Isolation of Orientia tsutsugamushi from patients in Shikoku and finding of a strain which grows preferentially at low temperatures

Three strains of Oriemtia tsutsugamushi were isolated from patients in Anan City, Tokushima Prefecture, The strains were identified as Karp type by an alyses of reactivities with type-specific monoclonal antibodies. One strain , Okazaki, was isolated in L cells cultivated at 31 C, but not in cells at 36 C or in mice. This strain showed better growth at 31 C than 36 C. This i s the first report of an O, tsutsugamushi strain which grows preferentially at low temperatures.