[Epidemiological characteristics of severe fever with thtrombocytopenia syndrome in China, 2011-2021].

Objective: To analyze the epidemiological characteristics of severe fever with thrombocytopenia syndrome (SFTS) in China from 2011 to 2021, and provide evidence for the prevention and control of SFTS. Methods: The incidence data of SFTS were collected from the National Disease Reporting Information System of Chinese Center for Disease Control and Prevention for a descriptive epidemiological analysis and Cochran-Armitage trend test was used to evaluate the association between age and the morbidity rate and case fatality rate (CFR) of SFTS. Results: From 2011 to 2021, a total of 18 902 laboratory confirmed cases of SFTS, including 966 deaths, were reported in 533 counties (districts) of 154 prefecture-level cities in 27 provinces. The annual average morbidity rate was 0.125/100 000, and the annual average CFR was 5.11%. From 2011 to 2021 the overall morbidity rate of SFTS was in increase with an average annual percentage change (AAPC) of 14.80% (P=0.001). Most cases (99.23%) occurred in 7 provinces, including Shandong, Henan, Anhui, Hubei, Liaoning, Zhejiang and Jiangsu, with 70.28% of the cases in 11 prefecture-level cities. The average annual CFRs in the 7 provinces varied greatly from 1.30% to 11.27%. In 2011, SFTS cases were reported in 108 counties (districts) of 51 prefecture-level cities in 13 provinces, but SFTS cases were reported in 277 counties (districts) of 88 prefecture-level cities in 19 provinces in 2021, the disease spread from central area to the northeast and from the west and the south. SFTS mainly occurred in summer and autumn in both southern and northern China, and 96.63% of the cases were reported from April to October, and the incidence peak was during May-June. The cases mainly occurred in age group 50-74 years (69.46%), and the deaths mainly occurred in age group ≥60 years (79.71%). Both the morbidity rate and the CFR increased with age. The morbidity rate increased from 0.040/100 000 in age group 0-4 years to 4.480/100 000 in age group ≥80 years in males (χ²=13 185.21, P<0.001) and from 0.038/100 000 in age group 0-4 years to 3.318/100 000 in age group ≥80 years in females (χ²=12 939.83, P<0.001); the CFR increased from 0.70% in age group 30-34 years to 11.58% in age group ≥80 years in males (χ²=115.70, P<0.001) and from 1.56% in age group 35-39 years to 8.98% in age group ≥80 years in females (χ²=103.42, P<0.001). Conclusion: From 2011 to 2021, the incidence of SFTS increased in China, and the spread and obvious spatiotemporal distribution of SFTS were observed. The reported CFR varied greatly with area, and both the morbidity and mortality risk were high in the elderly.目的： 了解2011-2021年我国发热伴血小板减少综合征（SFTS）的流行特征，为修订防控策略提供依据。 方法： 从中国疾病预防控制信息系统传染病报告信息管理系统获取SFTS数据，采用描述性流行病学方法，用Cochran-Armitage趋势检验验证发病率、病死率随年龄变化趋势。 结果： 2011-2021年全国27个省154个地级市533个县（区）共报告SFTS确诊病例18 902例，死亡966例，年均发病率为0.125/10万，年均病死率为5.11%。此11年间全国SFTS发病率整体呈上升趋势，平均年度变化百分比为14.80%（P=0.001）。全国99.23%的病例集中于河南、山东、湖北、安徽、江苏、浙江和辽宁7个省，70.28%的病例集中于11个地级市。上述7个省年均病死率差别较大（1.30%~11.27%）。报告地区由2011年13个省51个地级市108县（区），上升到2021年的19个省88个地级市277县（区），从中部向东北、西部和南方扩散。南、北方发病均集中在夏、秋季，4-10月发病数占全年的96.63%，5-6月达高峰。发病年龄集中在50~74岁年龄组（69.46%），死亡病例集中在≥60岁年龄组（79.71%）。发病率和病死率均随年龄增加：发病率男性由0~4岁年龄组的0.040/10万增加到≥80岁的4.480/10万（χ²=13 185.21，P<0.001），女性由0~4岁年龄组的0.038/10万增加到≥80岁的3.318/10万（χ²=12 939.83，P<0.001）；病死率男性由30~34岁年龄组的0.70%增加到≥80岁的11.58%（χ²=115.70，P<0.001），女性由35~39岁年龄组的1.56%增加到≥80岁的8.98%（χ²=103.42，P<0.001）。 结论： 2011- 2021年我国SFTS发病呈上升、扩散趋势，具有明显时空聚集性；不同地区报告病死率差别较大，中老年人群发病及病死风险高。.