Chagas' disease: lessons from routine donation testing.

American Trypanosomiasis, or Chagas' disease, is a parasitic infection caused by the protozoan Trypanosoma cruzi. It is endemic in a large area of the American continent, extending from Mexico to Argentina. Imported Chagas' disease is now appearing as a new threat to non-endemic countries, mostly because of a steady increase of foreign residents from Latin America. Chagas' disease becomes chronic in the vast majority of infected individuals. This finding gives rise to problems for blood transfusion services. In non-endemic countries, transfusion is the most likely infection route. Strategies to reduce transmission by transfusion include blood donor selection and deferral, blood donation testing, leukoreduction, filters and pathogen inactivation systems. Policies in endemic and non-endemic areas are quite different: in endemic countries, universal screening of blood donations for T. cruzi antibody detection is mandatory. However, in non-endemic countries, there are two different approaches: one is the deferral of people at risk of Chagas' disease and the second approach is to accept the blood donation if specific laboratory assay results are negative. This second approach is being introduced in countries where there is a substantial Latin American population, such as United States, Spain and France. The assays used for the detection of T. cruzi are mostly immunologic, made with T. cruzi antigen homogenates or with recombinant antigens. Complementary assays, such as indirect immunofluorescence (IIF) or immunoblot, can help ascertain antibody specificity.