Clinical, virological, and pathological findings in a fatal case of Q fever endocarditis.

A case resembling subacute bacterial endocarditis in which blood cultures were repeatedly negative is described. The patient had had an influenza-like illness nine months before admission to hospital followed by intervening vague illness and loss of weight. Serological tests revealed a high titre of complement-fixing antibodies to phase 1 and phase 2 antigens of Rickettsia burneti. After death R. burneti was isolated from the diseased aortic valve, liver, and kidneys. Bodies morphologically resembling rickettsiae were seen in the aortic valve and in a very few renal tubule cells. No specific pathological lesions were found but there was a widespread stimulation of reticulo-endothelial cells particularly in the aortic valve cusps, spleen, lymph nodes, and renal glomeruli. It is suggested that tests for Q fever should be carried out in suspected cases of subacute bacterial endocarditis when blood culture is negative.