Risk factors of Coxiella burnetii (Q fever) seropositivity in veterinary medicine students.

ABSTRACT

BACKGROUND: Q fever is an occupational risk for veterinarians, however little is known about the risk for veterinary medicine students. This study aimed to assess the seroprevalence of Coxiella burnetii among veterinary medicine students and to identify associated risk factors. METHODS: A cross-sectional study with questionnaire and blood sample collection was performed among all veterinary medicine students studying in The Netherlands in 2006. Serum samples (n = 674), representative of all study years and study directions, were analyzed for C. burnetii IgG and IgM phase I and II antibodies with an immunofluorescence assay (IFA). Seropositivity was defined as IgG phase I and/or II titer of 132 and above. RESULTS: Of the veterinary medicine students 126 (18.7%) had IgG antibodies against C. burnetii. Seropositivity associated risk factors identified were the study direction 'farm animals' (Odds Ratio (OR) 3.27 [95% CI 2.14-5.02]), advanced year of study (OR year 6 2.31 [1.22-4.39] OR year 3-5 1.83 [1.07-3.10]) having had a zoonosis during the study (OR 1.74 [1.07-2.82]) and ever lived on a ruminant farm (OR 2.73 [1.59-4.67]). Stratified analysis revealed study direction 'farm animals' to be a study-related risk factor apart from ever living on a farm. In addition we identified a clear dose-response relation for the number of years lived on a farm with C. burnetii seropositivity. CONCLUSIONS: C. burnetii seroprevalence is considerable among veterinary medicine students and study related risk factors were identified. This indicates Q fever as an occupational risk for veterinary medicine students.