Prevalence of Toxoplasma gondii in chickens from an area in southern Brazil highly endemic to humans

The prevalence of Toxoplasma gondii in free-range chickens from Campos dos Goytacazes, Rio de Janeiro State, Brazil, was examined to evaluate environmental contamination by oocysts. Antibodies against T gondii were assayed by the modified agglutination test (MAT) in sera of chickens. Antibodies against the parasite were found in 129 of 198 chickens with MAT titers greater than or equal to1:25. Brains and hearts of 86 of the 198 chickens were bioassayed in mice for the presence of T. gondii. Viable parasites were isolated from 61 (70.9%) of the 86 chickens. Importantly, viable T. gondii were recovered even from seronegative chickens (MAT titer less than or equal to1:10). The distribution of parasite-positive chickens by MAT titer was 4 of 17 (titer less than or equal to1:10), 3 of 4 (titer of 1: 20), 2 of 6 (titer of 1:40), and 52 of 59 (titer greater than or equal to1:80). Thus, the high recovery rate of T. gondii observed in mice is indicative of high levels of environmental contamination of free-range chickens by T. gondii oocysts in this area that is endemic to humans.