Seroprevalence, Risk Factors, and Genotypes of Toxoplasma gondii in Free-Range Chickens Intended for Human Consumption in China

Toxoplasma gondii is a protozoan with worldwide distribution that infects birds and mammals, including humans. The consumption of free-range chicken meat is a common practice in many parts of the world. However, little information is available concerning the molecular prevalence and genotypes of T. gondii infection in free-range chickens intended for human consumption in China. In this study, a total of 1360 serum samples were collected from food markets in Hunan province of China for detecting T. gondii antibodies by indirect hemagglutination assay. In addition, 650 brain tissues were also collected to investigate T. gondii DNA by amplification of B1 gene with a seminested polymerase chain reaction (PCR), and the positive DNA samples were typed at 10 genetic markers using multilocus PCR-restriction fragment length polymorphism. Antibodies to T. gondii were detected in 457 of the examined serum samples (33.6%; 95% confidence interval [CI]: 31.1-36.1), and 72 DNA samples (11.1%; 95% CI: 8.6-13.4) were positive for the T. gondii B1 gene. In this study, region and age of free-range chickens were shown to be risk factors for T. gondii infection (p < 0.01). Two genotypes (ToxoDB#9 and ToxoDB#52) were identified from two samples with complete genotyping results. Our study revealed a high prevalence of T. gondii infection in free-range chickens intended for human consumption in Hunan province, suggesting that recommendations to consumers should be made, especially in some regions of China where consumption of undercooked chicken meat is common. This is the first genetic characterization of T. gondii in free-range chickens intended for human consumption in Hunan province, China, and also the first report of genotype ToxoDB#52 in China.