Seroprevalence and risk factors of Toxoplasma gondii infection in domestic sika deer (Cervus nippon) in northeastern China

Toxoplasmosis is a worldwide zoonosis caused by Toxoplasma gondii, which can infect warm-blooded animals and humans. A serological survey was undertaken to examine the seroprevalence and risk factors associated with T. gondii infection in sika deer in northeastern China. 114 (13.46%, 95% CI 11.16–15.76) out of 847 serum samples were positive to T. gondii by modified agglutination test (MAT) at a 1:25 cut-off, with titers of 1:25 in 44, 1:50 in 32, 1:100 in 17, 1:500 in 11, 1:1500 or higher in 10. These samples were collected between November 2012 and October 2013 from Inner Mongolia, Jilin and Heilongjiang provinces in China. However, statistically significant differences were not observed between T. gondii seroprevalence and genders or regions of sika deer in the logistic regression analysis (P > 0.05) and left out of the final model. Seroprevalence of T. gondii infection in male sika deer was 14.07% (95% CI 11.14–17.01), slightly higher than that in the female (12.38%) (95% CI 8.69–16.06) and seroprevalence of T. gondii infection in Harbin, Changchun city, Jilin city and Chifeng city were 12.02% (95% CI 7.60–16.44), 15.51% (95% CI 11.52–19.50), 12.27% (95% CI 7.23–17.31) and 12.50% (95% CI 7.38–17.63), respectively. Seasons of sampling were considered as main risk factors associated with T. gondii infection, autumn (15.32%) were more than two times (OR = 1.98, 95% CI = 1.18–3.33, P = 0.01) at risk of acquiring T. gondii infection compared to winter (8.37%). Our results indicated a widespread exposure to T. gondii among sika deer in China. To our knowledge, this is the first report of T. gondii seroprevalence in sika deer in China.