i.e. 1 in 20 dilution.

 Calculate the dilution of urine using 0.5 ml of urine

and 8.5 ml of diluting ﬂuid (physiological saline):

Total volume of urine and diluting ﬂuid:

8.5  0.5  9.0 ml

Therefore, dilution of urine:  18

i.e. 1 in 18 dilution.

PROPERTIESOF COMMONLYUSED ACIDS AND BASES

An acid is a substance that liberates hydrogen ions

in solution and acts as a proton donor (donating H



Acids turn litmus red, and react with carbonates

to produce the gas carbon dioxide. When reacted

with a base, an acid produces a salt and water. Most

acids are corrosive.

Sulphuric acid, nitric acid, and hydrochloric acid

are referred to as strong acids because they ionize

almost completely in solution with very few intact

molecules of the acid remaining. Ionization is the

dissociation of a substance in solution into electrically

charged atoms known as ions. Lactic acid and glacial

acetic acid are referred to as weak acids, because

they ionize very little in solution.

The properties of the commonly used acids are

as follows:

Sulphuric acid (H

): Has a relative density of

1.840, molecular mass 98.08, and concentration

95–97% by weight.

It is very corrosive, viscous, oily, and reacts vio-

lently with water (hygroscopic). See also subunit 3.5.

Hydrochloric acid (HCl): Has a relative density of

1.190 and molecular mass 36.46. The concentrated

acid contains 37% by weight of the gas hydrogen

9.0



0.5

1 000



chloride. It is fuming and corrosive. See also subunit

3.5.

Nitric acid (HNO

): Has a relative density of 1.510,

molecular mass 63.01, and concentration about 99%

by weight. It is fuming, corrosive, stains the skin

yellow-brown, and is a powerful oxidizing agent. See

also subunit 3.5.

Approximate molarity (mol/l) of some acids

Concentrated acid Approx. mol/l

Acetic acid, glacial, 99.6% w/w: 17.50

Hydrochloric acid, 1.16, 32% w/w: 10.20

1.18, 36% w/w: 11.65

Nitric acid, 1.42, 70% w/w: 15.80

Sulphuric acid, 1.84, 97% w/w: 18.00

To make approx. 1 mol/l solutions from concentrated acids

Concentrated acid ml diluted to 1 litre

Acetic acid, (glacial), 99.6% w/w 58 ml

Hydrochloric acid, 32% w/w 98 ml

36% w/w 86 ml

Nitric acid, 70%, w/w 63 ml

Sulphuric acid, 97% w/w 56 ml

BASES

A base is a substance that liberates hydroxide ions in

solution and can accept a proton.

Alkaline solutions have a soapy feel, turn litmus

blue, and react with an acid to form a salt and water.

The common bases include oxides and hydrox-

ides of metals such as sodium, potassium, calcium,

lead, iron, and copper. The oxides of potassium,

sodium, and calcium dissolve in water to form

alkalis.

Sodium hydroxide and potassium hydroxide are

referred to as strong alkalis because they dissociate

completely into cations and hydroxide ions in water.

Sodium hydroxide is the most commonly used

alkali in district laboratories.

Sodium hydroxide (NaOH)

NaOH (supplied as pellets) is a corrosive deliques-

cent chemical with a molecular mass of 40.0.

When preparing sodium hydroxide solutions, it is

necessary to dissolve small amounts of pellets at a

time in water to avoid the production of excessive

heat.

Preparation of NaOH solutions of different molarities

NaOH required in 1 litre Approx. mol/l

4 g 0.12

10 g 0.25

16 g 0.42

40 g 1.25

200 g 5.25

TOTALQUALITY MANAGEMENT OF DISTRICT LAB ORATORY SERVICES 45

2.6

Note:The volumes must be made up to 1 litre after the

solutions have cooled to room temperature.

ACID BASE REACTION S

Examples of chemical reactions involving acids and

bases include:

Acid Base Salt Water





 Na





→





 H

Hydrochloric Sodium Sodium Water

acid hydroxide chloride

COO





 Na





→

COO





 H

Acetic Sodium Sodium Water

acid hydroxide acetate

PK OF ACIDS AND BASES

The strength of an acid or base is determined by its

pK which is deﬁned as the negative logarithm (to the

base 10) of the ionization constant (K):

pK log

For example, a strong acid has a low pK value

whereas a weak acid has a high pK. The higher the

pK value the weaker the acid.

Neutralization reactions

The process of adding an acid to a base, or a base to an acid,

to give a neutral solution consisting of a salt and water, is

known as neutralization. The neutral solution contains equal

numbers of hydroxide and hydrogen ions.

Hydrolysis

Hydrolysis is the chemical decomposition of a substance by

water, with the water also being decomposed. Salts of weak

acids, weak bases, or both, are partially hydrolyzed to form

molecules of weak electrolytes in solution. An ester may be

hydrolyzed to form an alcohol and an acid.

PH OF SOLUTIONS

Neutral solutions have equal concentrations of

hydrogen ions and hydroxide ions. Pure water is

neutral because it ionizes very slightly to give one

hydroxide ion and one hydroxide ion for each

molecule ionized.

Whether a solution is acidic or alkaline, there are

always both H



and OH



ions present. It is the pre-

dominance of one type of ion over the other that

determines the degree of acidity and alkalinity.

When referring to the degree of acidity or alkalinity

of solutions it is usual to refer only to the hydrogen

ion concentration.

Pure water at 25 °C contains 0.000 000 1 g, or

7

g, of hydrogen ions per litre.

Because the molecular mass of a hydrogen ion is

1, the hydrogen ion concentration of pure water can

be expressed as follows:



] (Pure water) 1 10

7

mol/l

There is however no SIunit preﬁx for 10

7

and

therefore the preﬁx nano (n) which means 10

9

used. The SIunit formula is written:



] (Pure water) 100 10

9

mol/l



] (Pure water) 100nmol/l

Normal blood, being slightly alkaline (pH about

7.4), contains fewer hydrogen ions than pure water:



] (Blood) 40 nmol/l

XPRESSING HYDROGEN ION CONCENTRATION

As a convenient way of expressing hydrogen ion

concentration, the symbol pH was introduced by

Sorensen in 1909. pH is deﬁned as the negative

value of the logarithm to the base 10 of the hydro-

gen ion concentration:

pHlog



]

The pH of pure water can be expressed as follows:

pH (pure water) log

pH (pure water) 7 (neutral)

The pH scale is usually expressed from 0 to 14 units,

with a pH of less than 7 indicating acidity and a pH

above 7 indicating alkalinity:

Acidity Neutral Alkalinity

⏐

pH 0 pH 7 pH 14

pH can be measured using pH papers which give an

approximate pH value, or by using a colorimeter

with indicators and a series of coloured standards, or

a pH meter which provides the most accurate

method of determining pH.

UFFER SOLUTION S

Buffer solutions contain a mixture of a weak acid

and a salt of a strong base, or a weak base and its

salt with a strong acid.

Due to their composition, buffers are able to resist

changes in pH. For example, if a small amount of

hydrochloric acid is added to a buffer solution the

hydrogen ion content does not increase very much

because it combines the weak base of the buffer

resulting in only a slight decrease in pH.



7

46 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

2.6

A buffer has its highest buffering ability when its pH

is equal to its pK.

Buffers are used in clinical chemistry when the pH

needs to be carefully controlled, e.g. when measur-

ing enzyme activity.

INDICATORS

Indicators are substances that give different colours

or shades of colour at different pH values. For

example, phenol red changes from yellow at pH 6.8

to a deep red at pH 8.4.

Indicators are used to determine the pH of liquids

and the ‘end-point’ of acid-base titrations. When

titrating a strong or a weak acid with a strong base,

an indicator is selected which changes colour at an

alkaline pH, e.g. phenolphthalein. When titrating a

strong or weak base with a strong acid, an indicator

is used which changes colour at an acid pH, e.g.

methyl orange.

PURCHASINGCHEMICALS, REAGENTS, STAINS

Whenever possible, chemicals, reagents and stains

for use in district laboratories should be purchased

at regional or central level to promote standardiz-

ation and beneﬁt from bulk-purchasing prices. If this

is not possible the following guidelines are

recommended when ordering chemicals, reagents

and stains.

Ordering chemicals and reagents

 Obtain a catalogue and price list from the

manufacturer or local supplier.

 When ordering, use the correct name and when-

ever possible give the chemical formula. Some

chemicals can be obtained in both hydrated and

anhydrous form.

 Check that the amount you are ordering is avail-

able. Unless a chemical is very expensive, it is

unlikely to be available in amounts under 100 g.

Many chemicals may only be available in

quantities of 250 g or 500 g.

 Check that the shelf-life of the chemical is

acceptable and the conditions of storage can be

met to ensure stability and safety in transit and in

the laboratory.

 If needing to import a chemical, make sure

national regulations will permit importation and

that the chemical is not listed by the manufac-

turer as unstable and therefore unsuitable for

export (this information will be in the manufac-

turer’s catalogue).

 Check the price of the chemical and terms of

purchase. Some chemical companies and sup-

pliers have a minimum order value making it

unaffordable to buy a single or a few chemicals

at a time.

Ordering dyes and ready-made stains

When purchasing dyes and stains it is also important

to obtain a supplier’s catalogue:

– to ensure the correct name of the dye or stain is

used when ordering.

– to know the form available, e.g. powder, liquid

concentrate, or liquid ready-made stain, and to

know the quantities available.

– to check stability and storage requirements.

Most of the aqueous-based stains used in micro-

biology and parasitology can be easily prepared

locally from powders. The alcohol-based stains used

in haematology, however, are less easily made local-

ly when water-free methanol or ethanol are difﬁcult

to obtain. In these situations it may be more appro-

priate and cost-effective to purchase the ready-made

stains to ensure quality. Only small volumes of the

stains are used in the working solutions.

2.7 Communicating

effectively

By deﬁnition, communication is the accurate passing

on or sharing of information. In district laboratory

work there are three main ways of communicating

information:

– by writing

– by speaking

– by actions.

WRITTEN COMMUNICATION

To be effective, written communication needs to be:

– presented legibly and neatly,

– expressed clearly and simply.

Writing legibly and neatly

In laboratory work, serious consequences may result

when hand-written ﬁgures or words are read

incorrectly because of poor handwriting or untidy

corrections. An illegibly written report may result in

TOTALQUALITY MANAGEMENT OF DISTRICT LAB ORATORY SERVICES 47

2.6–2.7

a patient receiving incorrect treatment. The presen-

tation of well-written and neat reports not only

avoids errors, misunderstandings, and frustrations,

but also inspires conﬁdence in those using the lab-

oratory. Before issue, all reports should be checked

by the most senior member of staff. To promote

standardization and neatness of reporting, the use of

rubber stamps is recommended as described in sub-

unit 2.2. Recording of patient data and the results of

tests in laboratory registers must be done with care

as also the recording of quality control data.

Writing clearly and simply

Opportunities for laboratory personnel to develop

written skills should be provided during training.

A trained laboratory ofﬁcer needs to know how

to write clear reports and instructions with regard to

standard operating procedures, use of equipment,

preparation of reagents, safety measures, collection

of specimens, laboratory policies, notices (memos),

agendas for meetings, work reports, budgets, and

requisitioning of laboratory supplies.

Laboratory personnel should be encouraged to

contribute to newsletters and journals.

Computer skills:Where facilities exist, laboratory staff should

be trained in basic computer skills, including the use of e-mail

and how to process data and access information from relevant

websites via the internet.

SPOKEN COMMUNICATION

Important aspects of spoken (verbal) communication

include:

– clarity of speech and language used.

– tone of voice.

– ability to speak informatively.

Importance of communicating effectively

Laboratory staff must be able to communicate

well if a laboratory service is to function

smoothly and reliably and inspire user conﬁ-

dence.

In communicating it is important to consider:

● nature of the information being communi-

cated.

● person or persons to whom the information

is being communicated.

● most effective way of communicating the

information.

● whether the communicated information has

been understood and responded to appro-

priately.

Clarity of speech and language used

The main requirement of spoken communication is

that the words spoken can be heard distinctly by the

person to whom they are addressed in a language

and dialect that is clearly understood by the person.

A barrier to effective spoken communication is

background noise. Noise should therefore be kept

to a minimum when speaking, e.g. reduce the speed

of a centrifuge. Radios should not be played in lab-

oratories. Such noise not only interferes with com-

munication but can also be a distraction to persons

working in the laboratory leading to errors in work

due to loss of concentration.

It is particularly important to speak clearly and

politely when addressing patients. Hesitant and

mumbled instructions lead to misunderstandings

and a lack of conﬁdence by patients.

If the telephone is used to communicate test re-

sults, e.g. those needed urgently, it is particularly

important to speak clearly to avoid errors. The per-

son receiving the information should be asked to

repeat back the name and identiﬁcation number of

the patient, and the test result.

Tone of voice

A kind and understanding tone of voice may greatly

help a patient, especially a child, to feel less fright-

ened, whereas a loud and impatient tone of voice

may cause fear and add to the suffering of a patient.

A laboratory worker should always try to reassure

patients by explaining simply the procedure of a test

and, without disclosing professional information,

seek to answer patients’ queries. Try always to have

the time to listen.

It is particularly important to communicate well in

difﬁcult situations, for example when called to cross-

match blood during a night emergency. Under these

circumstances it is essential for the laboratory worker

not only to function rapidly and reliably but also to

reply calmly and patiently to anxious relatives and

blood donors.

Spoken communication is inﬂuenced by temp-

erament and fatigue, but a greeting and courteous

response based on local traditions and a respect for

all persons should always be possible.

Ability to speak informatively

The ability to speak competently and informatively is

particularly important when giving the results of

tests by telephone or directly to a medical ofﬁcer,

community health worker, or nurse. An understand-

ing of the clinical signiﬁcance of investigations is

required.

If a laboratory worker does not have sufﬁcient in-

formation to answer a question about a report, the

48 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

2.7

questioner should be referred to a more experi-

enced member of staff. If unable to reply and no

other person is available, the laboratory person must

advize that he or she is unable to assist. Inaccurate

information must never be communicated.

The ability to speak informatively is also required

when attending hospital interdepartmental meetings

to discuss laboratory policies. Always think through

what you are going to say before communicating it.

ACTION COMMUNICATION

Communication through a culturally acceptable

bodily manner and actions (body language) is par-

ticularly important when relating to patients.

A pleasant, friendly, professional manner and a

neat clean appearance inspire conﬁdence whereas

an impatient, aggressive manner or an untidy

appearance can make patients nervous and afraid.

When unable to speak the language of a patient,

facial expressions and actions become extremely im-

portant in reassuring a patient. In such a situation an

interpreter must be used to communicate important

information to a patient, obtain conﬁrmation of a

patient’s identity, and translate what the patient

wishes to say. A smile and a caring look and action

can inspire trust.

Appropriate action communication is also im-

portant among staff members if a pleasant working

environment is to be maintained.

REFERENCES

1 Nwobodo ED. Medical lab reports: Are we too conﬁdent

in their results? Africa Health, 2002, 3.

2 Bedu-Addo G, Bates I. Making the most of the labora-

tory. Principles of medicine in Africa, 2004, p. 1329.

Cambridge University Press.

3 Elsenga WK. Introduction of a quality assurance hand-

book, a guideline for accreditation of medical laboratories.

Paper presented at the 20th World congress of medical

technology, Dublin, 1992, July, pp. 26–31.

4 Houang L. Operating costs of the peripheral laboratory

and cost of tests. In health laboratories in developing coun-

tries. Proceedings of a Workshop, 1990. Health Co-

operation papers No. 10, Associazione Italiana ‘Amici di

R. Follereau’.

5 Mundy CJF et al. The operation, quality and costs of a

district hospital laboratory service in Malawi.

Transactions Royal Society Tropical Medicine and

Hygiene, 2003, 97, pp. 403–408.

6 WHO Essential Health Technologies (EHT)

Department. The role of laboratory external quality

assessment schemes, 2004. Accessed from the EHT

website www.who.int/eht/main_areas_of_work/DIL/

Lab_Tech(listed under Index as External Quality Ass….

11 Nov 2004).

Recommended Reading).

Safety equipment for district laboratories

This should include protective clothing for staff, ﬁre blanket,

dry chemical type ﬁre extinguisher, eye goggles, face visor,

face masks, eyewash bottle, chemical resistant gloves and

other types of protective gloves, First Aid box, devices to

avoid mouth-pipetting, waste and sharps disposal containers,

leakproof specimen containers, and an autoclave (or other

sterilizer), and when possible a biological safety cabinet.

DUTIES OF A LABORATORY SAFETY OFFICER

Although it is not possible to achieve absolute safety

in the laboratory, a Safety Ofﬁcer should be

appointed and work for the best possible level of

health and safety, promote safety awareness,

and make provision for continuing education in

biosafety.

A system for monitoring safety regulations in the

laboratory should be established. A check list should

be drawn up and regular (but random) inspections

made to:

 Ensure staff are practising their Safety Code and

know what to do if there is a ﬁre, equipment

fault, specimen or chemical spillage, or other ac-

cident in the laboratory.

 Make sure test methods are safe, specimens and

reagents are being handled and disposed of

safely and specimen containers are being decon-

taminated and cleaned correctly.

 Check that all hazardous chemicals and reagents

are marked with the correct hazard label and are

being stored and handled safely by staff.

 Make sure that there is no mouth-pipetting and

check protective gloves are being worn by staff.

 Observe whether protective clothing is being

worn and kept fastened and removed when

leaving the laboratory.

 Note whether other safety regulations are being

kept such as no smoking, eating, drinking, chew-

ing gum or applying cosmetics in the laboratory.

Laboratory fridges should be inspected for food

and drink.

 Check whether safety equipment such as the

First Aid box, eyewash bottles, eye goggles, sand

buckets, ﬁre blanket, and ﬁre extinguishers are in

good order and that staff know the locations and

how to use the equipment.

 Make sure corridors and exits from the labora-

tory are not being obstructed and ﬁre doors

(where ﬁtted) are being kept closed.

 Check whether the laboratory is being kept clean

and that benches are free of books, unnecessary

equipment, and personal property.

56 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

3.1–3.2

 Examine equipment for defects and observe

whether equipment is being used correctly and

maintenance checks are being performed.

Check also for cracked or chipped glassware.

 Observe whether safety regulations regarding

patients and visitors to the laboratory are being

followed and only authorised staff are entering

the working area.

 Check for any structural defects in the laboratory

or infestation by insects or rodents.

During such inspections, the safety ofﬁcer should

take the opportunity of reviewing and discussing

safety regulations with staff and revizing where

necessary FirstAid and ﬁre regulations.If a laboratory

accidenthas occurred recently, thecauses of it should

bediscusse dand if required, news afetymeasures in-

troducedto help prevent itsrecurrence. There should

follow a written report with recommendations.

Laboratory security should also be discussed.

It is the duty of the district safety ofﬁcer to in-

struct new members of staff (technical and auxillary)

in health and safety regulations. The Safety Ofﬁcer

must ensure that faults reported by staff concerning

safety are investigated promptly. Careful records

must be kept of all laboratory accidents.

3.2 Safe laboratory premise

and personal safety measures

Unsafe working premises and staff not following

personal health and safety measures are major

causes of accidents in district laboratories.

SAFE LABORATORYWORKING ENVIRONMENT

The safety of the working environment must take

into consideration:

– Type of work being performed, ie specimens

which the laboratory handles and pathogens

which may be encountered (mainly Risk Group

2 organisms, see subunit 3.3).

– Working practices including the procedures and

equipment used.

– Number of staff and workload.

– Laboratory’s location, climatic conditions, and

security of premise.

The following are important in making the work-

place safe:

 Laboratory premise that is structurally sound and

in good repair with a reliable water supply and a

safe plumbing and waste disposal system.

Drainage from sinks must be closed and con-

nected to a septic tank or to a deep pit.

Note: If there is a shortage of piped water, pro-

vision must be made for the storage of water,

e.g. collection of rain water in storage tanks. It is

not safe for a laboratory to function without an

adequate water supply.

 Adequate ﬂoor and bench space and storage

areas. The overall size of the laboratory must be

appropriate for the workload, staff numbers,

storage and equipment requirements.

 Well constructed ﬂoor with a surface that is non-

slip, impermeable to liquids, and resistant to

those chemicals used in the laboratory. It should

be bevelled to the wall and the entire ﬂoor

should be accessible for washing. The ﬂoor must

not be waxed or covered with matting. Floor

drains are recommended.

 Walls that are smooth, free from cracks, imper-

meable to liquids, and painted with washable

light coloured paint.

 When practical, a door at each end of the lab-

oratory so that laboratory staff will not be

trapped should a ﬁre break out. Doors should

open outwards and exit routes must never be

obstructed. Where ﬁtted, internal doors should

be self closing and contain upper viewing panes.

External doors must be ﬁtted with secure locks.

 Adequate ventilation supplied by wall vents and

windows that can be opened. The windows

should not face the prevailing winds to avoid

excessive dust entering the laboratory in the dry

season and the wind interfering with work activi-

ties. Windows should be ﬁtted with sun blinds

and insect proof screens, and when indicated

secure window bars.

 Sectioning of the laboratory into separate rooms

or working areas. The area where blood samples

are collected from patients must be away from

the testing area of the laboratory. Seating should

be provided for patients outside the laboratory.

The specimen reception area must be

equipped with a table or hatchway which has a

surface that is impervious, washable, and resis-

tant to disinfectants. There should also be a First

Aid area in the laboratory containing a First Aid

box, eyewash bottle and ﬁre blanket.

HEALTHANDSAFETYINDISTRICTLABORATORIES 57

3.2

Note: A layout of a typical district hospital lab-

oratory and other useful information on how to

improve district laboratory biosafety can be

found in the Essential Medical Laboratory

Services Project Report: Malawi, 2002.

 Bench surfaces that are without cracks, impervi-

ous, washable, and resistant to the disinfectants

and chemicals used in the laboratory.

Benches, shelving, and cupboards need to be

well constructed and kept free of insect and

rodent infestation. Benches should be kept as

clear as possible to provide maximum working

area and facilitate cleaning.

 Suitable storage facilities, including a ventilated

locked store for the storage of chemicals and

expensive equipment.

 Where required, a gas supply that is piped into

the laboratory with the gas cylinder stored in an

outside weatherproof, well-ventilated locked

store.

 A staff room that is separate from the working

area where refreshments can be taken and per-

sonal food and other belongings stored safely.

Wall pegs should be provided in the labora-

tory on which to hang protective clothing.

Near to the staff room there should be a

separate room with toilet and hand-washing

facilities. There should be separate toilet facilities

for patients.

 A handbasin with running water, preferably sited

near the door. Whenever possible, taps should

be operated by wrist levers or foot pedals. Bars

of soap should be provided, not soap dispensers.

Ideally paper towels should be used. If this is

not possible small cloth hand towels that are

laundered daily should be provided.

 Provision of protective safety cabinets and fume

cupboards as required and when feasible.

 Safe electricity supply with sufﬁcient wall electric

points to avoid the use of adaptors and extension

leads (power supplies to district laboratories are

covered in subunit 4.2).

 Fire extinguishers sited at accessible points.

These need to be of the dry chemical type.

Several buckets of sand and a ﬁre blanket are

also required.

 As good illumination as possible. Low energy

tube lights are recommended. Window screens

must be ﬁtted to protect from direct sunlight and

glare but these should not make the working

areas too dark.

 Provision of separate labelled containers for the

decontamination of infected material, discarding

of needles, syringes, lancets, glassware for clean-

ing, broken glass, and general laboratory waste.

A warning symbol such as a red triangle can be

used to mark containers in which infected

material is placed.

Use of safety signs and symbols

Displaying suitable safety signs and symbols is one

way of promoting safety awareness. Examples of

prohibition (do not) signs are shown in Fig. 3.1. They

can be easily prepared locally. Prohibition signs are

always crossed by a red line. No smoking signs

should be displayed in the laboratory and adjacent

patient waiting areas.

58 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

3.2

PERSONAL HEALTH AND SAFETY MEASURES

Personal health and safety measures include:

– practice of personal hygiene.

– wearing of protective clothing.

– protective inoculations and medical

examinations.

Practice of personal hygiene

Laboratory staff must practice a high standard of

personal hygiene. This includes:

 Washing hands and arms with soap and water

before attending outpatients, visiting wards, after

handling specimens and infected material, when

leaving the laboratory, and at the end of the

day’s work. When running water supplies are in-

terrupted, a tip type water container suspended

over the sink should be used for handwashing,

not a basin of water. Frequent handwashing is the

most effective action a laboratory worker can take

to avoid laboratory-acquired infection.

 Covering any cuts, insect bites, open sores, or

wounds on the hands or other exposed parts of

the body with a water-proof adhesive dressing.

Irritating Insect bites should be treated.

 Wearing closed shoes and not walking barefoot.

 Not eating, drinking, chewing gum, smoking, or

applying cosmetics in any part of the laboratory

and not sitting on laboratory benches.

Note: Food or drink should never be stored in a

laboratory refrigerator.

The international biohazard sign as shown in Fig.

3.2 should be displayed on the laboratory door. It

indicates that the laboratory handles samples that

contain pathogenic microorganisms and therefore

access is restricted to authorised persons.

Recommended signs for labelling chemicals and

reagents, e.g. Flammable, Toxic, Corrosive, Harmful,

Irritant, Oxidizing, and Explosive can be found in

subunit 3.5.

Fig. 3.1 Prohibition signs for wall display

Fig. 3.2 International Biohazard Symbol

 Not licking gummed labels or placing pens, pen-

cils or other articles near the mouth, eyes, or in

hair.

 Avoid wearing jewellery in the working area,

particularly pendant necklaces and bracelets.

Important: Staff should know what to do should a

laboratory accident occur. An appropriately

equipped First Aid box should be accessible (see

subunit 3.8).

Protective clothing

Protective overall

An overall (coverall) should be worn over normal

clothing or instead of it to protect the major part of

the body from splashes, droplets of liquids contain-

ing microorganisms, and hazardous chemicals.

When indicated a waterproof apron should also be

worn.

The protective overall should be made of a

fabric such as polycotton that can be bleached and

frequently laundered and is suitable for wearing in

tropical climates. Ideally the fabric should also be

antistatic and ﬂammable-resistant.

The overall must be worn with fasteners, buttons,

or tape closed. A side closing design with Velcrotype

tape is preferable to a front opening because it gives

better protection when working at the bench and

enables the overall to be removed quickly should

harmful or infectious material be spilt on it.

Soiled clothing should be placed in a special bag

and not left in a cupboard or under a bench in the

laboratory. Prior to laundering, the clothing and bag

should be soaked overnight in 1% v/v domestic

bleach. Protective clothing should always be left in

the laboratory working area and never taken home

or worn in a room where refreshments are taken.

When attending outpatients or inpatients, a clean

overall should be worn.

Gloves

Protective gloves should be worn when taking

samples from patients and when handling speci-

mens or cultures which may contain highly infec-

tious pathogens, e.g. Risk Group 3 organisms or

specimens from patients who may have hepatitis,

HIV infection or haemorrhagic fever. If indicated the

work should be undertaken in a biological safety

cabinet (see subunit 3.3).

Highly infectious material: This should be handled in a

laboratory with adequate containment facilities.

Re-usable gloves must be decontaminated and

washed while on the hands and after removal (see

subunit 3.4). Heat-resistant gloves should be worn

HEALTHANDSAFETYINDISTRICTLABORATORIES 59

3.2–3.3

when handling hot objects, e.g. when unloading

an autoclave. Chemical resistant gloves should be

worn when handling hazardous chemicals. Rubber

gloves should be worn when cleaning and washing

laboratory-ware.

Safety goggles, face shields, dust masks, respirators

Shatter-proof safety goggles or face shields (visors)

should be worn when necessary to protect the

eyes and face from splashes, e.g. when handling

hazardous chemicals including disinfectants. Safety

goggles should ﬁt over spectacles if worn and also

have sidepieces. Dust masks can protect against in-

haling particles of chemicals that are toxic or irritant.

Fabric masks provide only limited protection,

particularly against inhaling aerosols or chemical

particles. Personal respirators should be considered

to protect staff working with M tuberculosis.

Protective inoculations and medical

examinations

There should be a pre-employment health check

for all new members of staff. It is not possible or

desirable to vaccinate laboratory workers against

all the pathogens with which they may come in

contact. The medical ofﬁcer in charge of the

laboratory should decide which vaccinations are

required. Protective inoculations are usually

given against tuberculosis (when not Mantoux posi-

tive), typhoid, diphtheria, tetanus, poliomyelitis, and

cholera.

Note: In HIV high prevalence areas, laboratory staff

who know that they are HIV positive should be

aware of the risk of working with sputum samples

that may contain M. tuberculosis.

3.3 Microbial hazards

Preventing laboratory associated infections depends

on laboratory staff understanding:

 The routes by which infections are acquired in

the laboratory. These may be different from

‘natural’ infections.

 Which organisms are the most hazardous so that

time and labour are not wasted on unnecessary

precautions.

 Which techniques are the most hazardous so

that these may be replaced by those that are

safer.

 How the laboratory worker can reduce direct

contact with infectious material and use safe

working practices.

LABORATORYACQUIRED INFECTIONS

Infections may be caused by microorganisms enter-

ing the body through the:

– skin,

– eyes,

– mouth,

– respiratory tract.

Infection through the skin and eyes

Organisms can penetrate the skin through cuts and

scratches. They can b e picked up on the hands

from benches and equipment which have b een

accidentally contaminated by small, usually

unnoticed, drops, spills, and splashes. They may be

transferred to the face or eyes by the ﬁngers. Eye

infections can also occur by sample splashing to

the eye.

Infection through the mouth

Microorganisms may be ingested during mouth-

pipetting, either by direct aspiration or from the

mouth ends of pipettes which have been touched by

contaminated ﬁngers. Direct ﬁnger to mouth infec-

tion is also possible, as is infection by eating food in

the laboratory. Food may become contaminated

from benches or ﬁngers, or by contact with infected

material, for example in a refrigerator.

Organisms may also be transferred to the mouth

by cigarettes, cigars, or pipes which are handled or

placed on laboratory benches. For some pathogens

only a small number of organisms need to be in-

gested to cause infection, e.g. only a low infective

dose is required for Shigella infections.

Infection through the respiratory tract

Many common laboratory proce dures with micro-

organisms release aerosols, i.e. infecte d airborne

droplets, into the atmosphere. The larger of these

fall rapidly and contaminate hands, benches, and

equipment. Small droplets evaporate and leave

behind ‘droplet nuclei’ consisting of bacteria or

viruses which are too light to settle. They are

moved around a room and even a whole building

by small air currents and ventilation systems. If

inhaled, particles more than about 10 min

diameter, will be captured in the nasal passages.

Smaller particles, however, particularly those less

than 5 m in size, will not be trapped and may be

inhaled right into the lungs where they may start

an infection.

60 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

3.3

Infection of the general public

Microorganisms from laboratories may enter the

bodies of members of the general public by the

same routes as those affecting laboratory workers,

but the sources are different.

The general public may become infected as a

result of an ‘escape’ of microorganisms during the

transport of infectious specimens to or between lab-

oratories, for example from health centres to hospi-

tals. Another source of infection can occur if the

public comes into contact with infectious waste,

discarded or efﬂuent materials from the laboratory,

due to a failure of the laboratory to decontaminate

such materials.

CLASSIFICATION OF I NFECTIVE M ICROORGANISMS

Experience has conﬁrmed that some organisms are

more hazardous to handle and are more likely to in-

fect laboratory workers than others, e.g. hepatitis

viruses. More pathogens are also becoming resistant

to available antimicrobials, making the treatment of

infections caused by these resistant organisms more

difﬁcult.

The World Health Organization classiﬁes

infective microorganisms into four Risk Groups 1, 2,

3, and 4.

Agents in each Risk Group

The World Health Organization recommends that the health

authorities of each country should make lists of the organisms

and viruses in each Risk Group, relevant to their local cir-

cumstances so that appropriate precautions may be applied.

No one list will sufﬁce for all countries because circum-

stances will vary from one region to another. For example, if

an organism is widespread in a community, there is no point

in taking elaborate laboratory precautions to protect labora-

tory staff. Again, there will be little need to protect the

community if an infection is unlikely to spread because of the

absence of vectors or as a result of good sanitation or other

public health measures.

Risk Group 1

The organisms in this group present a low risk to the

individual laboratory worker and to members of the

community. They are unlikely to cause human or

animal disease.

Examples include food spoilage bacteria,

common moulds, and yeasts.

Risk Group 2

These organisms offer a moderate risk to the lab-

oratory worker and a limited risk to members of the

community. They can cause serious human disease

but are not a serious hazard. Effective preventive

measures and treatment are available and the risk of

spread in the community is limited.

Examples include staphylococci, streptococci,

enterobacteria (except Salmonella typhi), clostridia,

vibrios, adenoviruses, polioviruses, coxsackieviruses,

hepatitis viruses, Blastomyces, Toxoplasma, and

Leishmania.

Risk Group 3

This group contains organisms that present a high

risk to the laboratory worker but a low risk to the

community should they escape from the laboratory.

They do not ordinarily spread rapidly from one indi-

vidual to another. Again, there are effective vaccines

and therapeutic materials for most pathogens in this

group.

Examples include Brucella,Mycobacterium tuber-

culosis, Salmonella typhi, Francisella,Pasteurella pestis,

many arboviruses, LCM virus, rickettsiae, chlamydia,

Coccidioides, Histoplasma, human immunodeﬁciency

viruses (HIV).

Risk Group 4

The agents in this group offer a high risk to the

laboratory worker and to the community. They

can cause serious disease and are readily trans-

mitted from one individual to another. Effective

treatment and preventive measures are not usually

available.

Examples include viruses of haemorrhagic fevers

including Marburg, Lassa and Ebola, equine and

other encephalitis viruses, SARS virus, and certain

arboviruses.

Classiﬁcation of laboratories

Work with organisms in different Risk Groups requires dif-

ferent conditions for containment and different equipment

and procedures to conduct work safely. Assignment of an

agent to a biosafety level for laboratory work must be based

on a risk assessment.

There are four Biosafety Levels of laboratory:

 Basic, Biosafety Level 1

 Basic, Biosafety Level 2

 Containment, Biosafety Level 3

 Maximum Containment, Biosafety Level 4

Basic laboratory, Level 1: This is the simplest kind and is

adequate for work with organisms in Risk Group 1.

Basic laboratory, Level 2: This is suitable for work with or-

ganisms in Risk Group 2. It should be clean and provide

enough space for the workload and the staff, have adequate

sanitary facilities, especially for handwashing, and be

equipped with an autoclave. A biological safety cabinet is

desirable.

Containment laboratory, Level 3: This is more sophisticated

and is used for work with organisms in Risk Group 3 e.g.

HEALTHANDSAFETYINDISTRICTLABORATORIES 61

3.3

culture work. The principle is to remove from the Basic lab-

oratory those organisms and activities which are particularly

hazardous because they are the most likely to infect by the air-

borne route, ingestion, or injection of very small numbers.

The object is to expose as few people as possible to the risk of

infection.

The Containment laboratory is therefore a separate room

with controlled access by authorized staff only. It should be

ﬁtted with an appropriate biological safety cabinet. Its venti-

lation should be arranged so that air ﬂows into it from other

rooms or corridors and out to the atmosphere (e.g. through

the ﬁlters of the safety cabinet) and never in the reverse

direction. This will prevent infectious aerosols which might be

released in the Containment laboratory from escaping into

other areas.

Maximum Containment laboratory, Level 4:This is intended

for work with viruses in Risk Group 4, for which the most

strict safety precautions are necessary.

These laboratories are usually separate buildings with

strictly controlled access through air locks and exit through

decontaminant showers. They have pressure gradients

between their various rooms and all air from rooms and safety

cabinets is ﬁltered twice before discharge to the atmosphere.

All efﬂuents from sinks, lavatories, etc. are decontaminated

before discharge into the public sewer. The staff of these

laboratories are speciﬁcally trained for the work they do.

WORKING SAFELY

Good technique and the practice of personal

hygiene as described in subunit 3.2 are the most

important ways of reducing contact with infectious

material and preventing laboratory related

infections.

Special precautions need to be taken when col-

lecting and testing specimens and handling infected

material. Careless handling of specimens, cultures

and other infected material can result in the:

– contamination of ﬁngers,

– contamination of working surfaces and

equipment,

– formation of aerosols (airborne droplets).

Important: Inhaling infected aerosols is a common

cause of infection.

How aerosols are formed

The following are the main ways aerosols can be

formed in the laboratory:

 Pouring off supernatant ﬂuids, particularly from a

considerable height into a discard container.

 Vigorous tapping of a tube to resuspend a

sediment.

 Opening cultures and the rapid snap-closing of

specimen or culture containers.

 Heating a contaminated wire loop in an open

Bunsen burner ﬂame.

 Using a long springy loop which is not properly

closed.

 Rapid rinsing of Pasteur pipettes or plastic bulb

pipettes, particularly when a discard container is

almost full.

 Vigorous shaking of unstoppered tubes in a rack.

 Centrifuging specimens or infected ﬂuids in

open buckets, particularly when using a hand

operated centrifuge or an angled head cen-

trifuge and the tubes are more than three-

quarters full.

 Opening a centrifuge immediately following the

breakage of a tube or container of infected ﬂuid

before the aerosols have had time to settle.

 Dropping or spilling a specimen or culture.

 Mouth-pipetting and expelling an infected ﬂuid,

particularly blowing out the last drop.

Important: It is essential that all laboratory staff know

how to work safely to prevent the formation, disper-

sion, and inhalation of aerosols.

Pouring infectious material safely

When needing to pour infectious ﬂuids, for example

in disposing of supernatants that cannot easily

be pipetted, the ﬂuids should be poured carefully

down the side of a funnel (metal or plastic) with the

narrow end of the funnel submerged in disinfectant

in a jar or beaker. This prevents splashes and

aerosol dispersion. The lip of the tube should

then be wiped with absorbent paper soaked in

disinfectant.

Opening cultures and ampoules safely

If there is a ﬁlm of liquid between two surfaces that

are parted violently, an aerosol will be produced.

Such ﬁlms containing microorganisms frequently

occur between the rims and bottoms of petri

dishes, and the stoppers and rims of bottles and

tubes. There is no simple solution to this problem

apart from care to prevent the ﬁlms forming, and

where possible, opening the containers in a safety

cabinet.

Dried material in ampoules (stock cultures) may

also be dispersed if an ampoule is opened incor-

rectly. To open an ampoule safely, etch the glass

with a ﬁle above a cotton wool wad and then apply

a red hot wire to the etching so that the glass cracks

gently. After waiting a few minutes to allow air to

enter the tube and destroy the vacuum, the

ampoule should be held in a wad of cotton wool

and gently broken at the crack. Ampoules of Risk

62 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

3.3

Group 3 organisms should be opened in a safety

cabinet.

Inoculating loops and safe looping out

Long, springy, and improperly closed loops all shed

their loads easily, releasing aerosols which can be in-

haled and droplets which contaminate benches and

hands. When a hot loop touches a culture a sizzling

noise is heard. This indicates that aerosols are being

created.

Care, therefore, is needed in the making and use

of wire loops. The length of wire from the loop

holder to the loop should be short (6 cm), and the

loop itself should be small (2 mm in diameter) and

fully closed.

After ﬂaming, loops should be allowed to cool

before use. Whenever possible a hooded Bunsen

burner should be used (see Plate 3.1). Aerosols can

also be dispersed during the inoculation of culture

media especially when the surface of an agar plate is

rough because it contains air bubbles.

Shaking and homogenizing safely

It is often necessary to shake vigorously cultures and

materials containing microorganisms. Unless the

caps are very tight, small droplets may escape and

contaminate the surroundings. It is therefore good

practice to place even tightly capped bottles in

plastic bags before shaking.

Less violent mixing is frequently done by sucking

a ﬂuid up and down with a pipette (using a rubber

teat) but this usually releases aerosols. It is better to

use a Vortex mixer (see subunit 4.11). This does a

better job more safely.

Avoiding infection from centrifuge accidents

Most centrifuge accidents occur because the con-

tents on each side of a centrifuge are not balanced,

Plate 3.1 Hooded Bunsen burner. Information on suppliers

can be found in subunit 4.12

the buckets have been neglected and are corroded,

have not been placed correctly in the rotor, or the

centrifuge tubes are cracked or chipped (see also

subunit 4.7).

When tubes break in centrifuges, great clouds of

aerosols may be dispersed over wide areas. It is

usually obvious from the noise that a tube has

broken or a bucket has failed. The motor should be

switched off and the staff should leave the room for

30 minutes to allow most of the aerosols to settle or

to be removed by natural ventilation. An experi-

enced technician, wearing rubber gloves, should

then remove the buckets and debris for autoclaving

and swab out the bowl of the centrifuge with a

suitable disinfectant.

Even in the absence of accidents or misuse,

aerosols can be dispersed from uncapped cen-

trifuge tubes, especially when using a hand oper-

ated unprotected centrifuge. All tubes used for

centrifuging infectious material should be capped

and not ﬁlled more than three-quarters full. Sealed

centrifuge buckets should be used for Risk Group 3

material.

Avoiding infection from spillages and

breakages

Careless handling of pathological material and cul-

tures may result in the contamination of the outside

of vessels, the laboratory bench, or ﬂoor. Micro-

organisms can then be transferred from these

surfaces to the ﬁngers and hands, enter the blood-

stream through cuts and scratches, or be transferred

to the mouth and eyes.

Specimens, culture tubes and bottles should

always be placed in racks so that they cannot fall

over and spill their contents. When culture tubes or

bottles are broken, infectious aerosols may be

released. The worker should be careful not to

breathe the air in close proximity to the breakage

(this is difﬁcult, but there is no simple solution).

Spilled material and broken culture vessels

should be covered with a cloth soaked in disinfec-

tant, left for 30 minutes, and then cleared up using

a metal dust pan and stiff cardboard. These, and the

debris should then be autoclaved. Alternatively

disinfectant granules can be applied which are able

to disinfect the spillage in a shorter time (see subunit

3.4). Rubber gloves should be worn for the clearing

up operation.

Safe pipetting and dispensing

Mouth-pipetting has been the cause of many

infections, some of which have been fatal. Serious

injuries can also occur when mouth-pipetting

hazardous chemicals (see subunit 3.5).

HEALTHANDSAFETYINDISTRICTLABORATORIES 63

3.3

Acquiring infection by mouth-pipetting

This can occur when:

– pathogens in ﬂuid specimens and cultures are

accidentally sucked up into the mouth,

– aerosols are produced from the ﬂuid as it is

being sucked up or expelled,

– a pipette with an end that has been contami-

nated from ﬁngers or a bench surface, is put in

the mouth,

– a pipette with a chipped end causes cuts to the

ﬁngers or lips allowing pathogens to enter.

A cotton wool plug in the top of a pipette is not an

effective microbial ﬁlter. Using a pipette with

attached rubber tubing and mouthpiece is also

hazardous.

Safe use of syringes and needles

Care in the use of syringes and needles is needed

for several reasons. The obvious hazard is pricking

oneself or one’s colleague with a needle. This may

be avoided only by very careful handling. Needle-

pricks are a common source of laboratory acquired

hepatitis, particularly when the laboratory worker

tries to resheath a needle after use or leaves the

needle in a collection tray with used cotton wool

swabs and other articles instead of placing it in a

separate puncture proof container.

The decontamination, cleaning, and sterilization

of reusable syringes, and lancets are described in

subunit 3.4. Disposable needles and syringes

should be incinerated. Prior to incineration they

Prohibition of mouth-pipetting

Due to the high risk of infection and injury to

laboratory staff, the World Health Organization

recommends that mouth-pipetting be banned

from all medical laboratories.

There are many inexpensive ways to pipette

and dispense safely without mouth-pipetting.

These are described in subunit 4.6.

should be discarded into jars or metal cans, not into

cardboard boxes because the sharp ends may pen-

etrate the card and prick any person who handles

the box. The jars or cans should not be allowe d

to overﬁll.

Other hazards arise from aerosols, created if a

needle ﬂies off the end of a syringe when pressure

is applied to the plunger and the needle is blocked,

or when a needle is withdrawn through the rubber

cap of a vaccine-type bottle containing micro-

organisms. The second situation can be avoided by

withdrawing the needle through a swab of cotton

wool held over the vaccine bottle cap. This prevents

needle vibration and takes care of leakage.

BIOLOGICAL SAFETY CABINETS

Safety cabinets are intended to protect a laboratory

worker from aerosols and airborne particles. They

will not protect the person from spillages and the

consequences of mishandling and poor technique.

There are three kinds of safety cabinet, Classes I, II,

and III.

Class I and Class II cabinets are used in diagnos-

tic and containment laboratories for work with Risk

Group 3 organisms. Class III cabinets are used

almost exclusively for Risk Group 4 organisms.

Note: In district laboratories the resources for

purchasing a safety cabinet and the facilities for

installing, using, and maintaining such a cabinet may

not be available. It is therefore particularly important

for laboratory staff to follow safe working practices.

Class I safety cabinet

A Class I cabinet is shown in Fig. 3.3. It has a front

opening. The operator sits at the cabinet, looks

through the glass screen, and works with the hands

inside. Any aerosols released from cultures or other

infectious material are retained because a current of

air passes in at the front of the cabinet and sweeps

the aerosols up through a HEPA ﬁlter which

removes all or most of the organisms.

Clean air then passes through the fan, which

maintains the air ﬂow, and is exhausted (discharged)

to atmosphere where any particles or organisms that

have not been retained on the ﬁlter are so diluted

that they are no longer likely to cause infection if

inhaled.

Class II safety cabinet

A Class II cabinet is shown in Fig. 3.4.

In a Class II cabinet about 70% of the air is

64 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

3.3

recirculated through ﬁlters so that the working area

is bathed in clean (almost sterile) air. The air ﬂow

carries along any aerosols produced in the course of

the work and these are removed by the ﬁlters. Some

of the air (about 30%) is exhausted to atmosphere

and is replaced by a ‘curtain’ of room air which

Fig. 3.3 Example of a Class I saftey cabinet

Reproduced from Laboratory Acquired Infections with

permission of Butterworth and Co Publishers Ltd.

Fig. 3.4 Example of a Class II saftey cabinet

Reproduced from Laboratory Acquired Infections with

permission of Butterworth and Co Publishers Ltd.

enters at the working face. This prevents the

escape of any particles or aerosols released in the

cabinet.

Class III safety cabinet for Risk Group 4 viruses

This type of cabinet is totally enclosed and is tested under

pressure to ensure that no particles can leak from it into the

room. The operator works with gloves which form part of the

cabinet. Air enters through a ﬁlter and is exhausted to atmos-

phere through one or two more ﬁlters.

Use of safety cabinets

A safety cabinet should not be loaded with unnec-

essary equipment or it will not carry out its job

properly. Work should be done in the middle to rear

of the cabinet, not near the front. The operator

should avoid bringing the hands and arms out of the

cabinet while working.

After each set of manipulations and before with-

drawing the hands, the operator should wait for 2–3

minutes to allow any aerosols to be swept into the

ﬁlters. After ﬁnishing work in a safety cabinet, the

hands and arms may be contaminated and should

be washed immediately.

Siting and maintenance of a safety cabinet

The efﬁcient working of a safety cabinet depends on

its correct sitingand proper maintenance. The manu-

facturer’sinstruction manualmust be studiedc arefully.

Safety cabinets should be swabbed out with a

suitable disinfectant after use and regularly decon-

taminated with formaldehyde. Decontamination is

essential before the ﬁlters are changed.

Note: Further information about biological safety

cabinets, including speciﬁcations, their siting and use

can be found in the WHO Laboratory Biosafety

Manual.

SAFE TRANSPORT OF SPECIMENS

Safety measures are needed to ensure specimens

are transported safely and with care:

– from a ward or outpatient (OPD) clinic to the

laboratory.

– between laboratories, e.g. from an outreach lab-

oratory to the district hospital laboratory or

regional public health laboratory, or from a qual-

ity control reference laboratory to laboratories

participating in an EQA programme.

Important: All specimens must be collected in leak-

proof appropriate containers.

HEALTHANDSAFETYINDISTRICTLABORATORIES 65

3.3

Transporting specimens from wards or OPD

clinics

When hand-carrying, place the specimens upright in

racks in a closed container. The racks and carrying

container should be made of plastic so that they can

be easily disinfected and washed between use. The

request forms should be placed in a plastic bag that

can be sealed (grip type). During the hot season, an

insulated container should be used to transport the

specimens.

Transporting specimens between laboratories

Make sure the specimen container is tightly closed

and the cap is not leaking. Wrap each specimen in

sufﬁcient absorbent material to absorb it should the

container break. Place it individually or with others in

a carton or strong plastic bag. Make sure there is

sufﬁcient packing material around the specimens to

prevent them moving in the container or bag. If

sending glass slide preparations, use a plastic

reusable slide mailer.

Pack the container or bag of specimens with the

sealed plastic bag containing the request forms in a

suitable insulated container which will withstand

shock and weight pressure. Use sufﬁcient packing

material in the insulated container. Insert a freezer

pack(s) or ice cubes (in sealed plastic bags) around

the container of specimens. Label the outer con-

tainer ‘Biological specimens – Infectious substance’,

preferably using the biohazard symbol shown in Fig.

3.5. The words KEEP COOL should also be promi-

nently displayed on the container. Fix a clearly

written delivery address label to the outer container.

A smaller label should show the address of the send-

ing laboratory. Cover the labels with clear adhesive

tape.

Fig. 3.5 Infections substance label.

Important: Use hospital transport or other reliable

carrier to transport specimens.

Postal transport regulations

If using the postal system, laboratories must follow

their national postal regulations which apply to the

mailing of biological infectious substances. These will

be available from the postal service. The postal

system is appropriate for sending formol saline

preserved biopsies or ﬁxed smears to a

histopathological laboratory.

International transport regulations

Strict regulations exist for the transport of infectious

materials, including the proper use of packaging materials.

Major changes to the transport regulations were introduced in

2003.

Guidance can be obtained from WHO

and from the

International Air Transport Association (IATA).

3.4 Decontamination of

infectious material and

disposal of laboratory waste

It is essential for all district laboratories to operate

and sustain safe and effective systems for:

 Decontamination and disposal of specimens,

cultures and other material which may contain

infectious pathogens. All specimens should be

regarded as potentially infectious.

 Decontamination of glassware, plasticware, rub-

ber gloves, protective clothing, and equipment

used in laboratory testing.

 Cleaning of reusable items such as specimen

containers, other glassware and plasticware,

syringes, lancets, rubber gloves, etc.

 Sterilization of cleaned reusable items where

sterility is required before reuse.

Limitations in the use of disposables

Many district laboratory services in developing countries are

unable or cannot afford to obtain regular supplies of dispos-

able syringes, lancets, specimen containers, petri dishes, tubes,

pipettes, rubber gloves, etc. This subunit provides guidelines

on the decontamination, cleaning, and sterilization of

reusable items using methods that are feasible in district

laboratories.

66 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

3.3–3.4

METHODS OF DECONTAMINATION AND DIS POSAL OF

LABORATORYWASTE

In microbiological laboratory work, decontamination

means the making safe of infectious material or

articles that have been in contact with infectious

microorganisms prior to their disposal or cleaning

and reuse.

Safe processing of infectious laboratory waste

and contaminated articles requires the separation of

such waste and articles into clearly labelled (prefer-

ably colour-coded) discard containers according to

method of decontamination, disposal, and associ-

ated hazard.

Before being washed and reused, discarded, or

leaving the laboratory, all infectious material and

contaminated articles should be made non-

infectious.

Methods used to decontaminate infectious material

in district laboratories include:

 autoclaving (sterilization)

 boiling (effective method of disinfection)

 use of chemical disinfectants

Sterilization

This is the most reliable way of achieving decontamination

because it completely destroys microorganisms, including

bacterial spores.

Responsibility of the laboratory for safe

decontamination, recycling, and disposal

Laboratory staff have a responsibility to protect

themselves, patients, the community, and en-

vironment from injury or damage originating

from infectious or toxic laboratory waste and to

minimize the hazards involved in decontami-

nation, recycling, and disposal.

Risks can be minimized by laboratory staff:

● practising personal hygiene,

● following safe working practices,

● knowing and following correct methods for:

– separating infe ctious materials and

laboratory waste,

– de contaminating and disposing of

non-reusable infectious waste,

– making non-infe ctious, cleaning, and

sterilizing reusable articles.

Important: It is the responsibility of district

health authorities to provide the equipment

and supplies needed by district laboratories to

operate a safe programme of decontamination,

disposal, and recycling.

Disinfection

This aims to destroy or at least reduce the number of contam-

inating microorganisms to levels that are no longer regarded

as harmful to health. It implies the destruction of vegetative

(non-sporing) infectious microorganisms but not necessarily

bacterial spores.

Methods used to dispose of laboratory waste in

district laboratories include:

 incineration

 burial in a deep covered waste pit or landﬁll

Note: Chart 3.2 provides guidelines on how to de-

contaminate and dispose of laboratory waste and

make non-infectious those articles that need to be

cleaned and reused.

Autoclaving

A district hospital laboratory must have access to

a reliable autoclave for decontaminating cultures

and other infectious waste. Health centre labora-

tories should be supplied with a pressure cooker

type autoclave and the fuel to run it.

When performed correctly, autoclaving is the

most effective method of decontamination because

it is capable of sterilizing infectious waste, i.e. de-

stroying all bacteria, bacterial spores, viruses, fungi,

and protozoa. During autoclaving, pressure is used

to produce high temperature steam. A temperature

of 121°C and holding time of 15 minutes, timed

from when 121°C is achieved in the load, is used to

sterilize infectious waste.

Agents requiring higher temperatures and holding times

Some transmissible agents, e.g. prions that cause Creutzfeldt

Jacob disease (CJD), require autoclaving at 134°C for 18

minutes to be inactivated.

Important: Laboratory staff must know how to use an

autoclave correctly and be aware of the dangers of

its misuse. The operating principle of autoclaves,

their correct use and control are described in sub-

unit 4.8.

Boiling

Heating in boiling water at 100°C for 20 minutes at

altitudes below 600 metres (2000 feet) is sufﬁcient

to kill all non-sporing bacteria, some bacterial spores,

fungi, protozoa, and viruses including hepatitis virus-

es and HIV. Adding 20 g sodium carbonate to every

litre of water increases the effectiveness of the

disinfection.

Boiling at higher altitudes

Water boils at 100°C at sea level. The temperature of

boiling water is reduced by approximately 1°C for every

500 metres above sea level. A boiling time of 30 minutes

is therefore recommended when the altitude is greater than

600 metres.

HEALTHANDSAFETYINDISTRICTLABORATORIES 67

3.4

If an electric ‘sterilizer’ is not available or there is

no mains electricity, a large pan or other metal con-

tainer can be used and the water heated using a

charcoal stove, kerosene or gas ring burner (located

in a safe place outside the laboratory working area).

Choose the coolest time of the day to boil and use

an autoclave.

When autoclaving is not possible, reusable

syringes, lancets, specimen containers and other

contaminated glassware and plasticware can be de-

contaminated by boiling in water for 10–20 minutes

before being cleaned for reuse. When boiling, all the

items must be completely submerged in the water.

After cleaning and before reuse, syringes and

lancets can be disinfected by boiling at 100°C for 20

minutes if sterilization by autoclaving is not possible.

The articles must be allowed to dry before being

used to collect blood samples otherwise the water

will haemolyze the red cells making the specimen

unﬁt for testing.

Use of disinfectants

Chemical disinfectants are expensive, hazardous to

health, and when compared with autoclaving and

boiling, chemical disinfection is the least reliable and

controllable method for the treatment of laboratory

infectious waste. It must also be remembered that

no single disinfectant is likely to kill all micro-

organisms in any sample of infected waste. For

example, chlorine releasing disinfectants are highly

active against viruses but poorly active against

mycobacteria, whereas phenolic agents are effective

against mycobacteria but poorly active against

viruses.

The laboratory use of chemical disinfectants

should be restricted to discard containers on the

bench, disinfecting equipment, bench surfaces, and

ﬂoors, and the treatment of spillages.

Correct dilutions must be used and the dilutions

must not be kept beyond their useful life which,

according to the disinfectant, will vary from a few

hours to a week or more. When used in discard con-

tainers, disinfectant solutions must be renewed daily.

All disinfectants are to some extent inactivated by

protein (particularly hypochlorite solutions), plastics,

rubber, hard water, and detergents. Disinfectant sol-

utions must not be overloaded because there is a

limit to the amount of material which they can

disinfect effectively. The article to be disinfected

must be in contact with the disinfectant and not

protected by air bubbles, immersion oil, or ﬁlms of

grease.

When emptying discard containers of disposable

items, use a plastic strainer to collect the waste. If

containing glass, e.g. haematocrit tubes or other

sharp items, transfer the waste to puncture-resistant

containers for disposal.

Caution: Care must be taken when using disinfect-

ants, particularly when preparing dilutions.

Disinfectants are toxic and mostly corrosive and

irritant. Safety goggles, plastic apron, and chemical

resistant rubber gloves must be worn. When not in

use, discard containers should be covered using lids

that can be removed easily. The containers should

not be placed in direct sunlight.

The following are the most commonly used

chemical disinfectants in district laboratories:

 phenolics

 chlorine-releasing products

 peroxygen compounds

 alcohols

Note: None of these substances will kill or even

disable microorganisms unless they are properly

used and renewed regularly.

Weak disinfectants unsuitable for laboratory use

These include Dettol, chlorhexidine products such as

Hibitane, Hibisol, cetrimide compounds such as Cetevalon,

and hypochlorite solutions sold for treating baby feeding

bottles.

Phenolics

Examples of phenolics include Hycolin, Sudol,

Clearsol, Printol, and Stericol.These are active against

all non-sporing bacteria including mycobacteria.

They do not kill spores and are poorly active against

viruses. Phenolics are not markedly inactivated by

proteins. At an alkaline pH, their activity is reduced.

Phenolic disinfectants should be used at 2–5%

v/v concentration according to the manufacturers’

instructions for the ‘dirtiest conditions’. Dilutions

should not be kept for more than 24 hours. They

are useful for decontaminating material which may

contain mycobacteria. Phenolics are non-corrosive.

They are often used for wiping bench surfaces and

ﬂoors and when chlorine products cannot be used

because of their corrosiveness.

Chlorine-releasing disinfectants

These compounds contain chlorine and work by giv-

ing off free chlorine which is highly active against

Gram positive and Gram negative bacteria and

viruses including HIV and hepatitis B virus. Chlorine-

releasing products are used in discard containers

and for treating spillages of blood. Against

mycobacteria, chlorine products are less effective

than phenolics.

In an acid environment, chlorine release is

accelerated. Chlorine products are not thereforere c-

68 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

3.4

ommended for use in discard containers into which

urine supernatants are poured (phenolics are more

appropriate).Chlorine-releasing disinfectants include:

● Sodium hypochlorite solutions sold as bleach sol-

utions for domestic and laundering purposes,

e.g. Chloros, Domestos, Jik, Presept, eau de Javel

and other trade names. These solutions generally

contain 5% available chlorine (but always read

the label on the container as some ‘thin’ bleach

solutions contain less than 5%).

Sodium hypochlorite solutions are also sold

for commercial use (in dairying and other trades

for disinfecting equipment). They usually contain

10% available chlorine and a surfactant.

Instability of hypochlorite solutions

Liquid bleach has the disadvantage that in heat and strong

light it rapidly deteriorates and looses its chlorine content.

This can be a serious problem in tropical countries. To

overcome this, the use of a more stable chlorine-releasing

compound such as sodium dichloroisocyanurate

(NaDCC) is recommended (see following text).

● Calcium hypochlorite granules or tablets which

contain about 70% available chlorine.

● Sodium dichloroisocyanurate (NaDCC) available

as:

– a powder cont aining approximately 60%

available chlorine,

– granules, e.g. HA Z-TABgranules containing

57.2–57.8% chlorine (99% by weight

NaDCC),

– t ablets containing 1.5 g chlorine per tablet

(approx. 2.5 g NaDCC), usually in combi-

nation with an effervescent agent,

– t ablets containing 2.5 g chlorine per tablet

(approx. 4.6 g NaDCC), e.g. HAZ-TAB

tablets without an effervescent agent.

Stability and other advantages of using NaDCC

Compared with hypochlorite solutions, NaDCC products

are more stable (3–5 y shelf-life) even at high tempera-

tures as along as they are stored in a dry environment.

Solutions of NaDCC are less inactivated by protein than

hypochlorite solutions and also have greater microbicidal

capacity than equivalent bleach solutions.

When treating spillages, the contact time of NaDCC

granules with the spillage can be reduced to 2–3 minutes

compared to the 30–60 minutes required when using

bleach solutions.

NaDCC non-effervescent tablets are easier and safer

to use in the laboratory, lighter in weight and therefore

easier and cheaper to transport.

Note: Some effervescent NaDCC tablets are expensive.

Non-effervescent products such as HAZ-TABtablets and

granules made by Guest Medical Trading Ltd (see

Appendix II) are recommended. NaDCC is readily

soluble in water, no effervescent agent is required.

Use of chlorine-releasing disinfectants in the labora-

tory: The disinfectant power of all chlorine-releasing

compounds is expressed as parts per million (ppm)

or percentage of available chlorine (av Cl) according

to concentration level as follows:

1 000 ppm  0.1% (1 g/l)

2 500 ppm  0.25% (2.5 g/l)

5 000 ppm  0.5% (5 g/l)

10 000 ppm 1% (10 g/l)

Note:If expressed in chlorametric degrees (°chloram),

1°chloram is equivalent to approximately 0.3% av Cl.

Chlorine solutions must be prepared daily and pro-

tected from sunlight and excessive heat. They are

strong oxidizing agents, corrosive to metal and may

damage rubber. The amount of available chlorine

required in solutions depends on the amount of

organic matter present. The following solutions are

recommended for use in the laboratory:

1000 ppm (0.1%) av Cl: For routine disinfection of

working surfaces and decontamination of soiled

hands and gloves.

2500 ppm (0.25%) av. Cl: For discard containers

(use non-metal containers).

HEALTHANDSAFETYINDISTRICTLABORATORIES 69

3.4

5000 ppm (0.5%) av Cl: For use in emergency situ-

ations involving all haemorrhagic fever viruses.

10000 ppm (1%) av Cl: For treating spillages of

infectious material.

Note: Preparation of the commonly used 5% liquid

hypochlorites (bleach) and of NaDCC products is

given in Table 3.1.

Peroxygen compounds

An example is Virkon which when used at 1% w\v

concentrationhas a wide range of bactericidal, viruci-

dal and fungicidal activity. It has variable activity

against bacterial spores. A 3% w\v concentration is

recommended for Mycobacterium species. Neat

powder is used for spillages. Virkon has a built-in

colourindic atorand combines cleaning withdisinfe c-

tion.When dilutedit is non-irritantand haslow dermal

toxicity.It canb eused to cleancentrifuges providingit

iswashed off. Dilutions arestable for 7 days.It is how-

everexpensive when comparedto hypochlorite disin-

fectants. Virkonis available in bothpowder and tablet

formfrom Antec International (see Appendix11).

Perasafe: Antec International also manufactures Perasafe

which is a useful disinfectant for sterilizing instruments. It has

Table 3.1 Preparation of chlorine-releasing disinfectants commonly used in district laboratories

PRODUCT AVAILABLE CHLORINE REQUIRED

1 000 ppm 2 500 ppm 10 000 ppm

Use: Benches, hands, gloves Discard jars Spillages

Sodium hypochlorite

5% solution (bleach) 20 ml in 50 ml in 200 ml in

1 litre water 1 litre water 1 litre water

10% solution 10 ml in 25 ml in 100 ml in

1 litre water 1 litre water 1 litre water

NaDCC tablets

1.5 g tablet 1 tablet 1 –2 tablets 2 tablets

in 1 litre in 1 litre in 250 ml

water water water

2.5 g tablet (HAZ-TAB) 1 tablet 1 tablet 1 tablet

in 2.5 litre in 1 litre in 250 ml

water water water

Note: In small laboratories it may be more convenient to dilute a 2500 ppm solution to obt ain a 1000 ppm

solution to disinfect working surfaces: i.e. use 40 ml of 2500 ppm and 60 ml of water to give 100 ml of a

1 000 ppm solution.

Use of HAZ-TAB NaDCC granules for spillages

While 10000 ppm NaDCC solution can be obtained from tablets, the use of HAZ-TAB granules is recommended because these

can be applied direct to the spillage, do not spread the spillage, and have a more rapid action (2–3 minutes).



a rapid action (10 minutes immersion) and does not have the

irritant and other health problems associated with the use of

glutaraldehyde.

Alcohols

Ethanol and propanol at 70–80% v/v concentration

in water are useful for disinfecting skin and surfaces.

Penetration of organic matter is poor. Alcohols are

highly active against mycobacteria, non-sporing

Gram positive and Gram negative bacteria, and

fungi. HIV and hepatitis B and C viruses are inacti-

vated. Activity against non-lipid (naked) viruses and

bacterial spores is poor. When mixed with hypochlo-

rite their activity is increased.

Aldehydes

These less used disinfectants include:

 Formaldehyde

 Glutaraldehyde (glutaral)

Formaldehyde gas is an effective disinfectant against all

microorganisms including viruses, except at temperatures

below 20°C. A 5% v/v formalin solution (diluted from con-

centrated formalin solution) is occasionally used as a disinfec-

tant but formalin is too irritant for general use as a laboratory

disinfectant. When heated, formaldehyde gas is used to de-

contaminate safety cabinets. It is non-corrosive. Formalin sol-

ution is toxic with an irritating vapour, and may cause

sensitivity reactions. It is also a suspected carcinogen. Use

only in a well ventilated laboratory.

Glutaraldehyde preparations include Cidex, Clinicide,

Glutarex 3M, Asep, Totacideand Triocide, usually supplied at

working concentrations of 2%. It is an expensive disinfectant.

An alkaline activator must be added which is usually supplied

with the product.

In the laboratory, glutaraldehyde is used mainly to disin-

fect metal surfaces, e.g. instruments and centrifuge parts

where corrosive chlorine products cannot be used and viral

contamination is possible. It rapidly inactivates bacteria and

viruses including HIV and hepatitis B virus. It is also active

against mycobacteria, but its penetration of organic matter is

poor. Most glutaraldehyde products remain active for 7–14

days after activation. Cloudy solutions however should be dis-

carded. Glutaraldehyde is toxic, irritant, and mutagenic.

Contact with skin, eyes, and respiratory tract should be

avoided.

Incineration

In district laboratories, incineration, i.e. destruction

by burning, is a practical and effective method of

disposing of laboratory waste including contami-

nated disposables and specimens in non-reusable

containers, e.g. faeces. Purpose-built incinerators are

rarely available at district level. Open burning is

more common. The materials to be incinerated must

be carried to the incineration site in closed leak-

proof puncture resistant containers.

Local construction of a simple incinerator

– Use an empty 300 litre (40 gallon) petrol drum

and obtain a metal lid and piece of ﬁne wire

70 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

3.4

mesh (to replace the lid when burning is in

progress).

– Fix a strong metal grating about a third of the

way up the drum, inserting steel rods to keep it

in place.

– Cut a wide opening below the level of the

grating as shown in Fig. 3.6.

Use the incinerator as follows:

1 Place the material for incineration on the grating

of the incinerator on top of a waste sheet of

paper or cardboard (to prevent items falling

through the grating). Do not overﬁll. Replace the

lid.

2 Fill the bottom of the drum with sticks, wood

shavings, and other combustible material.

3 Remove the lid and replace with the ﬁne wire

mesh to retain burning fragments and smuts.

4 Light the ﬁre and keep it burning until all the

waste has been burnt.

5 When cool, bury the ash in a deep covered pit.

Do not empty it on open waste ground.

Important: Site the incinerator in a safe place.

Surround it with a wire fence to prevent entry of

unauthorized persons or animals. Supervize the

incineration and bury the ash as soon as it has

cooled sufﬁciently (wear a dust mask and protective

gloves).

Brick built incinerator: A simple to construct brick incinera-

tor is described in Practical Laboratory Manual for health

centres in eastern Africa.

Steel rods to

support grid

Vent

Fig. 3.6 Simple ﬁeld incinerator

Courtesy of the World Health Organization

Burial in a deep pit or landﬁll

Burying lab oratory waste prevents it becoming a

hazard providing the pit is located in a safe fenced

off area, is sufﬁciently deep (4–5 metres) and wide

(1–2 metres), has a strengthened rim, and is kept

covered. The disposal pit should not be used for

items that do not decompose, e.g. plastic lab-

oratoryware. These are best incinerated. Ideally all

infectious laboratory waste should b e decont ami-

nated or incinerated before it is discarded in a pit

or landﬁll. Once a week the waste should be

covered by a layer of quicklime, or if unavailable by

soil or leaves.

If a local landﬁll site is available, local health

authority guidelines should be followed regarding

its use. (Laboratory waste must never be dis-

posed of with household waste.) Waste must

always be transported in closed, strong, leakproof

containers.

Note: Chart 3.2 summarizes the methods used to

decontaminate and dispose of non-reusable

infectious material and how to decontaminate and

clean reusable articles in district laboratories.

CLEANING AND STERILIZATION OF R EUSABLE ITEMS

Decontamination is essential prior to the cleaning

and reuse of laboratory-ware. In district laboratories,

almost all glassware, many plastic items, and speci-

HEALTHANDSAFETYINDISTRICTLABORATORIES 71

3.4

men containers will need to be reused. Disposable

containers should be used for faecal specimens.

Separate discard containers (preferably plastic),

ﬁlled with appropriate disinfectant are required for

syringes, lancets, slides, cover glasses, pipettes, tubes

and specimen containers. Each container should be

clearly labelled.

Prior to soaking slides in disinfectant, any oil

should be removed using a piece of rag or

absorbent paper dampened with disinfectant. Use

forceps to wipe the slide and dispose of the rag

or tissue.

Most locally available detergents are suitable for

cleaning laboratory-ware. After cleaning, each article

must be well rinsed in clean water to remove all

traces of detergent.

Caution: Great care must be taken to avoid injury

when handling lancets, scalpel blades, and cover-

glasses. When cleaning cover glasses (No 2 thick-

ness are suitable for reuse), lancets, and scalpel

blades, use small plastic beakers or jars in which to

wash and rinse these items and plastic strainers

to collect them after washing and between water

rinses to avoid pricks and cuts. Always wear protec-

tive gloves when cleaning laboratory-ware.

Sterilization of cleaned laboratory-ware prior to

reuse is necessary for microbiology culture work,

e.g. specimen containers, petri dishes, tubes,

pipettes, etc. Syringes and lancets must also be

sterilized before reuse (see subunit 4.8).

Chart 3.2 Processing of infectious and waste material and reuse of non-disposable items in district

laboratories

SPECIMENS Fluid specimens

In reusable containers: If the sink has running water and empties into the sewer system or septic tank, pour

ﬂuid specimens through a plastic funnel down the sink and rinse the funnel and sink

with 2500 ppm chlorine or 5% v/v phenolic disinfectant. Boil the containers, c aps

and cap liners for 10 minutes at 100°C. If this is not possible, immerse the con-

tainers, caps, and liners overnight in 5% v/v phenolic disinfectant, 2 500 ppm

chlorine disinfectant or 1% w/v Virkon.

Clean each container in detergent, rinse well in water and drain dry. If sterile

containers are required, autoclave them at 121°C for 15 minutes.

Urine and other supernatant ﬂuids

Discard supernatant ﬂuids through a funnel held in the lid of a plastic 1 litre capacity

container to which has been added 20 ml of a concentrated phenolic disinfectant.

When the ﬂuid level reaches 1 litre, empty the container (do not add supernatant

ﬂuids to previously diluted disinfectant solutions). Decontaminate the empty tubes

or bottles and clean them as described previously for ﬂuid specimens.

72 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

3.4

Faeces

Use disposable containers for faeces. Dispose of the specimens by incineration.

Sputum

If not liquiﬁed, decontaminate sputum by autoclaving at 121°C for 15 minutes or

place the container in boiling water and boil at 100°C for 20 minutes. Discard the

decontaminated specimen in the latrine or in a deep covered pit and clean the

container. If liquiﬁed, use the procedure for ﬂuid specimens.

In disposable containers: Dispose of the specimens by incineration.

HAEMATOCRIT TUBES Immediately after reading, discard the tubes into a puncture resistant container for

incineration or burial in a deep covered pit.

Note: If a capillary tube is found to have broken in the centrifuge, wearing gloves

and using forceps, remove the broken glass pieces and clean the centrifuge with a

rag soaked in 5% v/v phenolic disinfectant. Place the rag with the pieces of glass in

a puncture resistant container for incineration.

SWABS Immerse swabs in 5% v/v phenolic disinfectant overnight before disposing of them

in a deep pit.

CULTURES Prior to disposal, de contaminate all cultures by autoclaving them at 121°C for 15

minutes.

MICROSCOPE SLIDES Soak used slides overnight or for at least 1 hour in 2500 ppm chlorine disinfe ctant

or 1% w/v Virkon (detergent as well as disinfectant) in a plastic container. If there is

oil on a slide, use forceps and a piece of rag or tissue soaked in disinfectant to wipe

off the oil before soaking the slide. With care, wash the slides in detergent using a

soft brush. Rinse well in water and dry between cotton cloths. When completely dry,

store the slides in boxes.

COVER GLASSES Only No 2 thickness cover glasses should be reused (No 1 cover glasses are too

Reuse only fragile). Using a piece of stick, transfer a cover glass from a slide to a small plastic jar

when essential or b eaker containing 5% v/v phenolic disinfectant or 1% w/v Virkon. Soak overnight or

for at least 1 hour.

Use a plastic sieve to collect the contents of the jar or beaker. Transfer a few cover

glasses at a time to a container of detergent (not necessary if Virkon has been used),

and swirl gently. Pour off the detergent and run water on the cover glasses to wash

off the detergent. Use a plastic sieve to recover the cover glasses and dry them

between two pieces of cotton cloth. Discard any damaged cover glasses into a

puncture resistant container.

PIPETTES Immediately after use, soak pipettes for at least 1 hour in 2500 ppm chlorine

disinfectant or 1% w/v Virkon in a sufﬁciently tall container to allow complete

immersion of each pipette and the expelling of air bubbles. Do not overcrowd the

container.

Caution: Use a separate container for glass Pasteur pipettes as the stems of these can be easily

broken.

Wash reusable pipettes in detergent (not necessary if Virkon has been used), rinse

well in water, and drain dry. Use a rubber bulb to expel the water from each pipette.

Bury disposable pipettes in a deep covered pit.

HEALTHANDSAFETYINDISTRICTLABORATORIES 73

3.4

LANCETS Immediately after use, immerse the lancets in a small plastic jar or beaker containing

Reuse only 1000 ppm chlorine or 1% w/v Virkon. Soak for 20 minutes. Use a plastic sieve to

when essential re cover the lancets from the container. Clean as described for cover glasses. Lancets

must be sterilized before reuse.

Autoclaving stainless steel lancets

Wrap each lancet in a small piece of non-shiny paper (can be reused). Place the

wrapped lancets in a small polypropylene or metal container and with lid removed,

sterilize at 121°C for 15 minutes. Replace the lid.

Boiling lancets

If unable to sterilize by autoclaving or because the lancets are part plastic, boil in

water at 100°C for 10 minutes together with small glass or polypropylene tubes into

which the lancets can be placed after boiling. Use ﬂame sterilized forceps

to transfer each lancet to its tube. Plug each tube with non-absorbent cotton wool.

SYRINGES Immediately after use, rinse through with 1000 ppm chlorine disinfectant. Remove

Reusable glass, nylon, the plunger from the barrel and immerse plunger and barrel in a container of

polypropylene syringes 1 000 ppm chlorine disinfectant or 1% w/v Virkon for 1 hour. Wash and rinse well

in several changes of water. The syringes must be sterilized before reuse.

Autoclaving syringes

Wrap each syringe, barrel alongside plunger, in a piece of cotton cloth or non-shiny

paper and autoclave at 121°C for 15 minutes.

Boiling syringes

If autoclaving is not possible, boil the syringes in water at 100°C for 10 minutes with

a container in which to place the syringes after boiling. Use ﬂame sterilized forceps

to remove and assemble the syringes. Use the syringes only when they are

completely dry.

TUBES Immerse overnight or for at least 1 hour in a container of 2500 ppm chlorine

disinfectant or 1% w/v Virkon. Make sure each tube is fully immersed with air

bubbles expelled. Do not overload the container.

Wash in detergent (not necessary if Virkon has been used) using a test tube brush,

rinse well in water and dry tubes facing downwards.

If sterile tubes are required, autoclave at 121°C for 15 minutes, with caps loosened.

Only glass or polypropylene tubes or vials can be autoclaved. If unable to autoclave,

boil the tubes with caps and cap liners in water at 100°C for 10 minutes. Use ﬂame

sterilized forceps to remove and cap the tubes when dry.

OTHER GLASSWARE As for tubes.

PLASTICWARE

DISPOSABLE WASTE

Syringes

Incinerate and bury the waste in a deep covered pit.

Contaminated cotton wool, Disc ard into a separate container and cover with a lid. Incinerate and bury the waste

swabs, dressings in a deep covered pit.

Reuse only

when essential

74 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

3.4

Broken glass, Discard into a puncture resistant container. Incinerate and bury the waste in a deep

disposable needles, covered pit.

lancets, other ‘sharps’

CLEANING OVERALLS Prior to laundering, decontaminate laboratory protective clothing and other

contaminated clothing by soaking overnight in 1000 ppm chlorine disinfect ant.

REUSING GLOVES Rinse gloved hands thoroughly in 1 000 ppm chlorine disinfectant followed by

several rinses in clean water (do not soak the gloves in disinfectant). Wash gloved

hands with soap and water. Remove the gloves and hang them by the cuffs to dry.

Wash hands and arms thoroughly.

When dry, examine the gloves for damage. Discard any gloves that are peeling,

appear cracked, have punctures or tears, or appear damaged in any other way. Test

the gloves for small holes by ﬁlling them with water and squeezing. If intact, turn the

gloves inside out to dry. When dry sprinkle the inside with talcum powder.

DECONTAMINATING Use 2500 ppm chlorine disinfectant to decontaminate work surfaces at the end of

BENCH SURFACES each day. Use 5% phenol disinfectant or phenol solution on benches which may be

contaminated with mycobacteria.

Spillages

Soak up any spillage of infectious material with Virkon powder disinfectant, NaDCC

granules or if unavailable use rags soaked in 10000 ppm chlorine. Always wear

protective gloves.

STERILIZING WIRE Decontaminate and sterilize by ﬂaming until red hot. Allow to cool before use.

LOOPS BLADES, ENDS Whenever possible, use a hooded Bunsen burner.

OF FORCEPS

Notes

● See Table 3.1 for the preparation of 1000 ppm, 2500 ppm and 10000 ppm chlorine solutions. Wear

gloves and a face visor or goggles when preparing all disinfectant solutions.

● When clean running water is not available for rinsing washed laboratoryware, use ﬁltered rain water.

● Always wear protective gloves and a plastic apron when decontaminating and disposing of specimens.

When disposing of waste from an incinerator, wear a dust mask.

3.5 Chemical and reagent

hazards

Hazards associated with the transport, storage, and

handling of chemicals include ﬁre, explosion and the

effects from toxic (poisonous), harmful, irritating,

and corrosive chemicals. In district laboratories the

risks associated with the use of chemicals can be

minimized by laboratory staff knowing which chem-

icals are hazardous and how to handle and store

them correctly.

In tropical countries it is particularly important to

keep chemicals and reagents out of direct sunlight

and prevent their overheating in the laboratory or in

an outside store. Overheating can decompose many

chemicals, causing explosions, ﬁre, or the formation

of toxic fumes.

Accurate records must be kept of all chemicals in

the laboratory. Chemicals and reagents must be

labelled clearly. In outreach laboratories those chem-

icals and reagents that are not required or are not

labelled must be sent to the nearest district hospital

laboratory for safe storage or disposal. The district

laboratory coordinator should supervize the packing

and transportation of these chemicals and reagents.

Most manufacturers of chemicals provide com-

prehensive hazard and safety information with their

products. Before storing or using a chemical, labora-

tory staff must read carefully the safety (S) and risk

(R) phrases written on the label of the container and

understand the hazard symbols used by manufac-

turers to identify chemicals that are:

HEALTHANDSAFETYINDISTRICTLABORATORIES 75

3.5

Hazard identiﬁcation and classiﬁcation schemes

The symbols and hazard classiﬁcation described above are

those used by manufacturers and users of chemicals in

European Community (EC) countries. Other countries ident-

ify and classify chemical hazards differently, e.g. according to

type including health, ﬁre, instability, reactivity hazards, and

the degree of danger using a scale 0 to 4 where 4 extreme,

3  severe, 2  moderate, 1  minor and 0  no unusual

hazard.

FLAMMABLE CHEM ICALS

A ﬂammable substance is one that readily ignites

(catches alight) and burns. Some ﬂammable chemi-

cals are a more serious ﬁre risk than others because

they ignite easily. Such chemicals have what is called

a low ﬂash point temperature.

Flash point of a chemical: This is the lowest temperature at

which the vapour above a liquid can be ignited in air. The

lower a chemical’s ﬂash point, the higher is the risk of an igni-

tion source igniting it. The most hazardous ﬂammable chemi-

cals are those with ﬂash points below ambient temperature

because they evaporate rapidly from open containers. See

also Chart 3.3 in subunit 3.7.

Classiﬁcation of ﬂammable chemicals

The term ﬂammable has the same meaning as

inﬂammable (ﬂammable is preferred).

Extremely ﬂammable: Liquids with a ﬂash point

below 0°C and a boiling point of 35°C or below, e.g.

acetone, diethyl ether.

Highly ﬂammable: Liquids with a ﬂash point below

21°C, substances which are spontaneously com-

bustible in air at ambient temperature, solids which

readily ignite after brief contact with ﬂame or which

evolve highly ﬂammable gases in contact with water

or moist air. Examples include absolute ethanol and

methanol, 70% and above ethanol and methanol,

methylated spirit, isopropanol (isopropyl alcohol),

toluene, alcoholic Romanowsky stains, acid alcohol,

other alcoholic reagents and indicators.

Flammable: Liquids with a ﬂash point of 21°C or

more and below or equal to 55°C, e.g. glacial acetic

acid, acetic anhydride, xylene.

Safe storage and use of ﬂammable chemicals

Storage

Keep only small quantities of ﬂammable chemicals

and reagents on laboratory benches and shelves

(not over 500 ml amounts). Store stock supplies of

ﬂammable chemicals particularly those that are ex-

tremely or highly ﬂammable in a closed steel or thick

plywood box at ground level, preferably in an out-

side locked store that is cool and well ventilated,













Flammable

(extremely

and highly)

Oxidizing

Toxic

Harmful

Irritating

Corrosive

Explosive

Dangerous for

environment

including ventilation at or near ﬂoor level because

the vapours of most highly ﬂammable liquids are

heavier than air. Label the container Flammable. Do

not store ﬂammable and oxidizing chemicals

together.

Safe use

 Keep the laboratory well ventilated to prevent

any build up of ﬂammable gases and vapours.

 Before opening a bottle containing a ﬂammable

liquid, always make sure there is no open ﬂame

within 2 metres such as that from a Bunsen

burner, spirit lamp, kerosene or gas burner.

When using ether or acetone allow a distance of

3 metres.

 Ensure stock bottles and dispensing containers of

ﬂammable liquids are tightly closed after use.

 Do not light a match or use a lighted taper near

to a ﬂammable chemical.

 Do not store ether in a non-spark refrigerator.

 Make sure no one smokes in or adjacent to the

laboratory. Display ‘no smoking’ notices.

 Place dispensing containers of acetone, acid alco-

hol, methanol, and alcoholic Romanowsky stains

well away from the rack used to heat stain on

slides in the Ziehl Neelsen technique. Use trays

to hold the containers to prevent a ﬂammable

liquid spreading should a spillage occur.

 If needing to heat a ﬂammable liquid, use a

waterbath. Never heat directly on a hotplate or

over an open ﬂame. Do not ﬂame the neck of a

bottle or tube containing a ﬂammable substance.

 When transporting Winchester bottles containing

ﬂammable chemicals, use strong carriers ﬁtted

with handles.

Control of ﬁres involving ﬂammable liquids

Fire caused by a ﬂammable liquid is best controlled

by smothering the ﬂames. If the ﬁre is a small one

on a bench, cover the container or area with a lid or

a ﬁre blanket (see 3.7). If the ﬁre is on the ﬂoor, use

a dry powder chemical ﬁre extinguisher or smother

the ﬂames with a ﬁre blanket, dry sand or earth.

Do not pour water on the ﬂames of a ﬂammable

liquid ﬁre because the water will spread the ﬁre,

especially if it is caused by a solvent such as xylene

which does not mix but ﬂoats on the surface of

water.

Note: Further information on the ﬁre risks associated

with the use of ﬂammable liquids can be found in

subunit 3.7 Fire safety.

76 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

3.5

OXIDIZING CHEMICALS

An oxidizing substance is one that produces heat or

evolves oxygen in contact with other substances

causing them to burn strongly or become explosive

or spontaneously combustible. Once a ﬁre is started

the oxidizing substance promotes it and impedes

ﬁre-ﬁghting.

Oxidizing chemicals include hydrogen peroxide and

other strong peroxides, nitric acid, ammonium ni-

trate, sodium nitrite, perchloric acid, sodium chlorate,

chromic acid, potassium dichromate, calcium

hypochlorite bleach powder, and potassium per-

manganate.

Safe storage and use of oxidizing chemicals

Storage

Because oxidizing chemicals can produce much

heat when in contact with ﬂammable substances,

organic materials and reducing agents, they must be

stored well away from such chemicals and other

chemicals with which they can react dangerously as

indicated in subunit 3.5.

Safe use

Always handle oxidizing chemicals with care.

Besides being ﬁre-promoting, most oxidizing sub-

stances are dangerous to skin and eyes.

TOXIC, HARMFUL AND IRRITATINGCHEMICALS

A toxicsubst ance is one that can cause serious acute

or chronic effects, even death, when inhaled, swal-

lowed, or absorbed through the skin. The term very,

or highly, toxic is used if the substance is capable of

causing serious effects.

Toxic chemicals include potassium cyanide,

mercury (e.g. from broken thermometers), mercury

11 (mercuric) nitrate, sodium azide, sodium nitro-

prusside, thiosemicarbazide, formaldehyde solution,

chloroform, barium chloride, diphenylamine, and

methanol.

A harmful substance is one that can cause limited

effects on health if inhaled, swallowed, or absorbed

through the skin.

Harmful chemicals include barium chloride,

benzoic acid, potassium oxalate, saponin, xylene,

iodine, and sulphanilic acid.

An irritating chemical is one that c an cause inﬂam-

mation and irritation of the skin, mucous mem-

branes, and respiratory tract following immediate,

prolonged or frequent contact.

Irritants include ammonia solution, acetic acid,

sulphosalicylic acid, potassium dichromate, and

formaldehyde vapour.

Safe storage and use of toxic, harmful and

irritating chemicals

Storage

Highly toxic chemicals such as potassium cyanide

must be kept in a locked cupboard. Stock solutions

or solids of harmful and irritating chemicals should

be stored safely in a cupboard, not on an open shelf.

Safe use

 Handle toxic, harmful, and irritating chemicals

with great care and wash the hands immediately

after use. Wear suitable protective gloves, and if

indicated a face dust mask, visor or eyeshields,

and a plastic protective apron.

 Ensure an eyewash bottle is accessible to rinse

the eyes should a toxic, harmful or irritating

chemical enter the eye (see Plate 3.2).

 Always lock away highly toxic chemicals im-

mediately after use and never leave such chemi-

cals unattended. Minimize exposure to highly

toxic chemicals.

HEALTHANDSAFETYINDISTRICTLABORATORIES 77

3.5

 Whenever possible, handle chemicals with an

irritating or harmful vapour in a fume cupboard.

If this is not possible, ensure the laboratory is well

ventilated while the chemical is being used.

 Before opening a chemical with an irritating

vapour, place a cloth over the neck of the con-

tainer and cap.

 Keep containers tightly closed.

 Never mouth-pipette any chemical or reagent.

Always use a pipette ﬁller, automatic dispenser or

pipettor.

Injuries caused by mouth-pipetting chemicals

and reagents

The following are the main ways a person can be

injured by mouth-pipetting chemicals and reagents.

– accidentally sucking up reagents into the mouth,

e.g. when rapidly sucking up in a narrow bore

pipette or when a reagent is contained in a

brown bottle or opaque plastic container and the

level of ﬂuid is low and cannot be seen clearly.

– putting a pipette in the mouth after its end has

been in contact with a harmful reagent, disinfec-

tant, or dry chemical picked up from the bench

or carried on the ﬁngers.

– inhaling poisonous or irritating fumes, e.g. from

acetic acid, concentrated hydrochloric acid, or

formalin solution.

Accidents involving toxic, harmful, and

irritating chemicals

The First Aid treatment for poisoning and injuries

caused by toxic, harmful and irritating chemicals is

described in subunit 3.8.

Allergenic, carcinogenic, mutagenic and teratogenic

substances

Some toxic chemicals are known to cause or are suspected of

causing speciﬁc types of disease or of affecting particular

organs or functions of the body as follows:

Allergen: Causes in some people allergic or hypersensitivity

reactions, e.g. skin contact resulting in dermatitis and inhala-

tion resulting in asthma or related conditions.

Carcinogen: Causes or increases the risk of cancer usually

after repeated or long term exposure. Chemicals with proven

carcinogenic properties include benzidine, o-tolidine,

o-toluidine, o-dianisidine, alpha- and beta-naphthylamine,

nitrosophenols, nitronaphthalenes, and selenite.

Mutagen:Capable of producing mutations of germ cells lead-

ing to genetically induced malformations, spontaneous abor-

tion or death of the offspring of an exposed individual.

Exposure of a mother to certain mutagenic chemicals during

pregnancy may result in cancer developing in her offspring

many years later.

Plate 3.2 Left: 500ml emergency eye wash bottle. Squeezing

the bottle gently sprays the eye. The waste liquid ﬂows

through a tube to the sink or collecting vessel. Instructions for

use are printed in green on the bottle. Right: Protective eye-

shields with closed in sides. The goggles are made from poly-

carbonate.

Teratogen:Can damage an unborn foetus causing congenital

malformations, foetal death, or cancer in the offspring many

years later.

Note: Further details regarding the toxicity of chem-

icals and a list of the reported acute and chronic

effects of some chemicals can be found in the WHO

Laboratory Biosafety Manual.

Chemical manufac-

turers upon request will provide data sheets for the

chemicals they produce. Essential safety information

can also be found on the labels of containers.

CORROSIVE CHEMICALS

A corrosive chemical is one that when ingested,

inhaled, or allowed to come in contact with skin can

destroy living tissue and is also capable of damaging

inanimate substances.

Examples of corrosive chemicals include phenol,

strong acids such as concentrated sulphuric acid,

nitric acid, glacial acetic acid, trichloroacetic acid,

o-phosphoric acid, caustic alkalis such as sodium

hydroxide (caustic soda), and potassium hydroxide

(caustic potash), and some concentrated disinfectant

solutions.

Safe storage and use

Storage

Corrosive chemicals should be stored at low level to

avoid injury which could be caused if such chemicals

were accidentally knocked off a shelf. Do not store

potassium hydroxide or sodium hydroxide in a

bottle having a ground glass stopper because these

chemicals absorb carbon dioxide from the air form-

ing carbonates which can cement the stopper in the

bottle.

Safe use

 Never mouth-pipette a corrosive chemical (see

also previous text). The accidental swallowing of

a corrosive chemical can cause severe internal

injury.

 Always pour a corrosive chemical at below eye

level, slowly and with great care to avoid splash-

ing.

 Wear suitable protective gloves and a face visor

or at least eyeshields, when opening a container

of a corrosive chemical and when pouring it.

Place a cloth over the neck and cap of the

container when opening it.

 Dissolve a solid corrosive chemical such as

sodium hydroxide in water with great care, mix-

ing in small amounts at a time to dissipate the

heat produced.

78 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

3.5

 When diluting concentrated acids, particularly

sulphuric acid, always add the acid to the water.

NEVER ADD WATER TO ACID. Adding water to

sulphuric acid can produce sufﬁcient heat to

break a glass container.

 When weighing corrosive chemicals, e.g. phenol,

avoid damaging the balance by ensuring the

chemical does not spill on the balance pan or

other metal parts. Use a suitable weighing con-

tainer and remove this from the balance pan

when adding or removing the chemical.

 Always use a strong carrier to transport bottles of

corrosive chemicals.

Accidents involving corrosive chemicals

The treatment of burns caused by corrosive chemi-

cals is described in subunit 3.8. See later text for the

management of spillages involving corrosive

chemicals.

EXPLOSIVE CHEMICALS

Heat, ﬂame, knocks or friction can cause explosive

chemicals to explode. Examples of explosive chemi-

cals include:

 Sodium azide: This can form explosive products

when in contact with metals such as copper and

lead, e.g. in pipes.

 Perchloric acid: If allowed to dry on woodwork,

brickwork or fabric, this chemical will explode

and cause a ﬁre on impact.

 Picric acid and pricrates: Picric acid must be

stored under water. If allowed to dry it can be-

come explosive. This can occur if the chemical is

left to dry in pipes without being ﬂushed away

with an adequate amount of water.

 Diethyl-ether and other ethers:When exposed to

air and sunlight, ether can form shock-sensitive

explosive peroxides.

Important: Always read carefully the manufacturers’

instructions regarding the storage and handling of

explosive chemicals. Few techniques in district lab-

oratory work require the use of explosive chemicals.

ENVIRONMENTALLYDANGEROUS CHEMICALS

These are substances that are dangerous for the en-

vironment because they can cause immediate or

long term harm to aquatic life, fauna and ﬂora, or

pollute the atmosphere. Laboratory staff have a duty

to avoid chemical pollution of the environment.

Those in charge of district laboratory services

must ensure that the drainage and waste disposal

systems of district laboratories are safe, adequate

and in good repair. Hazardous chemicals and

reagents must not be discharged into open drains or

disposed of on open ground. Sufﬁcient water must

be used when ﬂushing hazardous chemicals and

reagents through the plumbing system.

The sewer system should not be used to dispose

of highly toxic chemicals, water-immiscible chemi-

cals, or substances that can react with metal

drainage pipes to produce dangerously reactive

products, e.g. sodium azide or picric acid. Advice

should be obtained from a qualiﬁed safety ofﬁcer re-

garding the disposal of environmentally dangerous

laboratory chemicals.

SPILLAGECONTROL GUIDELINES

In the event of a serious chemical spill, evacuate

non-essential personnel from the affected area and

proceed as follows:

 If there is personal injury or a hazardous chemi-

cal has been spilled on clothing, remove the

clothing and immediately wash and immerse the

affected part of the body in water. If the injury is

serious, apply appropriate First Aid measures and

seek medical advice.

 If liquid chemicals (non-ﬂammable) are spilled,

place sufﬁcient dry sand or absorbent paper

around the spillage to prevent its spread and to

soak up the chemical. Wearing chemical resistant

gloves and using a plastic dustpan, collect the

material, neutralize it if a strong acid or alkali and

dispose of it safely.

Neutralization

Use 50 g/l (5% w/v) sodium bicarbonate or sodium car-

bonate to neutralize acid spills, and 10 g/l (1% v/v) acetic

acid to neutralize strong alkali spills. Clean the spillage

area with water and detergent.

 If the spillage is a volatile ﬂammable chemical,

immediately extinguish all ﬂames, e.g. from

Bunsen and spirit burners. Open the windows

and doors to allow the spillage to evaporate.

Clean the area with water and detergent.

 If the spillage is a solid chemical, wearing chemi-

cal resistant gloves and dust mask if appropriate,

collect the chemical in a plastic dustpan and dis-

pose of it safely by dissolving it in an adequate

HEALTHANDSAFETYINDISTRICTLABORATORIES 79

3.5

volume of water and ﬂushing it down the

drainage system. If water-immiscible or unsuit-

able for ﬂushing down the plumbing system, mix

the chemical with sand and dispose of it in a

deep covered waste disposal pit. Clean the

spillage area with water and detergent.

Important: Follow any special spillage control

measures recommended by the manufacturer of a

chemical and display charts showing how to manage

chemical spills.

SAFETYGUIDELINES FOR COMPRESSED AND

LIQUEFIED GASES

The use of compressed gases should be avoided

whenever possible. Where their use is necessary, the

following safety measure should be applied:

 Make sure all cylinders are clearly labelled and

correctly colour coded.

 Display warning notices on the doors of rooms

where cylinders containing ﬂammable gases are

used and stored.

 Do not keep more than one cylinder of a ﬂam-

mable gas in a room at any one time. Store spare

cylinders in a locked identiﬁed weatherproof

store at some distance from the laboratory.

 Fix securely (e.g. chain) a gas cylinder to the wall

or a solid bench to avoid it being dislodged.

 Do not locate compressed gas cylinders or lique-

ﬁed gas containers near to radiators, naked

ﬂames or other heat sources, sparking electrical

equipment, or in direct sunlight.

 Always turn off the main high-pressure valve

when the equipment is not in use and when the

room is unoccupied.

 Use a trolley to support compressed gas cylin-

ders when they are being transported (transport

with caps in place).

 Do not incinerate single use gas cylinders.

Note: Gases for ﬁxed items of equipment should

be connected by a drop level safety cock to per-

manent pipework using screwed union connectors.

Bunsen burners should also be controlled by a

safety cock. Installation of piped compressed air,

vacuum or gas system must be undertaken by a

qualiﬁed person.

80 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

3.5

Summary: preventing accidents involving chemicals and reagents

● Identify and list all chemicals kept in the laboratory and stores. Maintain an up to date inventory and

information sheets on each chemical including its use, storage requirements, any known risk, and

instructions for its safe use. Request safety data sheets from manufacturers.

● Before opening a chemical, always read the safety (S) and risk (R) phrases written on the label. Know

the hazard symbols for chemicals.

● Label clearly all reagents with their name, date of preparation, expiry date (if of limited shelf-life), and

hazard symbol if indicated. Prepare written instructions on how to prepare each reagent safely.

● Store each chemical and reagent correctly, making sure chemicals that can react dangerously

together, i.e. incompatible chemicals, are not stored together (see Chart 3.3).

● Store stock containers of liquid acids, alkalis, corrosive and ﬂammable chemicals at ﬂoor or low level

in drip trays to contain any spillage.

● Keep chemicals and reagents out of direct sunlight and do not allow them to overheat.

● Ensure the caps of containers are airtight and tightly closed, particularly of chemicals that are volatile,

ﬂammable, hygroscopic, deliquescent or have a toxic or irritating vapour.

● Do not use rubber liners in the caps of bottles containing iodine, ether, xylene or other chemical

which attacks rubber. Do not use ground glass stoppers in bottles containing potassium or sodium

hydroxide or other chemical that absorbs carbon dioxide from the air.

● When opening a corrosive chemical or one with an irritating vapour, use a cloth over the cap and

neck of the container and wear chemical resistant protective gloves.

● Keep the laboratory well ventilated when using hazardous chemicals particularly those that are

ﬂammable or have a toxic or irritating vapour. Whenever possible use a fume cupboard.

● When preparing reagents, always mix chemicals with care. Wear appropriate footwear and

protective clothing, e.g. laboratory overall, gloves, dust mask, eye goggles or face visor.

● Ensure an eyewash bottle is available and accessible.

● Never mouth-pipette, taste, or inhale a chemical or reagent.

● Always wash the hands immediately after handling chemicals.

● Use appropriate hazard symbols on the doors of cupboards storing dangerous chemicals.

● Extinguish all open ﬂames when using ﬂammable and oxidizing chemicals and reagents. Ensure ﬁre

ﬁghting equipment is available and accessible.

● Understand how accidents involving chemicals and reagents can occur and know what to do to

control and extinguish a chemical ﬁre, treat a chemical spillage (see later text), and apply First Aid.

● Use plenty of water when washing toxic, corrosive, ﬂammable and volatile reagents down the

plumbing system, e.g. during staining.

Mercury from a broken thermometer: Do not discard mercury down the sink. Wearing gloves, carefully collect the

mercury using a stiff card and dustpan and discard it in a deep covered waste disposal pit.

● Keep stores and cupboards containing stock and dangerous chemicals securely locked. Do not allow

unauthorized persons to enter the laboratory and never leave it unlocked when unoccupied.

Chart 3.3 SAFETY INFORMATION ON SOME CHEMICALS USED IN DISTRICT LABORATORIES

Important: Not all hazardous chemicals are included in this list. Always read carefully the storage

instructions and safety information printed on the container label. The source of the information in this

chart is the BDH/Merck Laboratory Supplies Catalogue.

CHEMICAL MAI N HAZARD SAFETY PRECAUTIONS

Corrosive, causing severe burns. Protect eyes, skin, clothing, and equipment.

Avoid breathing fumes. Use in well

ventilated area.

Irritant vapour Keep away from oxidizers, particularly nitric

acid, chromic acid, peroxides and

permanganates.

Flammable, with ﬂash point 40°C.

Extremely ﬂammable and volatile Keep away from sources of ignition,

with ﬂash point 18°C. chloroform, chromic acid, sulphuric acid,

nitric acid and other oxidizers. Avoid

breathing fumes. Use in well ventilated

area. Protect eyes.

See Ethanol

Corrosive Protect eyes, skin, clothing, and equipment.

Place cloth over cap before removing it or

preferably use in a fume cupboard.

Irritant vapour Keep away from mercury and halogens

such as chlorine and iodine.

Harmful if ingested or inhaled. Protect against ingestion, inhalation, and

skin contact.

Harmful if ingested. Protect against ingestion, skin and eye

Irritating to the eyes. contact.

Corrosive Protect eyes, skin, clothing and equipment.

Contact with acids liberates toxic Keep away from acids, ﬂammable

gas. chemicals, and combustible materials.

Oxidizing.

See Sodium hypochlorite solution.

Harmful if ingested or inhaled. Avoid breathing vapour. Use in a well

Irritating to the skin. Suspected ventilated area or preferably in a fume

carcinogen. Volatile with vapour cupboard.

that is anaesthetic. Toxic product Protect eyes and skin.

formed if heated. Attacks plastics Keep away from acetone.

and rubber.





Chloroform

Chlorine

solutions



Calcium

hypochlorite

bleaching

powder





Benzoic acid





Barium

chloride







Ammonia

solution

Alcohol



Acetone









Acetic acid,

glacial

HEALTHANDSAFETYINDISTRICTLABORATORIES 81

3.5

CHEMICAL MAI N HAZARD SAFETY PRECAUTIONS

Corrosive Protect eyes, skin, clothing, and equipment.

Keep away from combustible materials,

acetone and other ﬂammable chemicals.

Oxidizing

Extremely ﬂammable with ﬂash Protect eyes. Avoid breathing fumes. Use

point 39°C. in a well ventilated area or preferably in a

fume cupboard.

Irritant to eyes and respiratory Keep away from sources of ignition and

system. oxidizers.

Do not empty into drains.

Toxic if ingested, inhaled, or in Wear appropriate protection. Wash

contact with skin. immediately any affected area.

Highly ﬂammable and volatile with Keep away from sources of ignition, silver

ﬂash point 13°C. nitrate, and oxidizers.

Harmful if ingested.

Harmful if inhaled. Irritant to eyes, Protect skin and eyes. Use in a well

respiratory system, and skin. ventilate d area.

Also corrosive Keep away from oxidizers.

Extremely ﬂammable, with Keep away from sources of ignition,

ﬂashpoint 40°C. Volatile with oxidizers, iodine and chlorine. Do not

anaesthetic vapour. refrigerate. Store in opaque container, not

May form explosive peroxides plastic unless polypropylene. Do not use

when exposed to light. cap with rubber liner.

Use in well ventilated area or preferably in

a fume cupboard.

Harmful if ingested. Protect against ingestion and skin contact.

Toxic if ingested, inhaled, or in Wear appropriate protection. Use in well

contact with skin. Causes burns ventilate d area or preferably in a fume

and can cause dermatitis. Probable cupboard. Wash immediately any affected

carcinogen. area. Keep away from hydrochloric acid

Irritating and unpleasant odour. and oxidizers. Do not store below 21°C.

(Keep at 21–25°C).

Highly ﬂammable with ﬂash Keep away from sources of ignition.

point 12°C. Avoid inhaling fumes and contact with

skin.

Harmful if ingested. Irritating to Wear appropriate protection. Use in well

skin and respiratory system. May ventilated area.

cause dermatitis. Can damage eyes. Keep away from oxidizers.





Glutaraldehyde



Giemsa stock

stain (alcoholic

stain)







Formaldehyde

solution





Ethylene

glycol

(Ethanediol)



Ether, diethyl





Ethanolamine



Ethanol,

absolute



Diphenylamine







Diethylamine





Chromic acid

(reagent)

82 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

3.5

Corrosive, causing severe burns. Protect skin, eyes, clothing, and equipment.

Irritating to respiratory system. Do not breathe fumes. Use in well

Unpleasant corrosive fumes. ventilated area or preferably in a fume

Releases toxic fumes in ﬁres. cupboard.

Keep away from alkalis, chromic acid,

potassium permanganate.

Corrosive Protect eyes, skin, clothing, and equipment.

Store in opaque non-metallic container.

Irritating to eyes, respiratory Keep out of direct sunlight in a cool dark

system, and skin. place away from ﬂammable chemicals and

Stronger solutions are oxidizing. combustible materials.

Harmful if ingested, inhaled, or in Avoid skin and eye contact, and breathing

contact with skin. in vapour. Store iodine containing reagents

Irritating to eyes and respiratory in opaque container. Do not use caps with

system. rubber liners. Reacts violently with metals,

Evolves toxic fumes in ﬁres. acetylene, and ammonia.

Harmful if ingested. Irritating to Protect against ingestion, skin and

the skin. Can cause eye damage. eye contact.

As for Giemsa stain.

Toxic by inhalation. May cause Ventilate area if mercury escapes from

dermatitis. broken thermometer (discard in deep

Attacks lead piping and soldered covered pit). Avoid skin contact.

joints. Keep away from ammonia, bromine,

Evolves toxic fumes in ﬁres. azides, ethylene oxide.

Verytoxic if ingeste d. Toxic in Protect against ingestion and contact with

contact with skin and can cause skin. Minimize use. Wash hands

burns. immediately after use.

Keep in locked cupboard.

Verytoxic if ingeste d, inhaled, or Wear appropriate protection. Minimize

in contact with skin. use. Wash hands immediately after use.

Keep in locked cupboard.

Highly ﬂammable with ﬂashpoint Keep away from sources of ignition,

12°C. Volatile and hygroscopic. sodium hypochlorite, nitric acid,

chloroform, hydrogen peroxide.

Toxic if ingested or inhaled. Can Avoid breathing vapour. Protect skin and

cause dermatitis and damage optic eyes. Use in a well ventilated area or

nerve and central nervous system. preferably in a fume cupboard.

Corrosive, causing severe burns. Protect skin, eyes, clothing, and equipment.

Has irritating and harmful vapour. Avoid breathing fumes. Preferably use in a

fume cupboard. Use an eyewash bottle

Oxidizing immediately if acid enters eye.

Keep away from alkalis, metals, acetic acid,

chromic acid, reducing agents, ﬂammable

chemicals and combustible materials.





Nitric acid,

concentrated

(fuming)





Methanol

(Methyl

alcohol)



Mercury 11

nitrate

(Mercuric

nitrate)



Mercury 11

chloride

(Mercuric

chloride)



Mercury

Leishman

stock stain





Iron 111

chloride (Ferric

chloride)





Iodine







Hydrogen

peroxide

solution



Hydrochloric

acid,

concentrated

HEALTHANDSAFETYINDISTRICTLABORATORIES 83

3.5

CHEMICAL MAI N HAZARD SAFETY PRECAUTIONS

Toxic in contact with skin or if Protect skin, eyes, clothing, and equipment.

ingested or inhaled. Wash immediately any affected area.

Corrosive and hygroscopic. Keep container tightly closed. Store away

Oxidizes and turns pink on from oxidizers.

exposure to light.

Corrosive Protect skin, eyes, clothing, and equipment.

Evolves toxic fumes in ﬁres.

Toxic if ingested, inhaled, or in Wear appropriate protection.

contact with skin.

Evolves toxic fumes in ﬁres.

Explosive when dry. Can form Ensure chemical is always covered with

highly explosive salts with many water. Do not leave chemical to dry in

metals and explosive calcium pipes.

picrate when in contact with Keep away from reducing agents.

concrete. Note: If the water on top of the chemical has

evaporated, submerge the container in a bucket of

water overnight. Loosen cap carefully and ﬁll to

the top with water (wear gloves and eyeshields).

Verytoxic if ingeste d, inhaled, or Wear appropriate protection. Wash

in contact with skin. immediately any affected area.

Contact with acid liberates very Keep in a locked cupboard away from

toxic gas. acids.

Do not empty into drains.

Irritating to the eyes, respiratory Protect eyes and skin.

system, and skin. May cause Avoid breathing dust.

dermatitis.

Corrosive Protect skin, eyes, clothing, and equipment.

Pellets are deliquescent. Store away from acids.

Do not use reagent bottles with glass

stoppers.

Harmful in contact with skin and Avoid contact with skin and eyes.

if ingested.

Oxidizing Keep away from combustible materials,

ﬂammable chemicals, glycerol, ethylene

glycol, sulphuric acid.

Harmful if ingested.

Harmful if ingested. Irritating to Wear appropriate protection and avoid

skin and respiratory system. breathing in chemical.

Can damage the eyes.

Harmful if ingested and in contact Wear appropriate protection and avoid

with skin. inhaling powder.





Saponin powder





Salicylic acid







Potassium

permanganate





Potassium

oxalate



Potassium

hydroxide,

pellets and

solutions





Potassium

dichromate



Potassium

cyanide





Picric acid,

(solid)



o-Phosphoric

acid



Phenol

84 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

3.5

Corrosive and irritating to the eyes Protect skin, eyes, clothing, and equipment.

and skin. Keep away from ammonia solution,

May ignite combustible materials. ethanol, charcoal, and combustible

materials. Causes brown staining.

Verytoxic if ingeste d, inhaled, or Avoid contact by wearing appropriate

by skin contact. Mutagen. clothing. Do not inhale dust. Wash

Contact with acids liberates toxic immediately any affected area.

gas. Toxic gas liberated in ﬁres. Keep in a locked cupboard away from

Violent reaction occurs if water is acids and metals.

added to heated solid. Do not ﬂush down copper or lead drainage

Reacts with copper, lead, mercury systems.

to form explosive metal azide salts.

Harmful if ingested. Protect from skin contact. Keep away from

Contact with acid liberates toxic acids, ﬂammable chemicals and combustible

gas. May cause ﬁre. material.

Toxic if ingested. Irritating to eyes Protect skin and eyes.

and skin. Liberates toxic gas in Keep away from acids.

contact with acids.

Corrosive. Causes severe internal Protect skin and eyes, clothing, and

injury if ingested. equipment.

Deliquescent (pellets). Store in dry place, away from acids, methanol,

Heat evolved when mixed with and chloroform. Do not use reagent bottles

water. with ground glass stoppers.

Corrosive and toxic if ingested or Protect skin, eyes, clothing, and equipment.

inhaled. Irritating vapour. Use in well ventilated area.

May evolve toxic fumes in ﬁres. Keep away from acids, methanol and

Liberates toxic gas in contact with oxidizers.

acids.

Toxic if ingested. Do not breathe dust.

*sodium nitrosopentacyanoferrate III

Toxic if ingested. Protect against skin contact.

Keep away from combustible materials and

ﬂammable chemicals.

Oxidizing

Harmful if ingested, inhaled, or in Avoid contact with eyes and skin. Wear

contact with skin or eyes. appropriate protection.

Irritating to eyes and skin. Protect eyes and skin. Use in well

ventilated area.

Corrosive, causing severe burns. Protect skin, eyes, clothing, and equipment.

Toxic vapour. Avoid inhaling fumes.

Never add water to conc. sulphuric acid.

Keep in dry place away from alkalis,

potassium permanganate, perchlorates,

chlorates and ﬂammable substances.



Sulphuric acid





Sulphosalicylic

acid





Sulphanilic

acid





Sodium nitrite



Sodium

nitroprusside*



Sodium

hypochlorite

solution



Sodium

hydroxide,

pellets and

solutions



Sodium

ﬂuoride





Sodium

dithionite



Sodium azide



Silver nitrate

HEALTHANDSAFETYINDISTRICTLABORATORIES 85

3.5

CHEMICAL MAI N HAZARD SAFETY PRECAUTIONS

Toxic and harmful if ingested. Minimize exposure.

Carcinogen. Wear appropriate protection.

Highly ﬂammable, with ﬂash point Keep away from sources of ignition.

4°C. Volatile. Wear appropriate protective clothing.

Keep away from oxidizers and do not

Harmful if ingested, inhaled, or by empty into drains.

skin contact. May cause dermatitis.

Vapour can be irritating to the eyes.

Toxic if ingested or inhaled. Minimize exposure and wear appropriate

Carcinogen. Irritating to the eyes. prote ction.

Reacts violently with acids. Keep away from acids.

Corrosive and hygroscopic. Protect skin, eyes, clothing, and equipment.

Unpleasant odour that is irritating

to the eyes.

May evolve toxic fumes in ﬁres.

As for Giemsa stain.

Harmful if inhaled or in contact Protect from skin contact and use in well

with skin. May cause dermatitis. ventilated area.

Flammable with ﬂashpoint 25°C. Do not keep in plastic containers unless

polypropylene. Do not use caps with

rubber liners.





Xylene

Wrights stain



Trichloroacetic

acid



o-Toluidine

solution







Toluene



o-Tolidine

86 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

3.5

CHEMICALS AND REAGENTS LISTED BY HAZARD

Extremely ﬂammable

 Acetone

 Diethylamine

 Ether, diethyl

Highly ﬂammable

 Acetone-alcohol

 Acid alcohol

 Alcoholic stains: Giemsa, Leishman,

Wrights, May Grunwald

 Ethanol and alcohol

reagents

 Methanol

 Methylated spirit

 Toluene

Oxidizing (ﬁre-promoting)

 Calcium hypochlorite

 Chromic acid

 Hydrogen peroxide (strong)

 Nitric acid

 Perchlorates

 Potassium permanganate

 Sodium nitrite

Toxic

 Cadmium sulphate

 Diphenylamine

 Formaldehyde solution

 Lactophenol

 Mercury

Toxic continued

 Mercury 11 chloride

(Mercuric chloride)

 Methanol

 Phenol

 Picric acid

 Potassium cyanide

 Sodium azide

 Sodium ﬂuoride

 Sodium nitrite

 Sodium nitrosopenta-

cyanoferrate 111

(Sodium nitroprusside)

 Thiomersal

 Thiosemicarbazide

 o-Tolidine

 o-Toluidine

Harmful

 Aminophenazone

 Ammonium oxalate

 Auramine phenol stain

 Barium chloride

 Benedicts reagent

 Benzoic acid

 Carbol fuchsin stain

 Cetylpyridinium chloride

 Chloroform

 Copper 11 sulphate

 Dobell’s iodine

Harmful continued

 Ethylenediaminetetraacetic

acid (EDTA)

 Ethylene glycol (Ethanediol)

 Formol saline

 Glycerol jelly

 Glutaraldehyde

 Iodine

 Iron 111 chloride

(Ferric chloride)

 Lugol’s iodine

 Methylated spirit

 Naphthylamine

 p

-Nitrophenyl

 Oxalic acid

 Potassium oxalate

 Potassium permanganate

 Salicyclic acid

 Saponin

 Sodium deoxycholate

 Sodium dithionite

 Sodium dodecyl sulphate

 Sodium tetraborate

 Sodium tungstate

 Stains (powder form):

 acridine orange

 auramine O

 brilliant cresyl blue

 crystal violet

3.6 Equipment and

glassware hazards

Fire, electric shock, and injury from moving compo-

nents are hazards associated with the use of equip-

ment. Most glassware hazards are associated with

breakages and the use of damaged glassware.

HEALTHANDSAFETYINDISTRICTLABORATORIES 87

3.5–3.6

– do not position e quipment where movement

of its components could cause injury.

– do not loc ate equipment in a place where

access to it or cleaning will be difﬁcult.

– make sure the e quipment is level.

– do not overcrowd a b ench with equipment

because this will reduce the working area,

and increase the risk of the equipment being

damaged from chemical spills and splashes

or items being placed on the equipment.

 Make sure ventilation is adequate:

– follow the manufacturer’s instructions.

– do not cover or obstruct ventilation open-

ings.

– place wire mesh over ventilation grills to

prevent insects and rodents entering.

– make sure the chimney apertures of gas or

kerosene operated refrigerators and the

burner aperture of a ﬂame photometer are

not obstructed or located under a shelf.

– provide good ventilation when charging acid

rechargeable batteries.

 Use a qualiﬁed electrician and follow the manu-

facturer’s instructions when installing electrical

equipment. Ensure:

– the volt age of the new equipment is the

same as that of the electricity supply in the

laboratory and the voltage selector switch is

set correctly.

– the power re quired by the instrument does

not exceed the power supply circuit of the

laboratory.

– the e quipment is wired correctly using a fuse

of the correct rating, and the system has a

grounded conductor. The laboratory should

Harmful continued

 Giemsa

 Harris’s haematoxylin

 malachite green

 May Grunwald

 methylene blue

 neutral red

 toluidine blue

 Sulphanilic acid

 Thiourea

 Toluene

 Xylene

Irritant

 Acetic acid, glacial

 Ammonia solution

 Calcium chloride

Irritant continued

 Formaldehyde solution

 Hydrogen peroxide

 Lactic acid

 Naphthylethylenediamine

dihydrochloride

 Potassium dichromate

 Sodium carbonate

 Sulphosalicylic acid

 Zinc sulphate

Corrosive

 Acetic acid, glacial

 Ammonia solution

 Calcium hypochlorite

 Chromic acid

 Fouchet’s reagent

Corrosive continued

 Hydrochloric acid

 Nitric acid

 Phenol

 o-Phosphoric acid

 Potassium hydroxide

 Silver nitrate

 Sodium hydroxide

 Sodium hypochlorite

 Sulphuric acid

 Thymol

 Trichloroacetic acid

Explosive

 Picric acid (when dry)

 Sodium azide

PREVENTING EQUIPMENT RELATED ACCIDENTS

Safe positioning and installation of equipment

 When installing and positioning equipment

consider both safety and convenience:

– do not place ele ctrical equipment near to

water, in direct sunlight or close to where

chemicals and reagents are used or stored.

Equipment related accidents in district

laboratories

The safe use of equipment is dependent on:

● equipment being installed and positioned

correctly.

● equipment being used as instructed by the

manufacturer.

● equipment being cleaned, inspected,

serviced and repaired correctly.

● staff being well instructed in the correct use,

cleaning and maintenance of equipment.

● the district laboratory coordinator ensuring

standard operating procedures (SOPs) and

maintenance schedules for equipment exist

and are implemented.

have sufﬁcient earthed outlets. Circuit-

breakers and earth-fault interrupters should

be ﬁtted to all laboratory circuits.*

*Circuit-breakers protect wiring from being over-

loaded with electric current. Earth-fault interrupters

protect people from electric shock.

– the c able used is not longer than is

necessary, has no joins, is well insulated

and not positioned near water or hot

surfaces.

– the use of multiple adaptors, temporary con-

nections, and extension leads is avoided

because these can lead to overheating and

bad connections.

Safe use of electrical equipment

 Do not purchase or accept donated equipment

unless accompanied by a manufacturer’s instruc-

tion manual written in a language that can be

understood or accurately translated.

 Use the equipment correctly:

– whenever possible have new e quipment

demonstrated by the supplier.

– prepare and display easy to underst and

instructions and safety precautions near to

the equipment.

 Make sure staff are well instructed and trainees

adequately supervized:

– to use and clean corre ctly the equipment in

their care.

– to dry their hands and ﬂoor underfoot b efore

using electrical equipment.

– to switch off and disconne ct the electricity

supply to an instrument by removing the

plug at the end of a day’s work and during

an electric storm (excluding refrigerators and

incubators).

– to stop using and report imme diately any

malfunction of equipment.

– to obt ain the help of an electrician to

check the electricity circuit should a fuse

‘blow’.

– to apply First Aid following an e quipment

related injury (see subunit 3.8).

– to ke ep careful records of equipment main-

tenance, servicing and repair.

Important: District laboratories should b e supplied

with a dry chemical ﬁre extinguisher to control an

electric ﬁre (see also subunit 3.7).

88 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

3.6

Cleaning, maintenance, inspection and

servicing of equipment

 Perform cleaning, maintenance and servicing as

recommended by the manufacturer:

– prepare S OPs and a written maintenance

schedule for each piece of equipment with a

checklist of the tasks to be performed at

speciﬁed times.

– always turn off and disconne ct equipment

before carrying out cleaning, maintenance,

and inspections.

– inspe ct equipment regularly for corrosion,

worn components, damaged insulation,

frayed cable, loose connections, fungal

growth, insect and rodent infestation.

 Hold stocks of essential components with their

part numbers and sources of supply. If unable to

obtain spares from the manufacturer make sure

the speciﬁcations of alternatives are correct, e.g.

dimensions, fuse ratings, voltage and wattage of

lamps etc. When purchasing spares, always state

the model number of the equipment and date it

was purchased, and the supplier’s part number.

Note: The use and maintenance of different items of

equipment can be found in Chapter 4. Publications

covering the safety and maintenance of laboratory

equipment include WHO Maintenance and repair of

laboratory, diagnostic, imaging and hospital equip-

ment

and the WHO Laboratory Biosafety Manual,

PREVENTING GLASSWARERELATED ACCIDENTS

Although plasticware is increasingly being used in

district laboratories, glass pipettes, capillaries, test

tubes, specimen containers, ﬂasks, beakers, slides

and coverglasses continue to be used because they

are easier and cheaper to obtain, clean, and reuse.

For some items there are no appropriate plastic

alternatives. It is therefore essential for district lab-

oratories to include in their code of safe working

practices, effective measures to prevent injury and

infection from broken and damaged glassware.

Correct purchasing of glassware

 Avoid purchasing glassware classiﬁed as ‘dispos-

able’. Such glassware is usually thin walled and

not intended for cleaning and reuse. If needing

to reuse cover glasses, purchase thicker No. 2

glasses.

 Ensure glassware that is to be used at high temp-

erature, or heat sterilized is made from Pyrex or

other heat resistant glass.

Safe handling of glassware

 Use appropriate plastic containers for soaking

and decontaminating used glassware. Minimize

damage, breakage, and risk of injury by:

– not overﬁlling cont ainers,

– using separate cont ainers for fragile cover

glasses, slides, and sharp ended Pasteur

pipettes.

 Before reuse, inspect glassware, particularly

tubes, pipettes and specimen containers for

cracks, broken and chipped ends.

 Never centrifuge cracked tubes or bottles.

 Flame until smooth the sharp ends of pipettes,

and the damaged rims of test tubes.

 Wear protective gloves when cleaning glassware

and avoid overcrowding drainage racks.

 Store glassware safely. Do not leave it in

open trays or other places where it can be

damaged.

 To avoid spillages and breakages, use racks or

trays to hold specimen containers and other

bottles.

Safe management of breakages

 Wear heavy duty gloves and use forceps to

collect broken glass. A piece of plasticine is use-

ful for collecting glass fragments.

 Discard broken glass in a separate puncture

resistant waste bin marked ‘Sharps’ and dispose

of the contents safely. Do not allow the bin to

overﬂow.

 Never leave used haematocrit (capillary) tubes

on a bench from where they can roll to the

ﬂoor.

 When a breakage on the bench or ﬂoor occurs,

immediately collect the broken glass and

make sure the area is brushed and cleaned

well.

 Wear suitable closed toe footwear. Wear protec-

tive gloves when unpacking new glassware.

Unpack the glassware in a safe place where any

broken glass from packing cases can be safely

contained.

 Inspect regularly places where glassware is

stored for glass fragments, particularly drawers or

containers where glass pipettes, cover glasses,

and slides are kept.

 Treat immediately any glass injury and cover

cuts with an appropriate dressing (see subunit

3.8).

HEALTHANDSAFETYINDISTRICTLABORATORIES 89

3.6–3.7

3.7 Fire safety

A signiﬁcant ﬁre risk exists in small district labora-

tories due to the frequent use of matches and open

ﬂames in close proximity to highly ﬂammable chem-

icals and reagents such as acetone, diethyl ether,

methanol, methylated spirit, acid alcohol, and stains

that are alcohol-based.

Fire may also be caused by overheating in faulty

poorly maintained electrical equipment, overloading

of electrical circuits, use of adaptors, or overheating

of electrical motors due to inadequate ventilation.

Gas tubing or electric cables that are worn or too

long are also ﬁre risks.

It is essential for district laboratory technical and

auxiliary staff to receive adequate instruction and

training in ﬁre safety and appropriate ﬁre ﬁghting. A

local ﬁre ﬁghting service is unlikely to be available in

rural district areas.

Injury, damage and loss caused by ﬁre can be

minimized when laboratory staff:

– understand how ﬁres are caused and spread.

– reduce the risk of ﬁre by following ﬁre safety

regulations at all times.

– know what to do if there is a ﬁre in their

laboratory.

– know how to use ﬁre ﬁghting equipment.

– know how to apply emergency First Aid for

burns.

Important: Those in charge of district laboratory

services must provide adequate training of labora-

tory staff in ﬁre safety and equip district laboratories

with essential ﬁre ﬁghting equipment.

FIRE FIGHTINGEQUIPMENT

Fire ﬁghting equipment for district laboratories

should include:

 Buckets of water to extinguish paper, fabric and

wood ﬁres. Water, however, must never be used

to extinguish an electrical ﬁre or one caused by

a ﬂammable chemical.

 Buckets of sand or dry soil (kept free of refuse)

to smother ﬂames and contain and extinguish a

free ﬂowing liquid ﬁre.

 Fire blanket(s) made from heavy cotton twill

treated with a ﬁre retardant chemical or prefer-

ably a manufactured ﬁre blanket made from

woven ﬁbre glass sandwiched between a ﬁre

retardant material, to extinguish ﬁre on personal

clothing or a small ﬁre on the ﬂoor or bench.

 Dry powder chemical ﬁre extinguisher to

extinguish electrical ﬁres and ﬁres caused by

ﬂammable liquids.

Whenever possible the laboratory should be

ﬁtted with a battery operated smoke detector alarm.

It should be tested at regular intervals as

recommended by the manufacturer.

To alert those in and adjacent to the laboratory of

a ﬁre danger, a ﬁre alarm such as a loud handbell

or gong should be kept in a prominent place. When

facilities allow, a ﬁre alarm system should be

installed.

90 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

3.7

Fire hazard of some commonly used chemicals

CHEMICAL FLASH POINT

CLASSIFICATION

Diethyl ether 40°C Extremely ﬂammable

Class 1A

Acetone 18°C Extremely ﬂammable

Class 1B

Toluene 4°C Highly ﬂammable

Class 1B

Methanol 12°C Highly ﬂammable

Class 1B

Ethanol, 13°C Highly ﬂammable

absolute Class 1B

Isopropanol 12°C Highly ﬂammable

Class 1B

Ethanol, 70% 21°C Highly ﬂammable

Class 1B

Xylene 25°C Flammable

Class 1C

Acetic acid, 40°C Flammable

glacial Class 11

Classiﬁcation terminology: Flash points with boiling points

are used to classify liquids by European terminology as

extremely ﬂammable, highly ﬂammable or ﬂammable or by

United States terminology as ﬂammable Class 1A, Class 1B,

Class 1C, or combustible liquids Class 11or Class 111.

Important ﬁre risk reagents: Acid alcohol, alcohol/acetone

decolorizers, and stock alcoholic Romanowsky stains, e.g.

Leishman and Giemsa are classiﬁed as Highly ﬂammable,

Class 1B.

Summary: Guidelines to reduce the risk

of ﬁre in district laboratories

● Do not allow smoking in the laboratory or in

adjacent outpatient waiting areas or corri-

dors. Display large No smoking signs.

● Keep only small amounts of highly ﬂam-

mable chemicals and reagents (classiﬁed in

subunit 3.5) on laboratory benches and

shelves. Whenever possible use plastic dis-

pensing containers that can be closed when

not in use. Keep them in a tray to retain the

ﬂammable liquid should a spillage occur.

● Store stock ﬂammable chemicals and

reagents preferably in an outside cool store,

in trays, well away from oxidizing and other

incompatible chemicals (see subunit 3.5). If

this is not possible store the stock containers

at ground level in trays in a metal or thick

plywood box with a tight ﬁtting lid.

● When lighting and using a spirit burner,

Bunsen burner, or ring burner, always

check that there is no ﬂammable chemical

or reagent nearby.

● Be particularly careful when heating carbol

fuchsin stain on slides in the Ziehl-Neelsen

technique. Use only a small lighted swab

and extinguish it immediately after use.

Keep the ﬂame well away from acid alcohol,

acetone, methanol, methylated spirits, ether,

stains such as Leishman and Giemsa, and

other ﬂammable reagents.

● Promote safety awareness by displaying

clearly written ﬁre instruction notices in the

laboratory, review regularly ﬁre safety rules

and practise every 6 months what to do in

the event of a ﬁre.

● Install electrical equipment safely (see sub-

unit 3.6). Inspect and maintain it. Do not

allow untrained personnel to repair equip-

ment.

● Keep the laboratory well ventilated, when

using ﬂammable chemicals and reagents to

prevent any build-up of ﬂammable vapours

and gases.

● Keep containers of ﬂammable chemicals

and reagents tightly closed to prevent the

escape of ﬂammable vapours.

● If the laboratory is ﬁtted with ﬁre doors,

keep these closed. Make sure there is a safe

unobstructed marked exit route(s) from the

laboratory.

● Whenever possible, ask advice from a

professional Fire Safety Ofﬁcer on how to

implement and improve ﬁre safety.

Note: The control of ﬁres involving ﬂammable

chemicals is described in subunit 3.5. The emer-

gency treatment of burns in subunit 3.8. Further

information can be found in the WHO Laboratory

Biosafety Manual

3.8 Emergency First Aid

Knowing what to do immediately an accident occurs

can help to reduce suffering and the consequences

of serious accidents. In some situations, First Aid can

be life saving, e.g. by resuscitation or the control of

bleeding. It can also prevent an injured person’s

condition from worsening, e.g. by protecting and

treating wounds, placing a person in the best poss-

ible position, offering reassurance, and seeking

immediate assistance.

TRAININGIN FIRSTAID

All laboratory workers should receive a practical

training in First Aid, with particular attention being

paid to the types of accidents that may occur in the

laboratory. They should also know what emergency

action to take if an outpatient or blood donor

collapses in the laboratory.

Training must be given by a person qualiﬁed to

teach First Aid. A certiﬁcate of competence should

be issued to those who complete the course suc-

cessfully. Refresher courses should be held every

3–4 years.

First Aid equipment

An adequately equipped First Aid box and eyewash

bottle should be kept in the laboratory in a place

that is known and accessible to all members of staff.

The First Aid box should be clearly identiﬁed by a

white cross on a green background. It should be

made of metal or plastic to prevent it being dam-

aged by pests and to protect the contents from dust

and damp. The contents should be inspected

regularly.

Recommended contents of a laboratory First Aid box

 Clear instructions on how to apply emergency treatment

of cuts, bleeding, heat burns, chemical burns, chemical

injury to the eye, swallowing of acids, alkalis, and other

poisonous chemicals, treatment of fainting, electric shock,

and how to perform emergency resuscitation (illustrated).

 Sterile unmedicated dressings to cover wounds.

 Absorbent cotton wool.

 Triangular and roll bandages and safety pins.

 Sterile adhesive waterproof dressings in a variety of sizes.

HEALTHANDSAFETYINDISTRICTLABORATORIES 91

3.7–3.8

 Sterile eyepads with attachment bandages.

 Roll of adhesive tape.

 Scissors.

 Sodium bicarbonate powder and boric acid powder.

 Equipment for person giving First Aid (mouthpiece,

gloves).

Eyewash bottle

An eyewash bottle of the type shown in plate 3.2

(subunit 3.5) is suitable for district laboratories.

Clean tap water can be used to wash the eye. If no

clean tap water is available, sterile water or isotonic

saline should be used (kept next to the eyewash

bottle).

EMERGENCY FIRST AID PROCEDURES

First Aid applied to the laboratory should include

emergency management of the following:

● Cuts, needlestick injuries ● Electric shock

● Bleeding ● Heat burns

● Resuscitation ● Chemical burns

● Fainting ● Poisoning

A First Aid chart giving the immediate treatment of

cuts, bleeding, burns, poisoning, shock and resusci-

tation should be prepared and displayed in the

laboratory.

Emergency treatment of cuts and bleeding

If the cut is small:

– wash with soap and water.

– apply pressure with a piece of cotton wool.

– disinfect the area with a skin antiseptic.

– cover with a water-proof dressing.

Note: If the cut has been caused by contaminated

glassware or is a needlestick injury, encourage bleed-

ing before washing well with soap and water. Apply

a skin antiseptic and cover the area with a water-

proof dressing. Seek medical advice.

If there is serious bleeding from a limb:

– raise the injured limb to reduce the bleeding.

– apply pressure with a clean dressing backed with

cotton wool.

– bandage the dressing in position.

– immediately seek medical assistance.

Bleeding from the nose

– seat the person upright with the head slightly

forward.

– tell the person to pinch ﬁrmly the soft part of

their nose for about 10 minutes and breathe

through their mouth.

– if the ble eding does not stop, seek medical

advice.

Emergency resuscitation when a person stops

breathing

If a person stops breathing following an electric

shock or for any other reason, artiﬁcial respiration

(ventilation) must be applied as soon as possible (if

the brain is deprived of oxygen for more than about

4 minutes, permanent brain damage will occur). The

person may also require heart compression if there

is circulatory arrest, i.e. heart is not beating.

Mouth-to-mouth respiration (ventilation)

There are several ways to perform artiﬁcial respir-

ation. The most effective is mouth-to-mouth:

1 Lie the unconscious person on the ﬂoor.

Supporting the neck, tilt the head backwards

with the chin pushed upwards as shown in Fig.

3.9(1).

Important: This position is essential to keep the

person’s airway open.

2 If the person does not start to breathe, begin

immediately mouth-to-mouth respiration:

– open your mouth wide and t ake a deep

breath.

– pinch the person’s nostrils together with

your ﬁngers.

– press your lips around the person’s mouth.

– blow into the person’s mouth (air will pass to

the lungs) until the chest is seen to rise.

– remove your mouth and watch the chest fall

as the air escapes from the lungs.

– repeat the inﬂation at the normal rate of

breathing, i.e. 10–15 breaths per minute.

Note: Give the ﬁrst few breaths rapidly to

saturate the person’s blood with oxygen.

If you cannot get air into the person’s chest, check

that the head is tilted sufﬁciently far back, you have

a ﬁrm seal around the mouth, you have closed the

nostrils sufﬁciently, and the airway is not obstructed

by vomit, blood, or a foreign body.

Heart not beating

3 If after the ﬁrst two inﬂations, natural breathing is

not restored, check whether the heart has

stopped beating.

92 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

3.8

Indications that the heart has stopped beating

are:

 person remaining or b ecoming grey-blue.

 no c arotid pulse being felt (see Fig. 3.10).

 pupils of the eye appearing widely dilate d.

Take immediate action to restart the heart while

at the same time continuing mouth-to-mouth

respiration:

– Be gin external heart compression by placing

the heel of your hand on the lower half of

the person’s breastbone and cover this hand

with the heel of your other hand as shown in

Fig. 3.11 (the palms and ﬁngers of your hand

should be raised away from the person’s

chest so that pressure is not applied over the

ribs).

– With your arms straight, press down rapidly

on the breastbone (once every second),

depressing it about 4 cm (1 in) then release

the pressure without removing your hands.

– Look to se e whether there is an improve-

ment in the person’s colour indicating a

return of circulation. If there is no improve-

ment, continue compression and mouth-to-

mouth respiration.

If resuscitating by yourself, apply 15 heart

compressions followed by 2 quick lung

inﬂations and then repeat.

If there is someone else to help, apply 5

heart compressions, followed by 1 deep

inﬂation. The person carrying out the mouth-

to-mouth respiration should feel for a carotid

pulse.

4 Once natural breathing has b een restored

and the heart is beating, place the person in

the recovery position (see Fig. 3.8). This is

important because the person may vomit

and in this position there will be no danger

of choking.

5 Obt ain further medical assistance at the

earliest opportunity.

Note: Other forms of resuscitation will be required if

it is not possible to apply mouth-to-mouth respir-

ation. Alternative methods should therefore be

learnt.

Emergency treatment when someone faints

Emergency treatment of a faint is as follows:

– lay the person down and raise the legs above the

level of the head (see Fig. 3.7).

– loosen clothing at the neck, chest, and waist.

HEALTHANDSAFETYINDISTRICTLABORATORIES 93

3.8

Fig. 3.7 Position in which to place a person who has fainted.

Fig. 3.8 The recovery position.

Fig. 3.10 Feeling for the carotid pulse

Fig. 3.9 Mouth to mouth ventilation during emer-

gency resuscitation. If the heart has stopped beat-

ing, perform external heart compression (see text

for details)

Fig. 3.11 Position of hands over lower breast bone when performing external heart compression.

Acknowledgement: Illustrations are reproduced by permission of St John Ambulance Association

Position of sternum Cross-section through chest

– make sure the room is well-ventilated.

– reassure the person as consciousness is regained.

– gradually raise the person to the sitting position.

Sips of drinking water may be given.

Note: If breathing becomes difﬁcult, place the

person in the recovery position shown in Fig. 3.8.

Emergency treatment when someone is

electrocuted

Carry out the following:

– immediately turn off the electricity from the mains

if it can be reached easily, otherwise remove the

plug or wrench the cable free. DO NOT TOUCH

THE PERSON’S FLESH WITH YOU R HANDS

until the contact has been broken.

Important: On no account try to free an electrocuted

person from the electrical contact without using

some form of insulation material, such as a dry thick

cloth, folded laboratory coat, folded newspapers,

wooden or plastic stool or chair. If insulation is not

used, the person rescuing will also be electrocuted.

– if the person has collapsed, send immediately for

medical help and if the person is not breathing,

give artiﬁcial respiration until assistance arrives.

– Cool any burns with water.

Emergency treatment of heat and chemical

burns

Heat burns

– if clothing is alight, smother the ﬂames using a

ﬁre blanket.

– remove the person from the danger area.

– immediately plunge the burnt area into cold

water or apply a pad soaked in cold water (or any

other non-ﬂammable liquid) to the affected part

for 10 minutes.

– cover with a dry dressing.

– remove any constricting articles such as rings or

bracelets before the affected area starts to swell

and becomes blistered.

– provide frequent small cold drinks.

Note: If more than a minor burn, seek medical treat-

ment immediately. Reassurance of the casualty is

important.

Chemical burns of the skin

– wash immediately in running water for several

minutes, remove any contaminated clothing.

94 DISTRICT LABORATORYPRACTICE IN TROPICAL COUNTRIES

3.8

– neutralize with a suitable chemical as follows:

If an acid burn, neutralize with sodium

bicarbonate powder.

If an alkali burn, neutralize with boric acid

powder.

– seek medical attention.

Note: Respiratory symptoms may develop if fumes

from strong acids and alkalis have been inhaled.

Transfer the patient urgently for medical care.

Chemical injury to the eye

– wash the affected eye as quickly as possible

under running tap water or with water from an

eye wash-bottle.

– neutralize with a suitable chemical as follows:

If an acid injury, neutralize with 5% sodium

bicarbonate solution.

If an alkali injury, neutralize with 5% acetic acid

or vinegar diluted 1 in 5.

– immediately seek medical attention.

Emergency treatment for poisoning

Swallowing of an acid or alkali

– immediately rinse the mouth well with water.

– neutralize with a suitable chemical as follows:

If acid has been swallowed, neutralize by drink-

ing 8% w/v magnesium hydroxide suspension

(milk of magnesia) or milk.

If an alkali has b een swallowed, neutralize by

drinking lemon juice or 1% acetic acid.

– drink three or four cups of water.

– seek medical attention.

Note: When an acid or alkali has been swallowed,

do not encourage vomiting.

Swallowing of other poisonous chemicals

– rinse out the mouth well with water.

– depending on the chemical swallowed, take a

suitable chemical antidote under medical super-

vision.

Note: Always seek medical advice and treatment

after swallowing toxic or harmful chemicals.

Swallowing of infected material

– immediately seek medical treatment.

– if required provide follow-up tests.

Mouth-pipetting: This is the main cause of the accidental

swallowing of chemicals or infected material in laboratories.

Further information: Full details of emergency

First Aid measures can be found in the colour pub-

lication:First Aid Manual of St John Ambulance, St

Andrew’s Ambulance Association and Red Cross

(see last entry under Recommended Reading).

REFERENCES

1 Essential medical laboratory services project: Malawi,

Final Report, 2002. Malawi Ministry of Health, Liverpool

School Tropical Medicine, DFID. Obtainable from

HIV/AIDS Dept, Liverpool School Tropical Medicine,

Pembroke Place, Liverpool, L3 5QA, UK.

2 McNerney R. Workplace protection from tuberculosis.

Africa Health, 2002, September, pp. 15–16.

3 Laboratory Biosafety Manual, 3rd edition, 2004. World

Health Organization, Geneva, NHO/CDS/CSR/LYO/

2004.11. Can also be downloaded from the WHO website

www.who.int/csr/resources/publications/biosafety

4 Recommendations on the transport of dangerous goods,

13th revised edition, 2003. New York and Geneva, United

Nations.

5 Transport of infectious substances, 2004. World Health

Organization, Geneva, WHO/CDS/CSR/LYO, 2004. Can

also be downloaded from WHO website www.who.int/csr/

resources/publications

6 Infectious substances shipping guidelines, 2003. Montreal

International Air Transport Association. Can be down-

loaded from website www.iata.org/ads/issg

7 Health Laboratory facilities in emergency and disaster

situations. World Health Organization, 1994 (WHO

Regional Publications Eastern Mediterranean Series, No.

6). Obtainable from WHO Regional Ofﬁce, Abdal

Razzak, AC Sanhouri Street, PO Box 7608, Nasr City,

Cairo 11371, Egypt.

8 Carter J and Lema O. Practical Laboratory Manual for

Health Centres in Eastern Africa, 1994, AMREF, Kenya.

9 Maintenance and repair of laboratory, diagnostic imaging,

and hospital equipment. Geneva, World Health

Organization, 1994.