Q fever epidemic among employees in a factory in the suburb of Zadar, Croatia.

AIM To examine the role of wind in the spread of Q fever (Coxiella burnetii) from the source of infection (sheep on the pastures) to the factory where there was an outbreak of Q fever among the employees. METHODS We performed clinical (fever, coughing, myalgias, arthralgias), laboratory (complete blood test, aminotransferases, antibodies to Coxiella burnetii), radiographic (chest X-ray), and epidemiological (questionnaire) analysis on 47 of 110 employees of the plant in a suburb of Zadar. Sera of 182 sheep were tested for antibody to C. burnetii by complement fixation reaction. RESULTS During the first half of March 2004, 14 of 110 employees of a factory in a suburb of Zadar were diagnosed with Q fever on the basis of clinical and laboratory findings. In three sections of the plant, directly exposed to the north wind, a diagnosis of Q fever was confirmed in 14 of 110 employees by clinical, laboratory, and X-ray analysis, whereas there were no sick employees in the other four sections. North of the plant there were pastures where many flocks of sheep grazed. Antibodies to C. burnetii were found in 20 out of 182 sheep sera. Employees who were exposed to the north wind, had a significantly higher possibility of acquiring Q fever than did those working in sections protected from the wind. CONCLUSION North wind (bura) containing the aerosolized C. burnetii likely influenced the Q fever outbreak in persons far from the source of the infection.