Epidemiological characteristics of severe fever with thrombocytopenia syndrome in China, 2010−2021

Objective To analyze the epidemiological characteristics of severe fever with thrombocytopenia syndrome (SFTS) in China, especially in areas with high incidences, during 2010−2021.

Methods Descriptive epidemiological indicators, such as concentration ratio, circular distribution, spatial distribution map, were used to analyze the temporal, spatial, and demographic characteristics of the SFTS cases. The differences in cases’ demographic characteristics in areas with high incidences were analyzed with χ² test.

Results From 2010 to 2021, a total of 18 968 cases of SFTS were reported in 27 provinces, with an average annual incidence rate of 0.11/100 000, and a total of 973 SFTS deaths were reported in 11 provinces, with a case fatality rate of 5.13%. The annual incidence of SFTS showed seasonality with only one peak from May to August. The annual incidence rate increased, slightly decreased and then increased again during 2010−2021, and annual case fatality rate decreased from 2010 to 2021. The cases and deaths of SFTS in areas with high incidences, such as Shandong, Henan, Anhui, Hubei and Liaoning provinces, accounted for 92.97% and 89.21%, respectively, and the disease also expanded to southwestern, northeastern, eastern and western China. The male to female ratio of the cases was 0.89∶1. The annual incidence rate in people over 50 years old was higher, and the cases in farmers accounted for 86.02%. The male to female ratio of the SFTS deaths was 1.12∶1. The reported SFTS cases in Henan reached its peak in 2015 and then declined significantly. Since 2018, the reported cases in Shandong and Anhui have ranked the top two in China. The male to female ratio of the cases in Liaoning was 1.15∶1, while there were less cases being reported in men in other four provinces.

Conclusion From 2010 to 2021, the incidence rate of SFTS in China showed an upward trend and the case fatality rate showed a downward trend. The disease expanded from the areas with high incidences to southwestern, northeastern, eastern, and western China. It is suggested to strengthen the health education about SFTS prevention and control and conduct early case detection and treatment to prevent the further spread of the disease.