Since 1993, no cases infected with high pathogenic Kato type of Orientia tsutsugamushi (O.tsutsugamushi) had occurred. However, in August, 2008, we found a patient with tsutsugamushi disease (scrub typhus) who had the antibody against Kato serotype antigen the titer of which was raised at the level of the convalescent phase. The patient resided along Omono river, Daisen city, Akita Prefecture, Japan. We surveyed the vector mites and the field mice as hosts around the endemic locality, from spring to autumn, 2009. We found out Leptotronbidium akamushi (L. akamushi) and succeeded to isolate the Kato type of O. tsutsugamushi from the field mice at the endemic locality. L. akamushi were also found at the famous place for national fireworks in Daisen city, not so distant from the endemic locality. In order to avoid additional latent infections among the local residents or tourists, it is necessary to enlighten that there is risk of infection with this disease along Omono river in summer.
