[The use of 4 immunological exams for the determination of Chagas disease prevalence in streetsweepers of the City Sanitation Service in the Federal District].

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.