Genotype analysis of severe fever with thrombocytopenia syndrome viruses in Gyeonggi Province of South Korea from 2017 to 2022

Severe fever with thrombocytopenia syndrome (SFTS) is a tick-borne infectious disease that was first identified in South Korea in 2013. To investigate the SFTS virus (SFTSV) genotypes in Gyeonggi Province, SFTSV detected in 126 patient serum samples collected between 2017 and 2022 was subjected to genetic analysis. Among SFTSV genotypes A to F, SFTSV genotype B was the most common, found in a total of 101 cases (80.2%). Within genotype B, there were 85 cases of subgenotype B-1 (67.5%) and 16 cases of subgenotype B-2 (12.7%), but no cases of subgenotype B-3. Five cases of genotype F (3.9%), one of genotype C (0.8%), and one of genotype D (0.8%) were identified. No genotype A or E strains were found. Of the 108 patients for whom epidemiological information was available, 16 (14.8%) died, 75 (68.5%) recovered, and the outcome was unknown for 18 (16.7%) patients. Although the number of samples tested was not large enough to allow a concrete conclusion, subgenotype B-1 showed the highest fatality rate (16.5%). The high prevalence and lethality of SFTSV subgenotype B-1 in a local region of South Korea showed that continuous monitoring of SFTSV genotypes is necessary.