[American trypanosomiasis (Chagas disease) and the nervous system]

Ten to twelve million people irregularly distributed mainly through extensive rural areas of Latin America are afflicted by American trypanosomiasis (Chagas disease). Trypanosoma cruzi is the etiological agent, and it is naturally transmitted to humans by hematophagous hemiptera of Triatominae sub-family. These hemiptera feed by biting and usually defecate in the area near the puncture wound. Mucous membranes of breaks in the continuity of skin serve as passage ways for the parasite present in the excrement of the bug. Acute and chronic forms of American trypanosomiasis occur. Nervous system involvement in the acute form may give rise to meningoencephalitis. Central and/or peripheral signs of nervous system involvement can occur in the chronic form. Neuronal depopulation due to cell destruction by direct parasitism during the acute stage of the disease is the main pathogenetic way pointed out to explain chronic forms of nervous system involvement. Chronic Chagas cardiopathy usually produces mural thrombi. Fragments of thrombus situated in the left ventricle may become detached and migrate with the bloodstream to cause embolic phenomena in distant vessels--as in brain vessels--thus causing embolic cerebrovascular insults. Data on clinical and experimental studies are critically analysed.