Q fever

Definition:

An infectious disease which causes pneumonia, acquired from animals. The initial form occurs as Q fever (early); a chronic or relapsing form also exists, called Q fever (late).

Causes, incidence, and risk factors:

Q fever is caused by the organism Coxiella burnetii. This organism primarily lives in domestic animals (cattle, sheep, and goats), cats, wild animals, and ticks.

Humans contract the disease after having contact with contaminated materials (materials that have been contaminated with the animal's feces, blood, placenta, etc.), after inhaling contaminated dust or droplets, or after ingestion of contaminated food or raw (unpateurized) milk.

Hepatitis or pneumonia may develop in early disease. Late Q fever involves relapse or persistence of the initial infection; although rare, it can cause severe complications including of the aortic heart valve (and subsequent endocarditis).