Large ongoing Q fever outbreak in the south of The Netherlands, 2008

Q fever is a worldwide zoonosis caused by the bacterium Coxiella burnetii which is common in a wide range of wild and domestic animals. Cattle and small ruminants, in particular sheep and goats, have been associated with large human outbreaks. Humans become infected primarily by inhaling aerosols that are contaminated by C. burnetii. Most infections remain asymptomatic but in about 40% lead to a febrile disease, pneumonia and/or hepatitis. Chronic infections, mainly endocarditis, are observed in 3 to 5% of cases, with an increased risk for pregnant women and persons with heart valve disorders or impaired immunity. Q fever in pregnancy, whether symptomatic or asymptomatic, may also result in adverse pregnancy outcomes [1]. Q fever in humans is a notifiable disease in The Netherlands. The notification criteria for a confirmed case of acute Q fever are clinical symptoms consistent with Q fever and a positive serology defined by immunofluoresence assay (IFA) test or a C. burnetii complement fixation test [2]. Also clinical patients diagnosed by PCR are considered as confirmed cases. Between 1997 and 2006, Q fever was notified rarely with an average of 11 (range 5-16) cases annually [3]. In 2007, we reported in this journal the first community outbreak of Q fever in the south of The Netherlands [4].