Abstract / Summary
Abstract Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne viral disease with high case-fatality rates in East Asia. While hard ticks are recognized as the primary vectors of SFTS virus (SFTSV), the detection of SFTSV RNA in chigger mites suggests their involvement in viral maintenance in natural conditions. In this study, wild rodents were captured at 17 sites across the Republic of Korea in 2019, and spleen tissues and mites were collected and tested for SFTSV RNA using RT-PCR. To evaluate transovarial transmission, Leptotrombidium sp. collected from an endemic area were reared under laboratory conditions. Among 56 rodents and 3,402 mites, SFTSV RNA was detected in 3.6% of rodents and 2.3% of mite pools (minimum infection rate of 0.09%). Phylogenetic analysis revealed that all viral sequences clustered within genotype B. SFTSV RNA was detected in both parental mites and their F1 larvae, providing molecular evidence suggestive of transovarial transmission. This study provides the first molecular evidence suggestive of transovarial transmission of SFTSV in chigger mites under laboratory conditions and indicates that chigger mites may contribute to the natural maintenance of the virus. Further animal model-based studies are needed to clarify their vector competence.