Seroprevalence and risk factors of antibodies against Coxiella burnetii among dog owners in southwestern Quebec, Canada

Coxiella burnetii is a zoonotic agent responsible for human Q fever, a potentially severe disease that can lead to persistent infection. This cross-sectional study aimed to estimate the seroprevalence to C. burnetii antibodies and its association with potential risk factors in the human population of five regions of Quebec, Canada. A serum bank comprising sera from 474 dog owners was screened by an enzyme-linked immunosorbent assay followed by confirmation of positive or equivocal sera by an indirect immunofluorescence assay. Observed seroprevalences of 1.2% (95% confidence interval (CI): 0.0-6.6), 2.6% (95% CI: 0.5-7.4) and 5.9% (95% CI: 3.4-9.6) were estimated in the regions of Montreal, Lanaudiere and Monteregie, respectively, which all included at least 83 samples. Having lived or worked on a small ruminant farm (prevalence odds ratio (POR) = 5.4; 95% CI: 1.6-17.7) and being a veterinarian or veterinary student (POR = 6.1; 95% CI: 1.6-24.0) were significantly associated with C. burnetii seropositivity. Antibodies against C. burnetii were detected in the human population of Quebec. Although seropositivity to this agent was associated with occupational contact with domestic animals, antibodies were also detected in people with no reported professional exposure. No associations with ruminant farm proximity were identified.