S evere fever with thrombocytopenia syndrome (SFTS) is an emerging tickborne infectious disease, identified in 2009 in the rural areas of Hubei and Henan provinces in China (1,2); a total of 7,419 cases were reported from 23 provinces during 2010-2016 (3). SFTS is endemic not only to China but also to South Korea and Japan (4,5). Huaiyangshan banyangvirus (formerly SFTS virus [SFTSV]), the causative agent of SFTS, belongs to the genus Banyangvirus in the family Phenuiviridae. Although the name of the virus has recently been changed from SFTSV to Huaiyangshan banyangvirus by the International Committee on Taxonomy of Viruses (6), the term SFTSV is still used. SFTSV is found in tick species such as Haemaphysalis longicornis, Amblyomma testudinarium, and Ixodes nipponesis in China, South Korea, and Japan (7-9). Antibodies to SFTSV were detected in wild and domestic animals, such as goats, deer, cattle, dogs, and cats, in SFTS-endemic areas of these 3 countries (10-15). SFTSV is thought to circulate in an