Risks factors and prevention of Q fever endocarditis

Coxiella burnetii causes acute and chronic Q fever. To evaluate the risk fa ctors of development of chronic endocarditis following Q fever and to asses s the best preventive therapy, a retrospective study of patients diagnosed as having Q fever during 1985-2000 was conducted. Twelve patients with acut e Q fever who developed endocarditis and 102 patients with Q fever endocard itis were included in the study. When compared to 200 control patients with acute Q fever, preexisting valvular disease (P<10(-7)), especially a prost hetic valve (P=.01), were encountered more often among patients with endoca rditis. Among patients with valvular defects, we estimate the risk of devel oping endocarditis to be 39%. A combination of doxycycline plus hydroxychlo roquine was better at preventing the development of endocarditis than doxyc ycline alone (P = .009). Our results should encourage physicians to detect valvular lesions in patients with acute Q fever and to search for acute Q f ever in patients with a valvulopathy and unexplained fever. A proper treatm ent for such patients and a scheduled follow-up should reduce the risk of d eveloping endocarditis.