RESUMEN
To estimate the prevalence of spotted fever (SF) and murine typhus (MT) rickettsioses in Southeast Asia, we performed serosurvey by immunoperoxidase test on local residents in Taiwan and Thailand, comparing them with those of Japan. In Japan, the prevalence of antibodies (1:80 as cut-off level) to some SF/MT antigens was noticeable in Japanese SF-endemic areas or a high-risk groups. In Tainan, Taiwan, SF antibodies were not so prevalent (3.5 to 4.4%), but MT antibodies were more prevalent (23.9%). In Chiang Rai in northern Thailand SF antibodies were markedly prevalent (9.0 to 21.3%); the reactivity with Thai tick 118 strain alone was 8.2%, but MT was less (2.5%). These results suggest that these rickettsioses may be latently distributed in various parts of Asia.