Management of a <i>Coxiella</i> <i>burnetii</i>-infected sheep flock after an outbreak of Q fever in humans

Abstract

Following an outbreak of Q fever in a group of students who contracted the infection during a training course on a sheep farm, a detailed investigation of the sheep flock involved was conducted. Of 478 flock animals, 60 Coxiella burnetii ELISA-positive and 60 ELISA-negative ewes were selected for the trial and divided into four groups. A month after the initial ELISA screening, all ewes in the flock (except the control group) were vaccinated. Sequentially collected blood samples were tested with ELISA and PCR; feces, milk, manure, bedding, and soil were tested with PCR. The immune response to the vaccination was 92.7%, while the overall C. burnetii seroprevalence in the flock after the human outbreak was 64.9%. PCR was positive for 0.2% of milk samples and 34.4% of fecal samples of animals from all four trial groups. C. burnetii DNA was not detected in any of the blood samples. Manure was PCR-positive for about 35 months; bedding from the stable was also positive while samples of pasture soil were negative. It appears that extensive cleaning and disinfection combined with vaccination could be regarded as an appropriate approach to control/prevent Q fever in farm settings even in the short term.