Abstract
In the spring and autumn of 2007 and 2008, wild rodents were captured in five regions of Yamagata Prefecture where cases of tsutsugamushi disease have been reported. Attached trombiculid larvae were collected from the captured rodents. In the spring, 7,695 trombiculid larvae were collected from 65 wild rodents and classified into 9 species in 3 genera. Numerous cases of tsutsugamushi disease have been reported in areas where Leptotrombidium pallidum is the major species among collected larvae, so this high incidence is likely attributable to a substantial distribution of L. pallidum. In autumn, 8,498 trombiculid larvae were collected from 112 wild rodents and classified into 11 species in 3 genera. Leptotrombidium scutellare not observed in these areas since the 1980's, was collected from Sakegawa-Village and Tozawa-Village. Moreover, the Orientia tsutsugamushi gene of the Kawasaki type was detected by nested PCR from the spleen of two wild rodents captured in the autumn from Sakegawa-Village. Kawasaki type-tsutsugamushi disease, recognized as rare in the Tohoku-district, may be endemic to some parts of Yamagata Prefecture.
