[Surveillance for sever fever with thrombocytopenia syndrome in Henan province, 2017-2020].

Objective: To analyze the epidemiological and etiological characteristics of sever fever with thrombocytopenia syndrome (SFTS) cases in Henan province during 2017-2020. Methods: Descriptive epidemiology method was used to analyze the characteristics of SFTS cases in Henan during 2017-2020. Patients' sera in acute phase were collected and tested using real-time fluorescence RT-PCR. The S segment complete sequences of the isolated sever fever with thrombocytopenia syndrome virus (SFTSV) strains were amplified and homology analysis was performed to construct the phylogenetic tree. Results: A total of 1 767 SFTS cases, including 1 000 suspected cases and 767 confirmed cases, were reported in Henan during this period, and 11 cases, including 3 suspected cases and 8 confirmed cases died, the case fatality rate was 0.62% (11/1 767). The incidence decreased year by year. The cases were distributed in 28 counties of 6 cities, and 1 681 cases were reported in Xinyang, accounting for 95.13% (1 681/1 767) of the total. The cases mainly occurred from April to October, accounting for 96.10% (1 698/1 767) of the total. The incidence in males (0.38/100 000) was significantly lower than that in females (0.54/100 000) (χ2=54.855, P<0.001). Up to 93.44% (1 651/1 767) of the cases were aged between 40 and 84 years. Farmers accounted for 96.10% (1 698/1 767) of the total cases. One family cluster outbreak occurred in 4 years. A total of 1 110 samples were detected by Henan CDC, in which 435 were SFTS virus positive with an average positive rate of 39.19% (435/1 110). The differences in positive rates of SFTS virus among different years were significant (χ2=25.405, P<0.001). The sequence homology of complete S segment of the 39 SFTS virus strains ranged from 94.76% to 99.82%. The genetic evolution analysis on the complete S segment of the 39 SFTS virus strains showed that 34 strains belonged to genotype A, 2 strains belonged to genotype B, and 3 strains belonged to genotype D. Conclusions: The incidence of SFTS in Henan was sporadic, and decreased year by year. SFTS had obvious regional and seasonal characteristics, and the area affected by SFTS expanded. The incidence of SFTS was high in elderly female farmers, and the positive rate of SFTS virus varied greatly in different years. The main type of SFTS virus in Henan was genotype A, but the etiological surveillance is still needed.目的： 了解河南省2017-2020年发热伴血小板减少综合征（SFTS）监测病例的流行病学和病原学特征。 方法： 利用描述流行病学方法对河南省2017-2020年SFTS病例特征进行分析。采集急性期病例血标本，应用实时荧光RT-PCR法检测新布尼亚病毒核酸。对部分分离到的病毒株扩增S片段基因，进行同源性分析，构建系统进化树。 结果： 2017-2020年河南省共报告SFTS 1 767例（疑似病例1 000例、确诊病例767例），累计死亡11例（疑似病例3例、确诊病例8例），平均病死率为0.62%（11/1 767）；发病呈逐年下降趋势（趋势χ2=12.018，P=0.001）。病例分布在6个城市28个县（区），信阳市报告1 681例，占病例总数的95.13%（1 681/1 767）。病例主要发生在4-10月，占病例总数的96.10%（1 698/1 767）。男性发病率（0.38/10万）低于女性（0.54/10万）（χ2=54.855，P<0.001）；40~84岁占病例总数的93.44%（1 651/1 767）；农民占病例总数的96.10%（1 698/1 767）。发生家庭聚集性疫情1起。共检测标本1 110份，新布尼亚病毒的平均阳性率为39.19%（435/1 110），不同年份的差异有统计学意义（χ2=25.405，P<0.001）。分离到39株新布尼亚病毒中，S片段核苷酸同源性为94.76%~99.82%。39株病毒株完整S片段遗传进化分析结果显示，34株为A基因型、2株为B基因型，3株为D基因型。 结论： 2017-2020年河南省SFTS以散发为主，发病呈逐年下降趋势，发病具有明显的地域性和季节性，发病范围不断扩大，女性、≥40岁和农民多发，不同年份新布尼亚病毒阳性率差异较大，新布尼亚病毒主要流行型别为A基因型，但仍需持续开展病原学监测。.