District Laboratory Practice in Tropical Countries Part 1, Second Edition

462 Pages·2009·6.45 MB·English

by  Monica Cheesbrough

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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
Published in the United States of America by Cambridge University Press, New York
www.cambridge.org
Information on this title: www.cambridge.org/9780521676304
© Monica Cheesbrough 1998, 2005, 2009
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.
First published in print format 2005
ISBN-13 978-0-511-34935-5 eBook (NetLibrary)
ISBN-13 978-0-521-67630-4 paperback
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.
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
because 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.
Part I
Contents
Chapter 1 Organization and staffing of district laboratory services
1.1 Importance of laboratory practice in district health care. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pages 1– 3
1.2 Structuring of a district laboratory network. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3– 9
1.3 Training and continuing education of district laboratory personnel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10–11
1.4 Code of conduct for laboratory personnel and status of medical laboratory practice. . . . . . . . . . . . . . . . . . 11–12
Chapter 2 Total quality management of district laboratory services
2.1 Ensuring a reliable and quality laboratory service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14–20
2.2 Selection of tests and interpretation of test results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20–28
2.3 Financing district laboratory services and controlling costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28–31
2.4 Quality assurance and sources of error in district laboratory practice. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31–37
2.5 SIUnits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37–40
2.6 Guidelines for preparing stains and reagents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40–47
2.7 Communicating effectively. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47–48
Chapter 3 Health and safety in district laboratories
3.1 Implementing a laboratory health and safety programme. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50–56
3.2 Safe laboratory premise and personal safety measures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56–59
3.3 Microbial hazards. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59–66
3.4 Decontamination of infectious material and disposal of laboratory waste. . . . . . . . . . . . . . . . . . . . . . . . . . . . 66–74
3.5 Chemical and reagent hazards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75–87
3.6 Equipment and glassware hazards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87–89
3.7 Fire safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89–91
3.8 Emergency First Aid. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91–95
Chapter 4 Equipping district laboratories
4.1 Selection, procurement and care of equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96–103
4.2 Power supplies in district laboratories. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103–108
4.3 Microscope. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109–126
4.4 Equipment for purifying water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 –131
4.5 Equipment for weighing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132–133
4.6 Equipment for pipetting and dispensing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134–138
4.7 Centrifuges. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139–143
4.8 Laboratory autoclave. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143–148
4.9 Incubator, water bath, heat block. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148–152
4.10 Colorimeter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152–157
4.11 Mixers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158–160
4.12 General laboratory-ware for district laboratories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160 –175
Chapter 5 Parasitological tests
5.1 Parasitology in district laboratories and quality assurance of tests. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178 –183
5.2 Features and classification of parasites of medical importance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 –191
5.3 Direct examination of faeces and concentration techniques. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191–200
5.4 Identification of faecal protozoan trophozoites, cysts and oocysts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200–208
iii
5.5 Identification of helminth eggs and larvae found in faeces. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209–235
5.6 Examination of urine for Schistosoma haematobiumeggs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236–239
5.7 Examination of blood for malaria parasites. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239–258
5.8 Examination of blood, lymph fluid, and c.s.f for trypanosomes causing African trypanosomiasis. . . . . . . 259–266
5.9 Examination of blood for Trypanosoma cruzi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266–271
5.10 Examination of specimens for Leishmaniaparasites. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271–279
5.11 Examination of blood for microfilariae in lymphatic filariasis and loiasis. . . . . . . . . . . . . . . . . . . . . . . . . . . 280–291
5.12 Examination of skin for Onchocerca volvulusmicrofilariae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291–295
5.13 Examination of sputum for Paragonimuseggs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295–297
5.14 Less frequently needed tests:
1 Investigation of amoebic liver abscess . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 298–299
2 Investigation of primary amoebic meningoencephalitis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299–300
3 Diagnosis of toxoplasmosis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300–302
4 Diagnosis of hydatid disease. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302–304
5 Examination of muscle tissue for Trichinella spiralis larvae. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304–305
6 Detection of Dracunculus medinensis(Guinea worm) larvae. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305–306
Chapter 6 Clinical chemistry tests
6.1 Clinical chemistry in district laboratories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310–313
6.2 Quality assurance of clinical chemistry tests. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313–333
6.3 Measurement of serum or plasma creatinine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333–337
6.4 Measurement of serum or plasma urea. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337–340
6.5 Measurement of blood or plasma glucose. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 340–349
6.6 Measurement of serum or plasma bilirubin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 349–355
6.7 Measurement of serum albumin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355–358
6.8 Measurement of serum or plasma alanine aminotransferase (ALT)activity . . . . . . . . . . . . . . . . . . . . . . . . 358–361
6.9 Measurement of serum or plasma alphaamylase activity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 360–364
6.10 Measurement of sodium and potassium in serum or plasma. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 364–369
6.11 Urine tests. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 369–385
6.12 Cerebrospinal fluid (c.s.f) tests. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 386–389
6.13 Faecal 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
v
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.
vi
ORGANIZATION AND STAFFING OF DISTRICT LABORATORY SERVICES 1
1
Organization and staffing of district
laboratory services
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.1
Meaning of district as used in this manual Plate 1.1 Typical community-based district hospital in Kenya.
The district is designated by the World Health Organization
as the key level for the management, growth and consoli- The growth of district health systems has led to:
dation of primary health care (PHC). It is the most
peripheral unit of local government and administration that – essential health services and health decisions
has comprehensive powers and responsibilities. being brought closer to where people live and
work.
A typical rural district health system consists of:
– communities becoming more aware of health
(cid:1) A network of PHC facilities, including village issues and demanding health services that are
health clinics, maternity centres, health centres relevant, accessible, reliable, affordable, and
and small urban clinics. Mobile health units may accountable.
also provide some outreach PHC services and – district health councils being formed to identify
support for home-based health care. and assess community health care needs,
(cid:1) A system for the referral of seriously ill patients develop and manage local health services, and
ensure district health resources are used
needing specialist care.
effectively, efficiently and equitably.
(cid:1) The district hospital (first referral hospital).
(cid:1) Other government health related departments,
including social and rehabilitative services,
environmental health, nutrition, agriculture,
water supply and sanitation.
(cid:1) 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
Plate 1.2 Health centre in Vietnam.
departments such as water and sanitation. Courtesy: RP Marchand, MCNV.
1.1
2 DISTRICT LABORATORY PRACTICE IN TROPICAL COUNTRIES
WHY THE LABORATORY IS NEEDED IN DISTRICT (cid:1) The laboratory is needed to work with others in
HEALTH CARE reducing infection in the community and investi-
gating epidemics rapidly
The laboratory has an important role in improving
the:
● quality, The public health functions of a district health
laboratory service include:
● efficiency,
● cost-effectiveness, – detecting the source(s) of infection, identifying
carriers, and contact tracing.
● planning and management of district health care.
– participating in epidemiological surveys.
– assisting in disease surveillance and in the selec-
What difference can the laboratory make to
tion, application, and evaluation of control
the quality of district health care?
methods.
(cid:1) Laboratory investigations increase the accuracy of – helping to control hospital acquired infections.
disease diagnosis – participating in health education.
Many infectious diseases and serious illnesses can – examining designated community water supplies
only be diagnosed reliably by using the laboratory. for indicators of faecal and chemical pollution.
For example, errors in the diagnosis of malaria have – responding rapidly when an epidemic occurs,
been shown to be particularly high when diagnosis including appropriate on-site testing and the
is based on clinical symptoms alone. collection and despatch of specimens to the
Regional or Central Microbiology Laboratory for
Misdiagnosis or late diagnosis can lead to:
pathogen identification.
– incorrect treatment with misuse and waste of
drugs. In what ways can the laboratory contribute to
– increased morbidity and mortality. achieving efficiency and cost effectiveness in
– hospitalization and need for specialist care. district health care?
– patient dissatisfaction leading to negative
responses to future health interventions. (cid:1) The laboratory can help to reduce expenditure on
– underutilization of health facilities. drugs
– lack of confidence and motivation of health When the laboratory is used to improve the accu-
personnel. racy of diagnosis, perform appropriate antimicrobial
– increased risk to the community from inappro- susceptibility testing, and monitor a patient’s
priate disease management and untreated response to treatment:
infectious disease.
– drugs can be used more selectively and only
(cid:1) The laboratory has an essential role in screening when needed.
for ill health and assessing response to treatment – patterns of emerging drug resistance can be
identified more rapidly and monitored.
At district level the laboratory is needed to:
– assess a patient’s response to drug therapy. (cid:1) The laboratory can lower health care costs by
– assist in monitoring the condition of a patient identifying disease at an early stage
and help to decide when it may be necessary to Early successful treatment following early correct
refer for specialist care. laboratory diagnosis can help to:
– screen pregnant women for anaemia, protein-
uria, and infections which if not treated may – reduce the number of times a patient may need
cause disease in the newborn, premature birth, to seek medical care for the same illness.
low birth weight, or significant maternal illness. – prevent complications arising from advanced
– screen the contacts of persons with infectious untreated disease.
diseases such as tuberculosis and sexually trans- – avoid hospitalization and further costly investi-
mitted diseases. gations.
– detect inherited abnormalities such as haemo-
(cid:1) Significant savings can be made when the labora-
globin S as part of district family planning health
tory participates in local disease surveillance and
services.
control
– screen whole blood and blood products for
transfusion transmitted pathogens. This is because:
1.1