An unexpected Q fever endocarditis. Report of a case.

A man with blood culture negative endocarditis since 1983 received in October 1984 a mitral valve bioprosthesis. Reintervention in April 1985 was performed because of a paravalvular leak. In September 1985, mitral insufficiency reappeared and high-titer phase II Q fever antibody was detected, which has since then persisted with concomitant high-titers of phase I antibody. In serum from 1983, phase II antibody was detected on reexamination in September 1985. For unexplained reasons this antibody had not been detected in 1983. The patient has since September 1985 been successfully treated with doxycycline. The current literature is reviewed. Q fever endocarditis should be considered also in Belgium in culture negative endocarditis even in persons with no previous history of valvular disease and no known exposure to animals or unpasteurized dairy products. Quality of viral reagents and diagnosis present sometimes a challenge.