ARS | Publication request: Prevalence of Toxoplasma Gondii in Chickens from a Highly Endemic Area to Humans in Southern Brazil

Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 30, 2002
Publication Date: January 30, 2003
Citation: Seipel Da Silva Azer, D., Bahia-Oliveira, L.M., Shen, S.K., Kwok, O.C., Lehman, T., Dubey, J.P. 2003. Prevalence of toxoplasma gondii in chickens from a highly endemic area to humans in southern brazil. Journal of Parasitology 89:394-396.

Interpretive Summary: Toxoplasma gondii is a single celled parasite of livestock and humans. It causes mental retardation and loss of vision in congenitally infected children and abortion in livestock. Toxoplasmosis is a ubiquitous infection acquired by the ingestion of food or water contaminated with oocysts excreted by infected cats. Given that, T. gondii contaminated soil is likely to be a continuous source of infection for animals and humans and the prevalence of T. gondii in naturally-infected feral chickens may be considered as an indicator of the presence of T. gondii oocysts in the environment due to the geophagic eating habits of these animals chickens from a rural area outside Rio de Janeiro, Brazil were examined for T. gondii infection by scientists at the Beltsville Agricultural Research Center. Toxoplasma was isolated from tissues of 71% of chickens examined. These results will be of interest to biologists, parasitologists and public health workers.

Technical Abstract: 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 to 1:25. Brains and hearts of 86 of 198 chickens were bioassayed in mice for the presence of T. gondii. Viable parasites were isolated from 61 (70.9%) of 86 chickens. Importantly, viable T. gondii were recovered even from seronegative chickens (MAT less than or equal to 1:10). The distribution of parasite-positive chickens by MAT titer was: 4 of 17 (titer less than or equal to 1:10), 3 of 4 (titer 1:20), 2 of 6 (titer 1:40), and 52 of 59 (titer of 1:80). Thus, the high recovery rate of T. gondii observed in mice is indicative of high levels of environmental contamination of free-range chickens with T. gondii oocysts in this endemic area to humans.