Immunohistochemical detection of Coxiella burnetii in chronic Q fever hepatitis

Abstract

Q fever is a worldwide zoonosis caused by Coxiella burnetii, a strictly intracellular and highly infectious bacterium that lives in the monocyte ⁄macrophage, its host cell. Q fever is characterized by its clinical polymorphism, and develops as acute infections, some of which will evolve to chronic forms [1]. Patients with acute Q fever are more often asymptomatic. The most common syndromes observed in acute Q fever are prolonged fever of unexplained origin, granulomatous hepatitis, and atypical pneumonia. Although infective endocarditis is the main manifestation of chronic Q fever, the other chronic manifestations are vascular infections, chronic infections after pregnancy, and other rare chronic forms such as osteomyelitis, chronic hepatitis, pseudotumour of the lung or infectious arthritis [2]. Liver involvement is common in acute Q fever, and percutaneous liver biopsy can help in the diagnosis. On the other hand, cases of chronic Q fever hepatitis are rarely reported in the literature, and are frequently associated with endocarditis [1–4]. We report in this study the first immunohistochemical detection of C. burnetii in a case of chronic Q fever hepatitis associated with a Q fever endocarditis using a peroxidase-based method and paraffin-embedded tissues.