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Coxiella burnetii seropositivity and associated risk factors in sheep, goats, their farm workers and veterinarians in Ontario, Canada

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dc.contributor.advisor Menzies, Paula
dc.contributor.advisor Jones-Bitton, Andria Meadows, Shannon 2014-05-06T19:20:42Z 2014-05-06T19:20:42Z 2014-05 2014-03-13 2014-05-06
dc.description.abstract This thesis was conducted to investigate the seroprevalence and risk factors for Coxiella burnetii exposure in meat and dairy sheep and goats, their farm workers, and small ruminant veterinarians and veterinary students in Ontario. Four cross-sectional studies involving serological testing and questionnaire administration were conducted. Sera from reproductively active ewes and does were tested for C. burnetii specific antibodies using an Enzyme-Linked Immunosorbent Assay (IDEXX); human sera were tested using an Immuno-Fluorescence Assay (Focus Diagnostics). Seropositivity was common among all groups. The individual-level seroprevalence was 14.7% (95% CI=13.3-16.2) in sheep, 32.5% (95%CI=30.6-34.5) in goats, 64.5% (95%CI=57.2-71.4) in farm workers, and 59.4% (95%CI=41.9-75.2) in veterinarians/veterinary students. Overall, 48.6% (95%CI=37.2-60.1) of sheep farms and 63.2% (95%CI=51.9-73.4) of goat farms had at least one seropositive animal, while 76.3% (95%CI=65.8-84.6) of farms that participated in human testing had at least one seropositive farm worker. Mixed logistic multivariable models of individual seropositivity, and controlling for clustering by farm, were constructed for sheep, goats and farm workers. The sheep and goat models highlighted the importance of farm hygiene and biosecurity measures. Female flock size (log10 scale), lambing/kidding in a separate airspace, and failure to disinfect lambing/kidding pens were positively associated with seropositivity in both the sheep and goat models. For goats, male herd size (log10 scale), and kidding outdoors in the absence of swine on farm were negatively associated with seropositivity; the presence of other sheep/goat farms within 5km was positively associated with seropositivity. For sheep, loaning sheep was positively associated with seropositivity. Workers on dairy goat farms had higher odds of seropositivity, compared to working on meat goat or dairy sheep farms. Increasing proportions of seropositive sheep/goats on farm was also positively associated with farm worker seropositivity. Veterinary students had significantly lower odds of seropositivity than practicing veterinarians in univariable exact logistic regression. en_US
dc.description.sponsorship Ontario Ministry of Agriculture, Food and Rural Affairs - University of Guelph Agreement through the Animal Health Strategic Investment fund (AHSI) managed by the Animal Health Laboratory of the University of Guelph; Ontario Ministry of Health and Long-Term Care; National Sciences and Engineering Research Council of Canada; Public Health Ontario; Ontario Sheep Marketing Agency en_US
dc.language.iso en en_US
dc.subject Coxiella burnetii en_US
dc.subject Q fever en_US
dc.subject sheep en_US
dc.subject goats en_US
dc.subject seroprevalence en_US
dc.subject risk factors en_US
dc.title Coxiella burnetii seropositivity and associated risk factors in sheep, goats, their farm workers and veterinarians in Ontario, Canada en_US
dc.type Thesis en_US Population Medicine en_US Doctor of Philosophy en_US Department of Population Medicine en_US
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