Investigating coxiella burnetii at the livestock - wildlife interface

Abstract

The intent of this project was to better understand the role of wildlife in the epidemiology of the zoonotic bacterium, Coxiella burnetii, at the livestock-wildlife interface. In Chapter 1, I compared the prevalence of C. burnetii DNA in dairy goats, other domestic animals, and wildlife on goat farms and adjacent natural areas. In Chapter 2, I compared the prevalence of C. burnetii DNA in different sample types from goats and wildlife, and assessed the level of agreement among the different samples. From April to August 2014, genital, fecal and milk samples were collected from goats on 16 Ontario dairy goat farms. Fecal and genital samples were also collected from other resident animals (cats, chickens, cows, dogs, horses, pigs), and from wildlife (deer mice, house mice, opossums, raccoons, red-backed voles, red squirrels and skunks) live-trapped on farms and from 14 adjacent natural areas. Coxiella burnetii was detected by PCR in samples from 89.2% (404/453) of goats, 68.8% (33/48) of other farm animals, 64.7% (44/68) of wild animals sampled on farms, and 58.1% (165/284) of wild animals sampled in natural areas. Coxiella burnetii was detected at all study sites and the prevalence in wildlife was similar on farms and adjacent natural areas, independent of site distances. These findings provide evidence to support the hypothesis that wildlife are able to maintain C. burnetii independent of livestock and may act as possible maintenance or reservoir hosts of C. burnetii at the livestock-wildlife interface. I determined that genital and fecal swab samples, which yielded the highest proportion positives, were optimal sample types to use for the detection of C. burnetii DNA in deer mice, eastern chipmunks, and raccoons. Genital swab, fecal swab and fecal material sample types were all suitable for detecting C. burnetii DNA in house mice and red squirrels. On the other hand, genital swab samples were optimal for detecting C. burnetii DNA in dairy goats and were significantly more likely to be positive for C. burnetii DNA than the other sample types. Additional studies need to be conducted to further elucidate the epidemiology of C. burnetii at the livestock-wildlife interface in southern Ontario and to confirm the optimal sample types to use for C. burnetii detection in wildlife and dairy goats.