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In this study, we isolated Trypanosoma cruzi from chronic Chagas heart disease and from megaesophagus patients. The parasite stock hSLU239 (heart disease) yielded clones h1 and h2, whereas stock mSEU142 (megaesophagus) yielded clones m1, m2, m3 and m4. The parasite growth kinetics, doubling time and differentiation in axenic liquid medium showed broad behavioral diversity. It was shown that a particular pattern of behavior for a parental stock could not necessarily be assigned for subsequent clones. This study indicates that i) each Chagas disease patient is infected with several T. cruzi populations; ii) clonal lines derived from patient samples may have different biological characteristics from the original isolate; and that iii) additional behavioral and/or molecular markers are required for further characterization of Trypanosoma cruzi stocks and clones derived from Chagas disease patients in order to identify correlations with pathology.

Seropositivity for Trypanosoma cruzi infection was studied in 368 street-sweepers of the SLU, Federal District, Brazil, with the aid of haemaglutination, immunofluorescence and, also, a delayed-type skin test to the parasite T12E antigen. It showed 32.1%, 42.1% and 38.6% positive results, respectively for each assay. Among these, however, only 47% were positive with each of three exams performed. In addition, 19.7% were positive with two out of three exams performed. The remaining 33.3% sera yielded one positive result out of three exams employed and were submitted to the immunoblot assay. This analysis confirmed 3 cases (37.5%) positive by hemmaglutination, 3 (11.5%) positive by skin test, and 1 (3.7%) positive by immunofluorescence. At the end of the analysis, it was shown that 129 (35%) individuals yielded at least two positive assays and, therefore, they should be considered as T. cruzi-infected individuals.