Severe fever with thrombocytopenia syndrome (SFTS) is an infection due to a virus of the Phlebovirus genus and Bunyaviridae family. This infection was first identified in farmers in China. The viral vector is thought to be the Haemaphysalis longicornis tick. Person-to-person transmission of SFTS virus has occurred in China, South Korea, and Japan.

Patients present with fever and multiorgan dysfunction. Laboratory studies reveal thrombocytopenia and leukopenia. The clinical manifestations are similar to infection with the Heartland virus, which can be seen in the United States. The diagnosis is clinical. Some specialized research laboratories may be able to isolate viral ribonucleic acid using the polymerase chain reaction on blood samples.