Contributions of different host species to the natural transmission of severe fever with thrombocytopenia syndrome virus in China

Severe fever with thrombocytopenia syndrome (SFTS) is a tick-borne emerging infectious disease with a reported mortality rate of up to 30% in hospitalized patients. The causative agent, SFTS virus (SFTSV) is maintained in nature through a transmission cycle involving animal hosts and ticks. Therefore, effective control of SFTS in nature environments necessitates a comprehensive understanding of the tick-host circulation patterns that sustain viral persistence. We developed and calibrated mathematical models using seroprevalence survey data collected across China to assess the relative contributions of diverse domestic and wildlife host species to transmission, their determinants, and the effectiveness of various interventions. Our analysis identified poultry, previously unrecognized, as the most important species across the majority of survey sites, followed by goat/sheep, cattle, and rodents. These rankings remained robust even when parameter values were perturbed or certain host species were omitted from the survey. Across all sites, increasing tick mortality rate μT and reducing transovarial transmission efficiency ϕ consistently ranked among the top five interventions that led to the most significant reduction in the overall R0. Understanding the relative host contributions is crucial for developing interventions. Our simulation results indicated that halving the contact rate of the most important species with ticks could yield a 25-fold greater reduction in transmission intensity compared to halving that of the second most important species.Author summary: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne disease characterized by rapid spread, a broad host range among vertebrates, high case fatality rate in humans, and potential for global dissemination due to the wide distribution of its main vector Haemaphysalis longicornis. Despite being identified nearly two decades ago, the specific contributions of different host species to its natural persistence remain poorly understood. In this study, we compiled published seroprevalence data across various host species from mulitple locations in China and calibrated mathematical models for each location. Our analyses identified poultry, previously unrecognized, as the most important species at the majority of locations, followed by goat/sheep, cattle, and rodents. Through simulations, we found that increasing tick mortality, reducing transovarial transmission efficiency, and lowering the contact rate between ticks and the most important host species are the most effective interventions for reducing local transmission intensity. Notably, halving the contact rate of the most important species with ticks could yield a 25-fold greater reduction in transmission intensity compared to halving that of the second most important species.