Evaluating the spatial and temporal patterns of the severe fever thrombocytopenia syndrome in Republic of Korea

Abstract

Severe fever with thrombocytopenia syndrome (SFTS) is a new infectious disease with a high mortality rate and increased incidence in Republic of Korea since the first case was reported in 2013. The average mortality rate varies by region and year but remains high in Asia. This study aimed to evaluate the spatial and temporal patterns of SFTS cases reported to the national Disease Control and Prevention Agency (KDCA). We analysed the spatial and temporal distribution of SFTS and observed changes in areas vulnerable to the disease. We analysed data concerning 1086 confirmed SFTS patients from 2013 to 2019 categorized according to the 247 district level administrative units. To better understand the epidemiology of SFTS, we carried out spatiotemporal analyses on a yearly basis and also calculated and mapped spatial clusters of domestic SFTS by global (regional) and local Moran’s indices. To observe the annual changes in SFTS incidence rate, scan statistics for each city and district were calculated. The incidence rate showed significant clustering in specific regions, which reoccurred annually in some regions. In Republic of Korea, SFTS clusters have been expanding into the southern regions, with annual clusters concentrated between May and October. This pattern allows prediction of SFTS occurrences through spatiotemporal analysis, which makes it possible to guide measures of disease prevention.