Definition of Q fever - early:

Q fever is an infectious disease caused by the bacteria Coxiella burnetii.

Causes, incidence, and risk factors:

Q fever is caused by Coxiella burnetii, an organism that lives in domestic animals such as cattle, sheep, goats, and cats. Some wild animals and ticks also carry the bacteria.

People get Q fever after exposure to contaminated food or raw (unpasteurized) milk, or after inhaling dust or droplets in the air which are contaminated with animal feces, blood, or birth products.

Symptoms usually develop 2 to 3 weeks after you come in contact with the bacteria. This is called the incubation period. Some people may have no symptoms; others may have moderately severe symptoms similar to the flu. If symptoms occur, they may last for several weeks.

People at risk for infection include slaughterhouse workers, veterinarians, researchers, food processors, and sheep and cattle workers. Men are more commonly infected than women, and most patients are between 30 and 70 years old.

This disorder is occasionally seen in children, especially those who live on a farm. In infected children younger than 3 years old, Q fever is usually discovered during a search for the cause of pneumonia.