Q Fever Endocarditis in a Saudi Child: A Case Report and Literature Review

Q fever is a zoonotic disease that is caused by Coxiella burnetii, a gram-negative coccobacillary bacterium. Human infection primarily occurs following the inhalation of aerosols containing C. burnetii. The infection can either present in an acute or chronic form. The three main presentations are flu-like syndrome, atypical pneumonia, and hepatitis. Chronic Q fever mainly affects the heart where the disease manifests as endocarditis. In this case report, the patient was born at term with congenital heart defects, namely double outlet right ventricle (DORV), ventricular septal defects (VSD), and coarctation of the aorta. He underwent coarctation repair and pulmonary artery binding. At the age of three years, he presented with palpitation, sudden high-grade fever, myalgia, and dyspnea. Endocarditis was suspected due to a history of a surgical repair of congenital heart defects. Blood cultures were negative, however, a diagnosis of Q fever endocarditis was confirmed based on serologic titers. Q fever endocarditis is a challenging diagnosis since the echocardiography findings are often nonspecific. Moreover, Q fever can present as negative-culture endocarditis with low sensitivity of blood and tissue polymerase chain reaction (PCR) for C. burnetii. Hence, the modified Duke criteria has considered phase 1 immunoglobulin G (IgG) titers of 1:800 or more as diagnostic for infective endocarditis. Although uncommon, physicians should maintain a high index of suspicion for Q fever endocarditis, especially among patients with pre-existing structural heart disease and associated symptoms and risk factors such as animal exposure.