Human ehrlichioses: Diagnostic challenges and therapeutic recommendations

The clinical spectrum of human ehrlichioses ranges from mild febrile illnesses to fatal infections. Laboratory diagnosis of these diseases is based on immunofluorescent assays (IFAs) and therefore requires a convalescent serum sample to demonstrate seroconversion or rising antibody titers. More sophisticated techniques, such as Western immunoblotting using recombinant proteins, show great promise. Diagnosis during the acute phase, in which IFA is usually nondiagnostic, is based on polymerase chain reaction assays. Cultivation of the organisms is difficult and impractical. The treatment of choice is a tetracycline; within this group, doxycycline is the preferred drug because of its better tolerance and lower incidence of side effects.