This document reviews the military relevance and characteristics of Q fever.
Q fever is a zoonotic disease caused by Coxiella burnetii, a rickettsia-like organism of low virulence but remarkable infectivity. A single organism may initiate infection. The C burnetii can persist in the environment for long periods (weeks or months) under harsh conditions. This persistence along with a primary mode of transmission by inhalation of infected aerosols allows for the development of acute infection following only indirect exposure to an infected source. The acute clinical disease associated with Q fever infection is usually a benign, although a temporarily incapacitating, illness in humans. Even without treatment, the vast majority of patients recover. Chronic disease as a result of Q fever is rare, although it is frequently fatal. Humans who work in animal husbandry, especially those who assist during calving or lambing are at risk for acquiring Q fever. However, a definite risk also exists for persons who live in close proximity to, or who pass through, an area where animal birthing is occurring, even if this occurred months previously. Thousands of cases involving military personnel have been reported since 1937, and infection should be considered a possibility whenever troops are present in an area with infected animals. When symptomatic, the onset of Q fever may be abrupt or insidious, with fever, chills, and headache being the most common signs or symptoms. Chronic infection is usually manifested by infective endocarditis, which is also the most severe complication of Q fever. Diagnosis is usually accomplished by serologic testing because culture of C burnetii is potentially hazardous to laboratory personnel and requires animal inoculation or cell culture. Treatment with tetracyclines is effective. Prevention is possible with a formalin-killed, whole-cell vaccine, but prior skin testing to exclude immune individuals is necessary to avoid severe local reactions to the vaccine. A Q fever vaccine is licensed in Australia, but not in the United States, where all Q fever vaccines are investigational. 97 references