Reactivation of Q fever following cardiac surgery.

To determine whether reactivation of Q fever occurs following cardiac surgery 43 patients who had antibodies to Coxiella burnetii were identified pre-operatively. Serum samples were collected 1, 4 to 6, and 24 weeks post-operatively. One patient had active Q fever endocarditis. Seven of the remaining 42 (17%) had a > or = fourfold rise in titres for antibodies to Coxiella burnetii post-operatively. Only two of these seven had an increase in antibody titres for other agents suggesting that the fourfold titre rise for Coxiella burnetii was not part of a polyclonal response. It is concluded that self-limited reactivation of infection may occur among Coxiella burnetii seropositive patients undergoing open heart surgery.