Epidemiological Characteristics of Severe Fever with Thrombocytopenia Syndrome from 2010 to 2019 in Mainland China

< 0.05. A total of 13,824 SFTS cases involving 8899 lab-confirmed cases and 4925 probable cases were reported and included in the epidemiological analysis. Our study found that the number of SFTS cases showed an increasing trend with a small decrease in the past three years. The laboratory-confirmed rate was about 64.4%, which varied between different years and areas. Although most cases (99.3%) were distributed in 7 provinces (Henan, Shandong, Anhui, Hubei, Liaoning, Zhejiang, and Jiangsu), the regional distribution of SFTS gradually expanded from 5 provinces in 2010 to 25 provinces by 2019, especially at the town level. The SFTS cases were mainly sporadic. A total of 96.5% occurred from April to October, and 93.3% of cases were concentrated in middle-aged and elderly people (40-84 years old). Farmers were the main high-risk population. Female cases were slightly more than male cases; however, there were differences between different provinces. The mortality rate showed an increasing trend with age. Overall, the SFTS cases were mainly middle-aged and elderly farmers that sporadically distributed throughout seven provinces with a spatially expanding trend. The laboratory-confirmed rate varied in different years and provinces, which implied that the diagnosis and report criteria for SFTS should be further updated and unified in order to get a better understanding of its epidemiological characteristics and provide scientific data for SFTS control.