Neuropathy associated with experimental Chagas' disease.

Mice were acutely and chronically infected with Trypanosoma cruzi and then examined histologically for the presence of lesions in the peripheral nervous system. In acutely infected animals, small lymphocytic and macrophagic infiltrates were found in the nerves in association with intracellular parasites. Little or no nerve damage was present at this stage. In chronically infected animals, large perivascular granulomatous infiltrates were found in association with multifocal, predominantly demyelinative lesions of neighboring nerve fibers. Similar inflammatory infiltrates were present in muscles and were frequently associated with vasculitis and destruction of muscle fibers. Our pathological findings and the negative results produced by intraneural injections of sera from chronically infected animals and the positive results following injections of small numbers of live trypanosomes suggest that the demyelination is not due to circulating serum factors such as antibodies cross-reacting with peripheral myelin. Delayed-type hypersensitivity may be induced by the presence of the parasites, a notion supported by the development of granulomas in naive mice injected intravenously with helper T cells from chronically infected animals.