Autonomic neuropathy and immunological abnormalities in Chagas' disease

Chagas' disease (American Trypanosomiasis) is caused by infection with the haemoflagellate parasite Trypanosoma cruzi, which is transmitted from animals to man by the Reduviidae bug. The human disease is characterized by two phases. In the first (acute phase) parasitaemia is high and general symptoms variable. The next, which is lifelong (chronic phase), is characterized by inflammatory lesions in cardiac and skeletal muscle, gastrointestinal, the autonomic nervous system. Parasites are difficult to detect in blood and affected tissues. Lesions within the autonomic nervous system, lead to development of cardiomyopathy, megaoesophagus and megacolon. The discrepancy between the profusion of inflammatory lesions and the absence of parasites suggests the development of autoimmunity probably of a cell-mediated type. Several autoimmune abnormalities have been noted during Trypanosoma cruzi infection. These include suppression of the specific response to autoantibodies directed against antigens located in the endocardium and in nerves, and development of cell-mediated immunity against host antigens (cytotoxic T- and delayed type hypersensitivity T-cells). These autoimmune disorders are thought to be responsible for much of the pathological damage in chronic Chagas' disease.