Spotted fever group rickettsiosis on Awaji Island, Japan

Three cases of spotted fever group rickettsiosis occurring on Awaji Island, Hyogo Prefecture, the first reported in the Kinki District, are described. The illness appeared from August to September in 1988. High-grade fever and papular erythema were observed in all cases. Eschar, lymphadenopathy and hepatomegaly were observed in two-thirds of the cases, respectively. The antibody titers for Proteus OX-2 by the Weil-Felix reaction were elevated, and immunofluorescence test with R. rickettsii of the spotted fever group demonstrated a significant rise in specific antibody titer. Tetracycline was effective in all cases. Every patient was thought to have been infected with rickettsiae in the Yuzuruha mountain range in the southern part of Awaji Island. On the other hand, tsutsugamushi disease occurs in autumn and winter in the northern part of Awaji Island. It would be of considerable interest from an epidemiological viewpoint to study the vector of these spotted fever group rickettsiae.