Serologic Evidence of Human Exposure to Ehrlichiosis Agents in Japan

In retrospective analyses, we report 3 febrile patients in Japan who had seroconversion to antibodies against Ehrlichia chaffeensis antigens detected by using an immunofluorescence and Western blot. Our results provide evidence of autochthonous human ehrlichiosis cases and indicate ehrlichiosis should be considered a potential cause of febrile illness in Japan.