Severe fever with thrombocytopaenia syndrome (SFTS): epidemiology, outbreaks and guidance

This content was originally produced by Public Health England (PHE). This content is now owned and managed by the UK Health Security Agency (UKHSA).

Severe fever with thrombocytopaenia syndrome (SFTS), caused by SFTS virus (SFTSV), was first isolated from human blood  in 2009 in China.

SFTS is a tick-borne zoonosis, but rare cases of human-to-human transmission have been clearly documented. Most human infections occur in individuals exposed to ticks in rural mountainous areas of Central and Eastern China.  Cases have also been identified in Japan, South Korea, Taiwan and Thailand.  SFTSV has additionally been detected retrospectively in stored blood samples from patients with thrombocytopaenia in Vietnam, and there are reports of serological evidence of SFTS infection in Pakistan.

See the HCID: country specific risk webpage for further information.

Seroprevalence studies have estimated that 4.7% of populations in endemic areas of China have antibodies against SFTSV.

SFTS is a seasonal disease with cases seen predominantly between May and July in China, May and October in South Korea, and April and August in Japan. Reported case fatality rates have varied between countries from 5.2% in China to 32.6% in South Korea.

The primary vector is the Asian long-horned tick, Haemaphysalis longicornis, which has demonstrated north and westward expansion in China, and into new regions in South Korea and Japan. Although it can be found in Australia, New Zealand, islands in the Western Pacific region and in the USA, there are no reports of SFTSV having been detected in ticks in these countries. Several other types of tick can be infected with SFTSV in endemic countries, though their role in transmission to humans is less clear.