Chagas disease or American trypanosomiasis.

3. Parasitic diseases Chagas disease or American trypanosomiasis* 1. Brief description of the condition/disease Chagas disease. also known as American trypano- somiasis, is caused by the parasitic protozoan Trypatnosoma cruZz and is transmitted primarily by triatonune insects; it can also be transmitited by blood transfusion. Neither an effective vaccine nor therapy is available. In approximately 30% of cascs, chronic. often severe and life-threatening cardiac or digestive tract disease occurs 20-30 years after initial infection. 2. Current global burden and rating within the overall burden of disease The disease is believed to affect 16-18 million peo- ple. primarily in Central and Soutlh America; an esti- mated 100 million people are at risk, accounting tor approximately 25% ot the entire population of this region. Chagas disease accounts for an estimated 45 O0() deaths eachi year and is ranked third behind malaria and scbistosomiasis by WHO in terms of global burden as a tropical disease. 3. Feasibility (biological) of elimination/eradication WHO has targeted elimination of domestic transmis- sion of Chagas disease. Because it exists as a zoonosis. complete eradication is JIot fcasiblc; however, conLrol of human transmission is consid- ered achievable by eliminating domestic insect vec- tor populalions. 4. Estimated costs and benefits of elimination/eradication Early estimates suggested that effective control could result in medical and economic benefits ex- * Contributed by C Ben Beard, Centers for Disease Control and Prevention, Atlanta, GA, USA and Chris J. Scholield London School o1 Hygiene and Tropical Medicine, London, England, Ihe ECLAT network, and World Health Organizabon, Geneva, Switzerland ceeding US$ 53 mllion per year, in the Sonthern Cone conutries alone. compared with an estimated total cost ot US$ 190-350 million lor the 10-year programme. More recent (1997) estimnates suggest that the overall benefits of disease eliminiation could exceed US$ 3500 million per year. 5. Key strategies to accomplish the objective(s) Elimination efforts tocus on domiciliarv insecticide applications using residual pvrethroids. improve- ment of hiousing conditions, and blood bank surveillance. 6. Research needs Research needs include studies of vector population biology and genetics, evaluation of the impact of current vector-control programmes, tools ior more effective blood banik screening, new etfective drugs [or treatment, and studies on immunopathogenesis. 7. Status of elimination/eradication efforts to date Through the efforts of thc Southlern Cone Initiative, the chief regional vector Triatonut infestans has been virtually eliminated from niost of Uruguay and Chile, from much of its orignal distribution in Brazil and Argentina, and from regions of Paraguay and southern Bolivia. resultLng in effective interrUp- tioln ot disease transmission m these countries. A 70%/1) reduction of incidence of T. cnizi infectioII in young age groups has been achieved between 1985 and 1997. 8. Principal challenges to elimination/eradication Effectivc coordtnation. thoroughness. and long-tenn sustainability of vector control ettorts are the pri- mary challenges to elmiination efforts. 144 Bulletin of the Wordk Health Organizaton, 1998 76 (Suppf 2) 144