Severe fever with thrombocytopaenia syndrome (SFTS)

Severe fever with thrombocytopaenia syndrome (SFTS)

Severe fever with thrombocytopaenia syndrome (SFTS) is caused by the SFTS virus (SFTSV), also known as Huaiyangshan banyangvirus, in the order Bunyavirales (bunyavirus), genus phlebovirus.

First isolated from human blood in 2009:

• is a Chinese lineage of SFTSV containing 6 sub-lineages, and a Japanese lineage containing 4 sub-lineages

SFTS is a tick-borne zoonosis, but human-to-human can also occur. Most infections occur in rural areas in at-risk countries, where there is an increased presence of ticks.

Human cases were first identified in Central and Eastern China and further cases have been identified in Western Japan, South Korea and Taiwan

• SFTSV has 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

From 2010 to 2019, a total of 13,824 SFTS cases (8,899 lab-confirmed and 4,925 probable cases) were reported in mainland China, including 713 deaths (average annual fatality rate of 5.2% nationally).

• estimated that 4.7% of populations in endemic areas of China have antibodies against SFTSV . Lower numbers of cases have been reported by Japan and South Korea
• cases tend to peak between May and July in China, May and October in South Korea, and April and August in Japan. Case fatality rates have varied between reporting countries from 5.2% in China to 32.6% in the South Korea

Any suspected cases in England should be discussed with local infection specialists and with the Imported Fever Service (IFS) (24 hour telephone service: 0844 778 8990).

Laboratory Diagnosis:

• reverse transcription polymerase chain reaction (RT-PCR). Serology for SFTSV antibodies is not available

Treatment:

• is no proven, specific treatment for SFTS, and there is no preventative vaccine. Treatment is predominantly supportive, including use of blood products to manage haemorrhagic complications
• ribavirin has been administered to patients with SFTS, but there is no conclusive evidence of therapeutic effect. Experimental treatments have been proposed, including favipiravir therapy

Reference:

• Public Health England (April 2021). Severe fever with thrombocytopaenia syndrome (SFTS): epidemiology, outbreaks and guidance