WHO Technical Report Series 905 CONTROL OF CHAGAS DISEASE A Second report of the WHO Expert Committee aA World Health Organization Geneva i COC Cover1 1 2/16/02, 9:18 AM The World Health Organization was established in 1948 as a specialized agency of the United Nations serving as the directing and coordinating authority for international health matters and public health. One of WHO’s constitutional func- tions is to provide objective and reliable information and advice in the field of human health, a responsibility that it fulfils in part through its extensive programme of publications. The Organization seeks through its publications to support national health strat- egies and address the most pressing public health concerns of populations around the world. 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An annual subscription to this series, comprising about 10 such reports, costs Sw. fr. 132.– (Sw. fr. 92.40 in developing countries). ii COC Cover2 2 2/16/02, 9:19 AM This report contains the collective views of an international group of experts and does not necessarily represent the decisions or the stated policy of the World Health Organization WHO Technical Report Series 905 CONTROL OF CHAGAS DISEASE Second report of the WHO Expert Committee World Health Organization Geneva 2002 i COC PR 1 2/16/02, 9:26 AM WHO Library Cataloguing-in-Publication Data WHO Expert Committee on the Control of Chagas Disease (2000 : Brasilia, Brazil) Control of Chagas disease : second report of the WHO expert committee. (WHO technical report series ; 905) 1.Chagas disease — prevention and control 2.Chagas disease — transmission 3.Trypanosoma cruzi 4.Disease vectors 5.Guidelines I.Title II.Series ISBN 92 4 120905 4 (NLM classification : WC 705) ISSN 0512-3054 The World Health Organization welcomes requests for permission to reproduce or translate its publica- tions, in part or in full. Applications and enquiries should be addressed to the Office of Publications, World Health Organization, Geneva, Switzerland, which will be glad to provide the latest information on any changes made to the text, plans for new editions, and reprints and translations already available. © World Health Organization 2002 Publications of the World Health Organization enjoy copyright protection in accordance with the provisions of Protocol 2 of the Universal Copyright Convention. All rights reserved. The designations employed and the presentation of the material in this publication do not imply the expression of any opinion whatsoever on the part of the Secretariat of the World Health Organization concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. The mention of specific companies or of certain manufacturers’ products does not imply that they are endorsed or recommended by the World Health Organization in preference to others of a similar nature that are not mentioned. Errors and omissions excepted, the names of proprietary products are distin- guished by initial capital letters. Typeset in Hong Kong Printed in Singapore 2001/13948 — SNPBest-set/SNPSprint — 7500 ii COC PR 2 2/16/02, 9:26 AM Contents 1. Introduction 1 2. Basic information on Chagas disease 2 2.1 Clinical forms 2 2.1.1 Acute phase 2 2.1.2 Chronic phase 5 2.2 Pathology 17 2.2.1 Acute phase 17 2.2.2 Chronic phase: heart pathology 18 2.2.3 Chronic phase: digestive form 21 2.2.4 Chagas disease and AIDS 21 2.2.5 Pathogenesis of chronic lesions 22 2.3 Laboratory diagnosis 24 2.3.1 Parasitological diagnosis 24 2.3.2 Immunodiagnosis 25 2.4 Clinical management and treatment 29 2.4.1 Trypanosomicidal treatment 29 2.4.2 Drug development 29 2.4.3 Acute phase 32 2.4.4 Chronic phase 33 2.4.5 Assessment of cure 35 3. Parasitology 35 3.1 Taxonomy 35 3.2 Isolation and maintenance of T. cruzi strains 35 3.3 Biological characteristics 35 3.4 Genetic characteristics 37 3.5 The parasite genome and the T. cruzi genome project 39 4. Vectors 40 4.1 Taxonomy 40 4.2 Geographical distribution 41 4.3 Biology 43 4.4 Ecology and behaviour of triatomines 46 4.4.1 Species strictly domiciliated or exceptionally found in wild ecotopes 47 4.4.2 Species found in both domestic and wild ecotopes, with frequent domiciliated colonies 47 4.4.3 Species mainly wild, but sometimes captured in the domestic environment 49 4.4.4 Wild species, with adults seldom found in dwellings 49 4.4.5 Species found only in wild ecotopes 49 4.5 Climatic factors and dispersion and adaptation of triatomines 49 4.5.1 Sylvatic ecotopes and the domiciliation process 50 4.5.2 The changes associated with domiciliation 51 4.6 Population genetics 52 4.7 Epidemiological application of the new tools 52 4.7.1 Systematics 53 iii COC PR 3 2/16/02, 9:26 AM 4.7.2 Population structure 53 4.7.3 Population movements and reinfestation 54 4.7.4 Historical population movements 55 5. Natural reservoirs 55 5.1 Domestic and synanthropic reservoirs 56 5.2 Wild reservoirs 57 5.3 Importance of birds and other terrestrial vertebrates 58 6. Epidemiology and incidence trends 59 6.1 Modes of transmission and ecological factors 59 6.1.1 Transmission by vectors 59 6.1.2 Transmission by blood transfusion 59 6.1.3 Congenital transmission 60 6.1.4 Transmission by organ transplantation 60 6.1.5 Accidental transmission 61 6.1.6 Oral transmission 61 6.1.7 Ecological factors 61 6.1.8 Anthropogenic environmental changes 62 6.2 Prevalence and geographical distribution of the disease 63 6.3 Epidemiological trends and changes in the period 1983–2000 68 7. Prevention and control 69 7.1 Chemical control 70 7.1.1 Introduced and native species 71 7.1.2 Inputs and equipment 73 7.1.3 Programme organization 73 7.2 Physical control 74 7.3 Health education and community participation 76 7.4 Improvement of living conditions 76 7.5 Programme implementation in the context of primary health care 77 7.6 Evaluation of vector resistance to insecticides 77 7.6.1 Laboratory bioassays 78 7.6.2 Insecticidal effect of formulations 78 7.6.3 Resistance and tolerance 79 8. Subregional initiatives for the interruption of transmission 80 8.1 Southern Cone Initiative 80 8.1.1 Situation analysis 80 8.1.2 The formal decision 81 8.1.3 Strategies and methods 81 8.1.4 Intercountry mechanisms 82 8.1.5 Resources 84 8.1.6 Results 84 8.1.7 Overall impact of the Initiative in the region 85 8.1.8 Cost–effectiveness studies in Brazil 86 8.2 Andean Initiative 86 8.2.1 Andean Pact agreement 86 8.2.2 Situation analysis 87 8.3 Central American Initiative 88 8.3.1 Central American agreement 88 8.3.2 Situation analysis 88 iv COC PR 4 2/16/02, 9:26 AM 9. Development of human resources 89 10. Research priorities 90 10.1 Clinical pathology and diagnostic tests 90 10.1.1 Clinical pathology 90 10.1.2 Diagnostic tests 90 10.1.3 New tools for use in evaluating vector control 90 10.2 Biochemistry, functional genomics, and drug development 91 10.3 Social and economic research 91 11. Recommendations 91 Acknowledgements 92 References 93 Annex 1 Safety precautions for laboratory work with Trypanosoma cruzi 100 Annex 2 Labelling of Trypanosoma cruzi isolates 102 Annex 3 List of sylvatic and domestic or peridomestic animal reservoir hosts of Trypanosoma cruzi and countries in which they have been found infected 106 v COC PR 5 2/16/02, 9:26 AM WHO Expert Committee on the Control of Chagas Disease Brasilia, 20–28 November 2000 Members Dr J.R. Coura, Director, Oswaldo Cruz Institute (FIOCRUZ), Rio de Janeiro, Brazil (Chairman) Dr J.C.P. Dias, René Rachou Research Centre, Belo Horizonte, Brazil Dr A.C.C.