[Chronic tissue lesions in white mice immunized and infected with Trypanosoma cruzi]

Mice were immunized with whole membranes of cultured epimastigotes and then inoculated with cultured trypomastigotes. The blood parasite count was lower than in the control. No changes could be detected however, in the length of the prepatent period nor in the extent and duration of the tissue damage observed in the chronic phase of the infection. Damage was evident in the tissues of both immunized and naive animals up to 171 days post inoculum. Blood parasites could be demonstrated neither by direct observation nor by culture, as soon as 117 days after infection. The presence of mast cells a few hours after infection and throughout the study suggests a role of these cells in both the specific and nonspecific components of host response.