Felis ISSN 2398-2950

Q fever

Synonym(s): Coxiella burnetii infection

Contributor(s): Gad Baneth, Leah Cohn


  • Q fever is the name applied to infection caused by the Gram negative obligate intracellular organism, Coxiella burnetii. Primarily important as a cause of abortion in ruminant livestock and as a zoonotic pathogen, Q fever is rarely symptomatic in cats and even more rarely symptomatic in dogs.
  • Coxiella burnetii Coxiella burnettii is resistant to disinfection, remains infectious at low doses, and can be easily spread by aerosolization. These factors make it a potential agent of bioterrorism.



  • Coxiella burnetii is a Gram negative obligate intracellular pathogen historically considered aRickettsia.

Predisposing factors


  • Infection in pet dogs and cats may be caused by inhalation of contaminated dusts, ingestion of contaminated materials including birth products from infected ruminants, or via infected arthropods including ticks. Although ticks can be infected with C. burnetii, the role ticks play in transmission of infection to pets is unknown.
  • Because the predominant sign of infection in companion animals is abortion/stillbirth, only sexually intact, pregnant females may demonstrate illness related to infection.


  • Reservoir hosts include multiple domestic and wild animal species, birds, and arthropods. Biting ectoparastitic arthropods such as ticks likely play a role in spread of the infection, especially in the sylvan setting.
  • The bacterium has two distinct life stages. Although it is an obligate intracellular organism inside the host, an endospore form (which is resistant to harsh environmental conditions) exists in the environment.
  • The large-cell form is the metabolically active intracellular state associated with acute infection.
  • The small-cell form is the metabolically inactive stage. This stage may be found in tissues of chronically infected animals during latent infection, and it is this stage which persists in the environment.
  • Acute infection may be cleared without clinical consequences.
  • Pathophysiology of infection in pet animals is not well documented. Chronic infection can result after the organism disseminates to multiple organs haematogenously. The bacterium survives inside cell phagosomes.
  • In subclinically infected animals, the organism appears to remain latent until pregnancy and parturition.


  • After experimental infection, fever, lethargy, anorexia, and splenomegaly may occur. These signs are self-limiting, with most animals returning to good health.
  • During pregnancy, the latent infection may become reactivated. New infection or reactivation of latent infection may result in abortion, stillbirths, or birth of weakened neonates. Occasionally, normal pregnancy and healthy offspring result from infected animals.


  • The large majority of infected cats and dogs remain healthy.
  • Seroepidemiologic studies suggest that up to 45% of cats may have exposure to C. burnetii
  • In at least one study, stray cats were more likely to be seropositive than pet cats.
  • Cats may be a major reservoir for human infection in urban settings.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Egberink H, Addie D, Belák S et al (2013) Coxiellosis/Q Fever in Cats: ABCD guidelines on prevention and management. J Feline Med Surg 15 (7), 573-575 PubMed.
  • Arricau-Bouvery N & Rodolakis A (2005) Is Q fever an emerging or re-emerging zoonosis? Vet Res 36 (3), 327-349 PubMed.
  • Komiya T, Sadamasu K, Toriniwa H et al (2003) Epidemiological survey on the route of Coxiella burnetii infection in an animal hospital. J Infect Chemother (2), 151-155 PubMed.
  • Komiya T, Sadamasu K, Kang M I et al (2003) Seroprevalence of Coxiella burnetii infections among cats in different living environments. J Vet Med Sci 65 (9), 1047-1048 PubMed.
  • Raoult D, Tissot-Dupont H, Foucault C et al (2000) Q fever 1985- 1998: clinical and epidemiologic features of 1, 383 infections. Medicine (Baltimore) 79 (2), 109-123 PubMed.
  • Buhariwalla F, Cann B, Marrie T J (1996) A dog-related outbreak of Q fever. Clin Infect Dis 23 (4), 753-755 PubMed.
  • Pinsky R L, Fishbein D B, Greene C R et al (1991) An outbreak of cat-associated Q fever in the United States. J Infect Dis 164 (1), 202-204 PubMed.
  • Marrie T J, Langille D, Papukna V et al (1989) Truckin' pneumoniaan outbreak of Q fever in a truck repair plant probably due to aerosols from clothing contaminated by contact with newborn kittens. Epidemiol Infect 102 (1), 119-127 PubMed.
  • Marrie T J, Durant H, Williams J C et al (1988) Exposure to parturient cats: a risk factor for acquisition of Q fever in Maritime Canada. J Infect Dis 158 (1), 101-108 PubMed.

Other sources of information