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Beginning the study of chronic pathologic changes in pancreas of hamsters experimentally infected with Trypanosoma cruzi Vic strain, hepatocyte metaplasia was observed in one animal from infected group. This is the first report of oncocytes in Chagas' disease, which could be due to aberrant regenerative response to pancreas inflammatory process.

From this present data it has been evaluated a new complement fixation test, comparatively to indirect immunofluorescence to diagnose chronic Chagas' disease, utilizing one watery extract of epimastigotes of Trypanosoma cruzi and three other ethanolic extracts: one from epimastigotes, one from tripomastigotes and a third one of amastigotes obtained from cultures. Utilizing 236 serum samples indirect immunofluorescence test was performed: 109 positives (20 of them with positive parasitologic diagnostic) and 127 negatives (96 of healthy blood donors and 31 with other diseases). The results have showed that is possible a positive reaction in diluted samples up to 1:16. The best limits of reactivity found were the dilutions 1:4 for the ethanolic extract of amastigotes and 1:2 for the others antigens. The correlation index among the new complement fixation test and indirect immunofluorescence test showed that the ethanolic extract from epimastigotes was the best antigen to be utilized to diagnosis purposes. Its co-positivity index with indirect immunofluorescence was 0.92207 and the co-negative index was 0.90000. Concluding, the new complement fixation test showed itself as a fast, sensible, easily applicable semiquantitative microtechnique to the diagnosis of chronic Chagas' disease.

This data evaluated the susceptibility of T. infestans to seven different strains of T. cruzi from chagasic patients of the Triângulo Mineiro, isolated and adapted in Swiss mice. A total of 200 bugs were fed in mice in acute phase injected with the different strains of T. cruzi and at each 30 days, during 5 months, their feces were obtained by abdominal compression or spontaneous dejection. The overall positivity of T. infestans infection with these different strains of T. cruzi was 62.08%. There was a high mortality rate (60%) during the examination period. We conclude that T. infestans has a low susceptibility to these strains. This could explain the low rate of positivity in the xenodiagnosis in chagasic chronic patients of the Triângulo Minerio.

This research characterizes the acute and chronic phases of Chagas' disease in hamster through parasitological and histopathological studies. The acute phase was achieved with 44 young hamsters injected intraperitoneally with 100,000 blood trypomastigotes of Benedito and Y strains of T. cruzi. The chronic phase was induced in 46 hamsters injected intraperitoneally with 35,000 trypomastigotes of Vicentia, Benedito and Y strains. Animals were sacrificed at regular intervals of 24 hours of acute phase and from the 3rd to the 10th month of infection of chronic phase. In the acute phase, parasites were easily recovered from all animals and there was an inflammatory reaction characterized by mononuclear and polymorphous leukocyte infiltration of variable degree in the majority of tissues and organs, specially in the connective loose and fatty tissues, smooth muscle myocardium and skeletal muscle. In the chronic phase the lesions occurred in the same tissues and organs, but the inflammatory response was less severe and characterized by mononuclear infiltration mainly with focal or zonal fibrosis in the myocardium. In 50% of infected animals parasites were found in myocardium and recovered from pericardic, peritoneal and ascitic fluids in some animals. Signs of heart failure, sudden death and enlargement of bowel were observed regularly. We concluded that the hamster is an useful model for Chagas' disease studies.