秋田県におけるShimokoshi型つつが虫病の遡及的疫学調査

抄録

We confirmed 15 cases of Shimokoshi-type tsutsugamushi disease from 1992 to 2008 in Akita prefecture, Japan. Clinical findings of these cases showed diversity, including mild to severe cases. These cases were widely distributed through Akita prefecture, and the seasonal occurrence was mainly in spring (from April to June) and also in autumn (from October to November).
DNA of the Shimokoshi-type Orientia tsutsugamushi could be detected in three samples using Shimokoshi-type specific PCR including novel primer designed in this study. Additionally, we isolated a strain from one sample by cell culture system, as the second strain of Shimokoshi-type in Japan. It was showed that 10 of 15 patients could not determine of serotype or not diagnosed as tsutsugamushi disease by serological test without Shimokoshi-type antigen at the past time, because of low cross-reactivity between Shimokoshi-type and other antigens (Gilliam, Karp, and Kato). Most of laboratories have not ever used Shimokoshi-type antigen in serological diagnostic test, under the recognition as rare infection with this type.
Hence, it is necessary to improve the diagnosis system for detection of Shimokoshi-type, in addition to investigate about human pathogenicity and vector for Shimokoshi-type.