Abstract
From January 1984 to March 1996,1,060 small wild mammals were captured in 80 selected survey sites in Kyoto Prefecture. A total of 115,092 trombiculid mites which belonged to 7 genera and 21 species were recovered from these mammals. By analyzing the results of isolation of Orientia tsutsugamushi and the distribution pattern of trombiculids, we concluded that Leptotrombidium pallidum was the only vector mite of Tsutsugamushi disease endemic in the Nodagawa River basin of Kyoto Prefecture. Mammals captured from several sites in the Nodagawa River basin were more heavily infested with L. pallidum larvae than those at other sites in Kyoto Prefecture. Seasonal emergence pattern of L. pallidum on small mammals in the Nodagawa River basin showed two peaks, one in late autumn and the other in spring, but its activity was not the same on different species of the host rodents. Nevertheless, as activities of vector mites on hosts are more evident in late autumn than in spring, the seasonal incidence of Tsutsugamushi disease in Kyoto Prefecture is most likely from late spring to early summer. It is considered that the preferance of vector mites for hosts influenced the number of cases or seasonal incidence of Tsutsugamushi disease.
