An infection caused by the bacterium Coxiella burnetii.

Q fever spreads to humans from animals, most often sheep, goats and cattle. Inhaling air polluted by infected animals is the usual cause. Jobs that involve working with animals, such as farming, veterinary medicine and animal research, might increase the risk.

Q fever can cause illness that lasts a short time, known as acute, or a long time, known as chronic. Many people with Q fever have no symptoms. If symptoms occur, they can include high fever, bad headache, cough, nausea and tiredness.

The antibiotic doxycycline treats Q fever. Most people recover completely. Some can develop a more serious or long-term illness.