Definition of Q fever - early:

Q fever is an infectious disease that is spread by domestic and wild animals and ticks.

Causes, incidence, and risk factors:

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

People get Q fever after exposure to 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 coming 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 infected more often than women, and most people who get Q fever are between 30 and 70 years old.

This disease 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.