Why is Coxiella burnetii nearly impossible to eradicate from a farm?

• A. Ubiquitous, persistent in the environment.
• B. Rapidly killed by standard disinfectants.
• C. Only affects dairy cattle.
• D. It is resident in soil but easy to remove.

Answer: (A)

The main idea is that Coxiella burnetii is highly persistent in the environment and widely distributed. It survives outside hosts for long periods because it forms resistant forms that withstand desiccation, heat, and many common disinfectants. It is shed by infected animals in birth products, milk, urine, and feces, often during parturition, and can contaminate barns, dust, and soil. Small amounts of contaminated dust can be inhaled, transmitting infection to people and other animals, and wind can spread contaminated dust between buildings, so exposure can continue even after signs in a herd seem to subside. Many animals may shed intermittently or be asymptomatic carriers, so the source of contamination remains present and difficult to eliminate. Because cleaning and disinfection alone cannot reliably remove all contaminated dust and materials, eradication on a farm is basically unachievable. Control efforts therefore focus on reducing shedding risks (such as managing birth products), vaccination where appropriate, and preventing new introductions of infected animals.