Epidemiological characteristics and spatial aggregation of severe fever with thrombocytopenia syndrome (SFTS) in Dalian city from 2011 to 2023

Objective To analyze the epidemiological characteristics and spatial clustering of severe fever with thrombocytopenia syndrome (SFTS) in Dalian from 2011 to 2023, and provide evidence for the prevention and control of SFTS. Method The incidence data of SFTS wer obtained from the National Disease Reporting Information System of Chinese Center for Disease Control and Prevention and referral tracking of all SFTS confirmed cases by CDC in all districts, cities and counties under the jurisdiction of Dalian Municipality. The epidemiological charac-teristics and spatial aggregation of SFTS were analyzed by descriptive analysis, Joinpoint regression analysis, and spatial autocorrelation analysis. Result From 2011 to 2023, a total of 701 laboratory confirmed cases of SFTS, including 166 deaths. The annual average morbidity rate was 0.77/100 000 (0.15/100 000 – 1.93/100 000), and the CFR was 23.68%. The overall morbidity rate of SFTS in Dalian had an increasing trend from 2011 to 2023 was in increase with an average annual percentage change (AAPC) of 24.00% (P < 0.05). And the mortality rate had a increasing trend from 2011 to 2023 with an average annual percentage change (AAPC) of 20.95% (P < 0.05). The cases mainly occurred from Apirl to October and the incidence peak was in summer. The middle-aged and elderly farmers were the main SFTS population.The top three areas of incidence number were 228 cases of Zhuanghe city, 194 cases of Pulandian city, 156 cases of Wafangdian city. Global spatial autocorrelation analysis showed that the spatial aggeration occurred in the incidence of SFTS from 2017 to 2023 (P < 0.05). Local spatial autocorrelation analysis showed that "High-high clustering" areas were mainly concentrated in the mountainous areas of northern Dalian such as Zhuanghe, Pulandian and Wafangdian. Conclution From 2011 – 2023, the incidence of SFTS increased in Dalian, and the spread and obvious spatially cluesterd were observed. The morbidity and mortality risk were high in the elderly. The incidence of SFTS was seasonal.