Seasonal dynamics of tick species as SFTSV vectors in South Korea.

Unlabelled: Ticks pose a significant public health threat due to their ability to transmit various pathogens, including emerging tick-borne diseases. This study conducted a comprehensive surveillance of tick species and their severe fever with thrombocytopenia syndrome virus (SFTSV) infection rates in South Korea throughout the year 2023, from January to December. To ensure accurate and rapid identification of the prevalent tick species in South Korea, we designed PCR primer sets targeting the ITS1 gene, specifically distinguishing from . Among the 10,343 ticks collected from wild animals, constituted the majority, accounting for 65.5% (6,784/10,343 ticks), followed by at 33.8% (3,491/10,343 ticks), and at 0.7% (68/10,343 ticks). These identified ticks were then categorized into 811 pools, with 63 pools testing positive for SFTSV. Remarkably, the prevalence of SFTSV-positive ticks peaked during the summer months, aligning with heightened human outdoor activities and, consequently, an increased risk of human exposure. Conversely, it is noteworthy that exhibited a higher prevalence during the winter season, reaching its peak in January, with an SFTSV minimum infection rate similar to that of . These findings underscore the year-round presence of ticks as potential vectors for SFTSV, extending the temporal window for potential human exposure. Consequently, these results emphasize the necessity for active and continuous field surveillance to comprehensively understand and mitigate the public health risks associated with these tick-borne pathogens.

Importance: To date, the majority of tick surveillance studies have primarily focused on warmer seasons, which are considered optimal periods for ticks to actively seek hosts and transmit pathogens through blood-feeding activities. Consequently, tick species active during winter have often been overlooked, leading to an underestimation of their significance in transmitting severe fever with thrombocytopenia syndrome virus (SFTSV). In this study, we aimed to examine year-round tick prevalence with SFTSV and illuminate the role of the winter-dominant species, a, in South Korea. Through rigorous identification facilitated by a primer set designed specifically for this purpose, we emphasize that , a competent vector species, harbors SFTSV in the winter season, thereby acting as an overwintering reservoir for the virus. This phenomenon may contribute to a higher infection rate among ticks in the following year.