Q fever is a common zoonosis (infection that could transmit from animals to humans), caused by Coxiella burnetii. Natural reservoirs include several domestic and wild animals, most of which show no signs of disease (although infection can cause abortions). Due to the high resilience in the environment of Coxiella, humans are most often infected by inhalation of aerosols produced in contaminated locations, but other modes of infection have been documented (including food-borne).
After an incubation period of, usually, 2–3 weeks, disease symptoms may appear but more frequently they do not. A serious clinical picture can suddenly emerge characterised by high fever, eye infection, respiratory tract infection, and severe headache. Occasionally, the infection takes a chronic course, leading to infection of the heart valves, hepatitis and other organ involvement. Acute cases respond to appropriate antibiotic treatment but infected heart valves may require surgery.
The mainstays of prevention aim at avoiding the production and inhalation of contaminated dust and the consumption of potentially contaminated food (e.g. unpasteurised milk).