Detection, Isolation and Characterization of an Agent from Febrile Patients in Malaysia Serologically Reactive with Rickettsia sennetsu

摘要

The possible role of Rickettsia sennetsu or R. sennetsu-like agents in the etiology of fever of unknown origin (FUO) among military and civilian populations in Southeast Asia has been examined. Seroepidemiologic studies on 1,208 serum samples obtained from patients with FUO residing in Malaysia and the Philippines revealed the presence of anti-R. sennetsu antibodies in 30% of the samples examined. Isolation studies using whole blood collected from some of the above seropositive patients were performed in an attempt to isolate the etiologic agent. A rickettsia-like agent (temporarily designated no. 11908) was successfully isolated from the blood of one of the above patients from Malaysia. Preliminary cross-serologic studies revealed the agent to be closely related, but not identical, to R. sennetsu. Biochemical and immunochemical characterization of purified R. sennetsu membrane proteins revealed the presence of two major and four minor proteins. Future studies are aimed towards the identification of the antigenic relationship between the Ehrlichia-sennetsu group agents.