American trypanosomiasis: Chagas' disease

Abstract

American trypanosomiasis, or Chagas' disease, is a major public health problem in America. More than seven million people are infected, according to WHO estimates. Nearly twenty million people are at risk of contracting this disease. The number of people who later develop the chronic and fatal form of the disease is unknown, but it is estimated that 10% of those infected with T. cruzi develop chronic Chagas' disease. Our observations regarding the isolation of a common antigenic principle in T. cruzi and the myocardium may provide the basis for therapy by immunologic manipulation of patients with chronic Chagas' disease. Before instituting any therapeutic approach, the relationship of common immunogens of T. cruzi target organs and the major histocompatibility complex must be firmly established. This approach has been selected because any consideration of immunologic control of this disease requires clear differentiation of which antigens enhance tissue damage and which may control parasitemia. T. cruzi particulate antigens lead to delayed hypersensitivity, and this is the major immunopathologic mechanism involved in the development of chronic Chagas' disease. On the other hand, the T. cruzi cytosol appears to be related principally to the production of complement-fixing antibodies and hemagglutinins probably important in the clearance of parasites by macrophages and, to a lesser extent, immune lysis of the emerging extracellular forms of the parasite. One then may be able to manipulate these antigens to favor prevention of parasitemia.