Q fever and prevention

Coxiella burnetii is an intracellular, Gram-negative bacterium and the etiological agent of Q fever, a worldwide zoonotic disease with a considerable economic impact in the livestock industry. Domesticated ruminants like cattle, sheep, and goats are the main reservoirs of Q fever in men. Humans usually acquire the disease by inhaling contaminated aerosol produced by infected livestock. Acute infection is typically asymptomatic or manifests as a febrile flu-like illness or pneumonia. In 1-5% of primary infections, chronic Q fever may develop, which can be life-threatening and often presents as endocarditis. Q fever outbreaks usually occur from occupational exposure involving shepherds, veterinarians, animal handlers, abattoir or dairy workers, and laboratory personnel working with C. burnetii. Thus, prevention and control efforts should be primarily directed toward these groups and the surrounding environment. The most effective way of prophylaxis is vaccination. Although clinical data are lacking, vaccination should also be considered for persons who are at higher risk for development of chronic Q fever, including those with cardiac valve defects, vascular aneurysms, and immunocompromised patients. Therefore, development of an effective and harmless vaccine is a subject of constant interest of researchers for decades. This review summarizes the progress toward Q fever vaccine development.