Aspects Seroepidemiological Studies On Q Fever In Unvaccinated Dairy Cattle Herds

Q fever is a zoonosis distributed worldwide and important in human as well as in veterinary medicine in Germany. In Baden-Wurttemberg, the pathogen is endemic. Usually Q fever is associated with infected sheep flocks. In contrast, however, in the animal disease reporting system (TSN) 88.1% of all listed Q fever infections during the last 12 years have been registered in cattle. Accordingly, in Baden-Wurttemberg and Freudenstadt 78.3 and, respectively, 62.5% of the Q fever cases were from cattle. Long term studies on appearance of Coxiella burnetii in normal herds of cattle are missing. Increasing vaccination of cattle herds against Q fever with the vaccine approved in Germany (no marker vaccine) complicates the future opportunities to gain data from serological studies. In the present study, a total of 1640 bovine sera taken from unvaccinated, clinically insignificant cattle from Freudenstadt in Baden-Wurttemberg were tested serologically on individual animal basis. Sera were taken over a period of 3 years (2009-2011) and examined using three different assays for antibody determination against C. burnetii for analysis and comparison. The results show, depending on the test, a seroprevalence of 4.3% to 7.4%. Seasonal comparison revealed a significant increase of up to 9%. The month with the highest seroprevalence averaged over three years was June with a prevalence of 24.7%. Overall, the findings of this study demonstrate that even the high number of entries does not fully capture the true prevalence of Q fever in cattle herds.