Chagas" disease (American trypanosomiasis)

Some 90 million people live in the endemic areas. An estimated 16 million people are infected and 27% of them are likely to develop the chronic cardiac phase of the disease. Chagas" disease causes severe incapacitation during peak working years, premature death in the chronic phase, and childhood mortality during the early acute phase. The disease is transmitted by infected triatomine or "kissing bugs", through blood transfusions, or from mother to child during pregnancy. The intensity of infestation by the triatomine vectors is very high in rural areas where housing conditions are poor. Close association of humans to wild and domestic mammals in animal shelters adjacent to houses exacerbates transmission. Socioeconomic advancement is probably as important for control as medicine and vector control. It is possible to control the domestic transmission cycle by indoor house spraying with residual insecticides, but this method is costly and difficult to evaluate because of the extended nature of the infection. Widely applicable chemotherapy is not available because nothing eliminates the intracellular parasites. Current drugs are only effective during the early acute phase and cause gastrointestinal and neurological side effects that require medical supervision. Most Chagas" disease research is being conducted in Latin America and is coordinated by the UNDPWorld BankWHO Special Programme for Research and Training in Tropical Disease (TDR). These efforts are producing results that better clarify geographic differences in pathology and the biology of the parasite. Some improved control methods have been developed, but there has been little success in reducing the intensity of transmission. Contaminated blood bank supplies and infection through transfusion or use of other blood products are increasing problems in Latin America. It is possible to clear the blood of infection, but many places do not have blood banks or facilities to screen and hold the blood for 24 hours for treatment. Studies report contaminated blood levels of 5% to 50% in certain regions. Sale of blood by people migrating to cities from infected areas is an important concern. Major areas for assistance include: improved rural housing, improved blood banks (most likely in association with HIV screening), better diagnosis in early phases when chemotherapy is effective, and more efficient methods of insecticide application. (Author abstract)