Although C. burnetii is an obligate intracellular pathogen, the organism is persistent in the environment and resistant to heat and antiseptics. C. burnetii is highly infectious and is efficiently transmitted to humans through aerosols. The organism can easily be isolated from animals in natural settings, and could potentially be used as an agent for bioterrorism. The incidence of naturally occurring Q fever in the United States is unknown, and the geographic distribution of this disease remains undefined due to a lack of available data. National surveillance for Q fever should be implemented in order to better evaluate current epidemiologic patterns of infection, and to distinguish naturally occurring outbreaks from intentional release of the agent.
Severe disease can include acute hepatitis, pneumonia, and meningoencephalitis.
Clinical laboratory findings may include elevated liver enzyme levels and abnormal chest film findings. Asymptomatic infections may also occur. A chronic fatigue-like syndrome has been reported in some Q fever patients. I antigen in paired serum specimens ideally taken 3-6 weeks apart, or, Isolation of C. burnetii from a clinical specimen by culture, or Demonstration of C. burnetti in a clinical specimen by detection of antigen or nucleic acid. Cutoff titers are determined by individual laboratories.