Coxiella burnetii is the causative agent of zoonotic query fever (Q fever) and is distributed worldwide. The pathogen is an obligate intracellular bacterium of which there are two antigenic forms: phases 1 and 2. It forms spore-like particles that enable the organism to survive extracellularly for years, even under unfavourable environmental conditions. Infections with C. burnetii occur in many wild as well as domesticated animals. Numerous tick species are reservoirs for the pathogen. Coxiellosis is usually asymptomatic but chornic in ruminants such as cattle, sheep and goats. Premature births, abortions, reduced reproductive rate and infertility may occur. Infected animals excrete the pathogen in the chronic phase with their faces and urine as well as in their milk. Particularly high concentrations can be detected in amniotic fluid and afterbirths.
Professional groups such as farmes, veterinarians, shepherds or slaughterhouse staff, as well as laboratory workers, are at extremely high risk of infection. Transmission generally occurs through inhalation of infectious aerosols or dusts. The chronic course with pneumonia, endocarditis, hepatitis and neurological symptoms is feared.