Contribution of rickettsioses in Sri Lankan patients with fever who responded to empirical doxycycline treatment.

Twenty-eight febrile Sri Lankan patients with undiagnosed fever for 7 days after hospital admission, who responded to empirical treatment with doxycycline, were retrospectively investigated using microimmunofluorescence assay to verify whether they had rickettsial infection. Eleven (39%) patients were confirmed as having spotted fever group rickettsioses and 10 (36%) as having Orientia tsutsugamushi. Seven were negative for all tests. This suggests that greater use of doxycycline appears justified for patients with undiagnosed fever in settings where rickettsial diseases are endemic or re-emerging with inadequate diagnostic facilities.