2020 年 37 巻 4 号 p. 648-652
Severe fever with thrombocytopenia syndrome (SFTS) was first discovered as an emerging virus infection caused by a novel bunyavirus, which is classified to the Banyangvirus Genus in the Phenuiviridae Family (Huaiyangshan banyangvirus, former SFTS virus, SFTSV) in 2011. SFTS was also reported to be endemic not only to China, but also to Japan, South Korea, Vietnam, and Taiwan. The major symptoms of SFTS are gastrointestinal symptoms such as fever, general fatigue, nausea, vomiting, and diarrhea. Total blood cell counts revealed thrombocytopenia and leukopenia in patients with SFTS. Approximately seven years have passed since the discovery of SFTS patient in Japan. Forty to 100 patients with SFTS have been reported annually to the National Institute of Infectious Diseases from western part of Japan. Case fatality rate of SFTS is approximately 27–31%. The reasons behind the high case fatality rate might be that multiorgan failure, coagulopathy, and hemophagochtosis are induced in most SFTS patients. It was reported that an antiviral drug, favipiravir, was effective in the treatment of SFTSV infection in an animal infection model. SFTSV is circulating between wild animals and several species of ticks in nature, indicating that we cannot escape the risk of being infected with SFTSV and that SFTS will continue to occur in the endemic areas. Furthermore, it has been revealed that humans can also be infected with SFTSV through close contact with sick animals such as cats and dogs, both of which were also infected with SFTSV. Development of specific treatment and preventive measures with SFTS vaccines is necessary.
