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Clinical manifestations and diagnosis of Q fever

Didier Raoult, MD, PhD
Section Editor
Daniel J Sexton, MD
Deputy Editor
Jennifer Mitty, MD, MPH


Q fever is a zoonotic infection caused by the pathogen Coxiella burnetii, and patients can present with a wide spectrum of clinical manifestations [1]. The designation Q fever (from Query) was made in 1935 following an outbreak of a febrile illness among abattoir (slaughterhouse) workers in Queensland, Australia. The name remains apt, however, since many questions persist about this special organism and unusual disease. Q fever is reportable in the United States and its agent, C. burnetii, is a potential agent of bioterrorism [2].

The clinical manifestations and diagnosis of Q fever will be reviewed here. Topic reviews that discuss the microbiology, epidemiology, treatment, and prevention of Q fever, as well as Q fever endocarditis, are found elsewhere. (See "Microbiology and epidemiology of Q fever" and "Treatment and prevention of Q fever" and "Q fever endocarditis".)


Patients with Q fever present with a wide spectrum of disease manifestations. While for some patients the clinical manifestations of acute or chronic infection are severe [1], the clinical signs and symptoms of Q fever are mild or absent in others [3,4]. As an example, an outbreak of 415 cases of Q fever occurred in Switzerland, and among those infected, 224 (54 percent) were asymptomatic and only 2 percent were hospitalized.

Factors that can affect the clinical presentation include:

Age and gender — Symptomatic infection is more likely to occur in adults compared with children and in men compared with women [5]. In an outbreak in France, surveillance data were obtained to describe variations in the clinical presentation of acute infection according to specific host factors, as well as monitor progression from acute to chronic disease [5]. Serum samples were obtained from over 1000 individuals. Acute Q fever was diagnosed serologically in 101 (9.3 percent). Adult men were most likely to be symptomatic, followed by adult women, and children ≤14 years of age. Pregnant women were the least likely to be symptomatic (ie, 1 of 11 women). Five percent (5/101) patients developed chronic disease, most had no known risk factors (eg, pregnancy, heart disease, immunocompromise).

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Literature review current through: Oct 2017. | This topic last updated: Jun 07, 2016.
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