Which bacterium causes Q fever, a zoonotic disease often linked to infected livestock?

Coxiella burnetii causes Q fever, a zoonotic disease often linked to infected livestock.

The bacterium is associated especially with cattle, goats, and sheep. Humans can become infected mainly by inhaling contaminated dust or aerosols from birth products, feces, urine, milk, or other materials from infected animals. Q fever often causes a nonspecific febrile illness, so its diagnosis may require targeted serological or molecular testing.

C. burnetii is unusually resistant in the environment and has a very low infectious dose. It is an obligate intracellular bacterium, meaning it normally multiplies inside host cells. Although many infections resolve, chronic disease can develop, including endocarditis in people with particular underlying heart-valve conditions.

The name “Q fever” comes from “query fever,” reflecting the unexplained fevers seen in early investigations. It is different from brucellosis, another livestock-associated infection, and from tularemia, which is caused by Francisella tularensis.