Detection of Coxiella burnetii DNA in animal and environmental matrices on non-dairy sheep farms

During the spring and summer of 2007, 2008 and 2009, large Q fever outbreaks occurred in the Netherlands affecting a rural area in the southeast of the country. Prior to and during these outbreaks Q fever related abortion waves were reported on several dairy goat farms in the same region. As a result, primarily commercial dairy goat farms were implicated as potential sources for the emerging human Q fever cases in the Netherlands. However, in 2008 and 2009 a number of (non-dairy) sheep farms were identified where C. burnetii DNA was detected in both animal (vaginal swabs) and environmental (surface area swabs) matrices. In addition, in two epidemiological studies non-dairy sheep farms were implicated as the primary source for an emerging cluster of human Q fever cases in their near vicinity. Therefore, although less important in the recent epidemic, non-dairy sheep farms cannot be ruled out as potential source for human Q fever. <br>In the current study, we describe the presence of C. burnetii DNA in animal and environmental matrices obtained from two non-dairy sheep farms. We show that C. burnetii DNA content in surface area swabs from fences and drinking buckets and udder swabs from animals was consistently higher on farm B in comparison to farm A. This may be explained by the geographical locations of the farms, since farm B is located in a highly Q fever affected area (Noord-Brabant), while farm A is located in an area not affected by Q fever (Noord-Holland). How these results are related to shedding of C. burnetii by the non-dairy sheep on these farms is not clear. No positive relationship was found between C. burnetii content in vaginal swabs and udder swabs. Coxiella burnetii contamination of sheep udders may be a result from excrements from the same animal, direct contact with other animals (or other contaminated surfaces), or a combination of these.