First serologic survey of Q fever in free-range yaks in China

The objective of the present investigation was to determine the seroprevalence of Coxiella burnetii infection in free-range yaks in China. A total of 552 serum samples were collected from yaks in Gansu province، northwest China between April 2013 and January 2014، and antibodies against C. burnetii were evaluated using enzyme-linked immunosorbent assay (ELISA). Overall، 13. 59% (75/552، 95% CI: 10. 73-16. 45) of the examined animals were positive for C. burnetii antibodies. There was no significant difference in C. burnetii seroprevalence between female yaks (13. 78%، 95% CI: 10. 36-17. 19) and male yaks (13. 13%، 95% CI: 7. 89-18. 36) (P>0. 05). Coxiella burnetii seroprevalence in yaks in different age groups ranged from 10. 88% to 15. 26%، but the difference was not statistically significant (P>0. 05). Coxiella burnetii seroprevalence in yaks sampled in different seasons ranged from 12. 06% (autumn) to 18. 33% (summer)، but the difference was not statistically significant (P>0. 05). This is the first report of C. burnetii seroprevalence in free-range yaks in China، indicating the need for measures to be taken to control C. burnetii infection in free-range yaks in China.