The First Identification and Retrospective Study of Severe Fever With Thrombocytopenia Syndrome in Japan

Takahashi, Toru; Maeda, Ken; Suzuki, Tadaki; Ishido, Aki; Shigeoka, Toru; Tominaga, Takayuki; Kamei, Toshiaki; Honda, Masahiro; Ninomiya, Daisuke; Sakai, Takenori; Senba, Takanori; Kaneyuki, Shozo; Sakaguchi, Shota; Satoh, Akira; Hosokawa, Takanori; Kawabe, Yojiro; Kurihara, Shintaro; Izumikawa, Koichi; Kohno, Shigeru; Azuma, Taichi; Suemori, Koichiro; Yasukawa, Masaki; Mizutani, Tetsuya; Omatsu, Tsutomu; Katayama, Yukie; Miyahara, Masaharu; Ijuin, Masahito; Doi, Kazuko; Okuda, Masaru; Umeki, Kazunori; Saito, Tomoya; Fukushima, Kazuko; Nakajima, Kensuke; Yoshikawa, Tomoki; Tani, Hideki; Fukushi, Shuetsu; Fukuma, Aiko; Ogata, Momoko; Shimojima, Masayuki; Nakajima, Noriko; Nagata, Noriyo; Katano, Harutaka; Fukumoto, Hitomi; Sato, Yuko; Hasegawa, Hideki; Yamagishi, Takuya; Oishi, Kazunori; Kurane, Ichiro; Morikawa, Shigeru; Saijo, Masayuki

Background. Severe fever with thrombocytopenia syndrome (SFTS) is caused by SFTS virus (SFTSV), a novel bunyavirus reported to be endemic in central and northeastern China. This article describes the first identified patient with SFTS and a retrospective study on SFTS in Japan. Methods. Virologic and pathologic examinations were performed on the patient's samples. Laboratory diagnosis of SFTS was made by isolation/genome amplification and/or the detection of anti-SFTSV immunoglobulin G antibody in sera. Physicians were alerted to the initial diagnosis and asked whether they had previously treated patients with symptoms similar to those of SFTS. Results. A female patient who died in 2012 received a diagnosis of SFTS. Ten additional patients with SFTS were then retrospectively identified. All patients were aged ≥50 years and lived in western Japan. Six cases were fatal. The ratio of males to females was 8:3. SFTSV was isolated from 8 patients. Phylogenetic analyses indicated that all of the Japanese SFTSV isolates formed a genotype independent to those from China. Most patients showed symptoms due to hemorrhage, possibly because of disseminated intravascular coagulation and/or hemophagocytosis. Conclusions. SFTS has been endemic to Japan, and SFTSV has been circulating naturally within the country.