Cow fever – High seroprevalence of Coxiella burnetii antibodies in veterinarians associated with obstetric activity on cattle, Germany, 2009

Background: Q fever is a zoonosis caused by Coxiella burnetii (COX). The clinical picture ranges from asymptomatic infection to severe chronic disease. Little is known about the risk of COX infection in populations with frequent animal exposure. We investigated risk factors (RF) for COX seropositivity in veterinarians to improve recommendations for early diagnosis and prevention of chronic COX infections in veterinarians. Methods: Attendants of the 2009 Bavarian Veterinarians Conference were invited to complete an exposure questionnaire and provide serum. Sera were tested for COX phase II IgG (ELISA) and, if positive, phase II IgM (ELISA), phase I and II IgG antibodies (IFT). We assessed associations between exposures and seropositivity using Chi-square test or Fisher's exact test, where appropriate, and multivariable logistic regression. Results: The 424 participants' median age was 40 (18–74) years, 276 (65%) were female. Sera of 162 (38%) were positive for phase II IgG antibodies. Of these, 13 (8%) reported a history of Q fever. In 17 (4%), chronic Q fever could not be excluded (phase I and II IgG IFT ≥1:512). RF for seropositivity identified in the multivariable analysis were cattle obstetrics (adjusted odds ratio 3.5; 95% confidence interval 1.7–7.1), working with COX infected animals (3.8; 1.1–13.3), and increasing age (1.04; 1.01–1.07/year); dogs/cats obstetrics were protective (0.4; 0.1–0.97). Unexplained joint pain (prevalence ratio 1.4; 1.1–1.8), pneumonia (1.7; 1.2–2.4), and hepatitis (2.2; 1.5–3.2) were bivariably associated with seropositivity. Discussion: The high COX antibody prevalence in veterinarians implies a high lifetime risk of Q fever for this occupational group. Especially veterinarians frequently performing cattle obstetrics should be counselled on the clinical picture of Q fever and on specific risks at an early point in their career. We recommend an assessment of risks, costs and benefits of a screening programme in this occupational setting.