Circulation of Severe Fever with Thrombocytopenia Syndrome Virus (SFTSV) in Nature: Transmission of SFTSV Between Mammals and Ticks

Abstract

Severe fever with thrombocytopenia syndrome (SFTS) caused by SFTS virus (SFTSV), a novel phlebovirus, was reported to be endemic to central and northeastern China, South Korea, and Japan. SFTS is a tick-borne viral infection with high morbidity and mortality. SFTSV is circulating in nature in the SFTS-endemic areas. SFTSV is maintained in nature between animals and some species of ticks. Humans are usually infected with SFTSV by virus-positive ticks, especially Haemaphysalis longicornis and Amblyomma testudinarium. The mechanism of SFTSV maintenance in nature is crucial to control SFTSV infections in humans. Antibody positive rates to SFTSV in some species of animals such as goats, deer, old aged bovine, and wild boar were reported to be relatively high. Virus genomes were detected in some species of ticks such as H. longicornis, H. flava, H. concinna, A. testudinarium, and Ixodes nipponensis. Animal species, which were studied for SFTSV antibody and SFTSV genome prevalence, are still limited. Based on the data reported so far suggest that SFTSV is maintained in nature through intensive transmission between animals such as goats, deer, and wild boars and Haemaphysalis, Ambryomma, and Ixodes ticks. Further studies are needed to clarify the SFTSV maintenance mechanism in nature in detail.