Serologic evidence of acute murine typhus infection in a patient with culture-negative endocarditis

A patient with culture-negative infective endocarditis is presented in whom detailed serological studies were indicative of acute infection with murine typhus. The patient had aortic and mitral regurgitation with congestive heart failure and typical peripheral manifestations of subacute endocarditis, but no documented fever. Aortic and mitral valve replacement surgery and a 6-week course of doxycycline therapy produced a clinical cure in this patient, as well as a diagnostic fall in markedly elevated preoperative typhus indirect fluorescent antibody (IFA) and complement fixation (CF) titers. Serological studies were consistently negative for Q fever.