Immunological and clinical evaluation of chagasic patients subjected to chemotherapy during the acute phase of Trypanosoma cruzi infection 14-30 years ago

We recently evaluated the in vitro proliferative response and interferon (IFN)-gamma production of peripheral blood mononuclear cells from a group of 25 people who were treated for Chagas' disease during the acute phase of Trypanosoma cruzi infection and followed up for a period of 14-30 years. On the basis of the parasitological and serological tests, the individuals were classified as cured (C), dissociated, or not cured (NC). Members of group C (the group without cardiac alterations) presented significantly stronger proliferative response against the parasite antigens, with secretion of high levels of IFN-gamma in comparison with the NC group, raising a question about the role of this cytokine in the curing of human T. cruzi infection. Severe cardiac alterations were observed only in 1 of 25 patients, which suggests that treatment benefited the patients.

IFN-gamma in human Chagas' disease: protection or pathology?

An apparently paradoxical role for IFN-gamma in human Chagas' disease was observed when studying the pattern of cytokine production by peripheral blood mononuclear cells (PBMC) obtained from two groups of chagasic patients after specific stimulation with Trypanosoma cruzi-derived antigens. The groups studied were 1) patients treated with benznidazole during the acute phase of Trypanosoma cruzi infection and 2) chronically infected untreated patients. In the treated group, higher levels of IFN-gamma were produced by PBMC from individuals cured after treatment when compared to non-cured patients. In contrast, in the chronically infected group (not treated) higher levels of IFN-gamma were produced by PBMC from cardiac patients in comparison with asymptomatic (indeterminate) patients. This apparently paradoxical role for IFN-gamma in human Chagas' disease is discussed in terms of the possibility of a temporal difference in IFN-gamma production during the initial stages of the infection (acute phase) in the presence or absence of chemotherapy. The maintenance of an immune response with high levels of IFN-gamma production during the chronic phase of the infection may favor cure or influence the development of the cardiac form of the disease.

[Hemoculture: sensitive technique in the detection of Trypanosoma cruzi in chagasic patients in the chronic phase of Chagas disease]

The sensitivity of hemocultures, performed once or three times, was investigated in 52 patients in the chronic phase of Chagas disease. Modifications were introduced in the technique such as, processing the blood more rapidly, gently homogenizing the cultures and examining them after 120 days of culture. Our results show a high percent age of positivity i.e. 79% and 94% of patients submitted, respectively, to one or three tests. No significant differences related to the patients age were detected, which varied from 14 to 82 years old. Our results demonstrate that hemoculture is a sensitive method for the parasitological diagnosis of Chagas disease and is ideal for monitoring cure in treated patients.