Q fever (Coxiella burnetii)
Short orientation
Q fever is a highly infectious zoonosis caused by the obligate intracellular bacterium Coxiella burnetii. Human infection most commonly follows inhalation of contaminated aerosols from infected ruminants (sheep, goats, cattle), particularly birth products, bedding and dust.
Contaminated hides, wool or (less commonly) unpasteurised milk may also be sources. Clinical presentations range from asymptomatic infection to an acute febrile illness with atypical pneumonia or hepatitis.
Chronic disease - most importantly endocarditis - occurs in a minority, typically in patients with pre‑existing valvular disease or vascular prostheses.
Early recognition, focused investigations, liaison with microbiology/infectious diseases (ID) and public‑health teams, and appropriate empirical therapy where indicated are priorities in the emergency department.
Epidemiology and transmission
- Reservoirs: primarily sheep, goats and cattle; other mammals, birds and arthropods can carry the organism.
- Main route of transmission: inhalation of contaminated aerosols (birth products, placental tissue, bedding, soil, dust).
- Other routes: contact with contaminated hides or wool; ingestion of unpasteurised milk (less common).
- Infectious dose: very small; C. burnetii is environmentally resilient and can persist in dust.
- Incubation period: typically about 2-3 weeks (commonly 1-4 weeks).
- Risk groups: farmers, abattoir and veterinary workers, livestock transporters, laboratory staff, visitors to farms or agricultural fairs.