Résumé
In 1985 a study was undertaken of the prevalence of Trypanosoma cruzi antibodies in 13 departments of Uruguay where transmission of the parasite by the vector Triatoma infestans persists. A total of 5 924 serum samples were selected using a probabilistic method- 3 840 from individuals over the age of 12 (sample I) and 2 084 from subjects who where 12 years old (sample II). The population was classified acording to place of residence (capital city, non-capital city, suburban área, and rural área). The percentage of positive sera detected by indirect immunofluorescence in the different departments ranged from 1 to 11 percent, and overall seroprevalence for the área was 3.4 percent. Based on the results obtained, it was possible to distinguish three áreas: A, which seroprevalence from 6 to 11 percent; B, 2 to 3.2 percent, and C, 1 to 4 percent. In sample II from the Departments of Paysandu, Soriano, Flores, Florida, and Durazno, no cases of Chagas' disease were detected which suggests that there is no active transmission of T. cruzi in this age group in the área studied. The number of persons estimated to have the disease was 36 952, or 1.3 percent of the total population of Uruguay and 4 percent of the population in the área surveyed. These seroprevalence figures are similar to those recorded in the povince of Entre Rios, Argentina, and in the neighboring municipalities of Rio Grande do Sul, Brazil