SFTSV Prevalence in Ticks and Livestock in an SFTSV-Endemic Area in Central China

Severe fever with thrombocytopenia syndrome virus (SFTSV) is an emerging tick-borne bunyavirus that causes a severe viral hemorrhagic fever (SFTS), with a very high case mortality rate, expanding epidemic areas, and increasing incidence. Due to the lack of an effective drug or vaccine for SFTS, reducing the incidence and mortality of SFTS primarily relies on decreasing the density of ticks and the number of their host animals. However, which tick species and vertebrate animal serve as the major reservoir and animal host of SFTSV are not clearly understood. In May of 2023 and June of 2024, we collected 2437 ticks from domesticated animals and grassland in Suizhou City, a prefecture of Hubei Province in central China. A total of 195 domesticated animal blood samples were collected, including 152 goats, 26 cattle, and 17 dogs. Ticks were grouped for RNA extraction according to their life stages and feeding status. RNA from each animal's blood and each group of ticks was extracted with an RNA extraction kit and tested for SFTSV with RT-PCR. Ticks were classified according to morphology, and representative ticks of each stage were confirmed with PCR amplification and DNA sequencing of the mitochondrial 16S RNA gene. Among the collected ticks, the majority were from goats (72.7%, 1772/2437), and Haemaphysalis longicornis was predominant, accounting for 99.47% (2425/2437), and other tick species were very rare, with 0.45% (11/2437) Rhipicephalus microplus, and 0.04% (1/2437) H. flava and Ixodes sinensis, respectively. We found SFTSV RNA in H. longicornis ticks with a minimum infection rate of 0.17% (4/2424) and in one goat (0.66%,1/152). In summary, we demonstrated that the H. longicornis tick is positive for SFTSV and that the goat is the major host of Haemaphysalis longicornis in Suizhou, central China. Our study suggests that controlling ticks on goats may play an important role in preventing SFTSV infection in China.