Studies on Tsutsugamushi and Tsutsugamushi-disease of Hachijo Island

Abstract

The author made three years' studies on trombiculid mites and Tsutsugamushi disease of Hachijo Island, about 350km south of Tokyo. A total of 10 species of the mites were recovered from this island, and their seasonal and areal distributions were investigated. Two species were found to be epidemiologically important. Trombicula scutellaris which appears in winter and probably transmits Shichito-type Tsutsugamushi disease prevalent in this area, and Trombicula wichmanni which appears in summer and causes severe itches. Tsutsugamushi disease in this island was also investigated from clinical as well as from epidemiological points of view. This was characterised with its appearance in the winter season and with the extremely low mortality, differing from that in the classical endemic foci of northwest Honshu.