四川省2004-2018年钩端螺旋体病流行特征分析

Epidemiological characteristics of leptospirosis in Sichuan province,2004-2018

目的了解2004-2018年四川省钩端螺旋体病(钩体病)流行病学特征,为防控策略提供依据。方法钩体病数据来源于全国法定传染病疫情监测网络直报系统和11个监测点数据,采用描述性流行病学方法分析,采用ArcGIS 10.2软件进行地图绘制,采用SaTScan 9.1.1软件进行时空扫描分析,描述钩体病时空聚集性特征。结果2004-2018年四川省报告钩体病发病2834例,死亡41例,发病率0.23/10万,死亡率0.003/10万,发病趋势波动向下。发病有明显季节性,主要集中在8月下旬至9月底,较水稻收割时间晚1~2周。男性为主,男女性别比为2.05:1;发病率较高的为50~65岁组。职业以农民为主,占82.75%(2345/2834);其次为学生,占12.74%(361/2834),但2011年后学生病例报告极少。高发地区在南部长江流域沿岸马边彝族自治县(马边县)、沐川县等和东部嘉陵江流域仪陇县之间不断交替。时空扫描聚集性分析发现2个高发聚集区域(P<0.001)。11个监测点2004-2018年平均鼠密度为5.44%(14351/263767);主要野外鼠种有四川短尾鼩(占69.07%)、黑线姬鼠(占12.73%)等;其中黑线姬鼠密度介于4.60%~0.19%之间,呈持续下降趋势,2018年达最低水平。鼠肾标本培养钩体阳性率的各年度间也呈下降态势。2007-2018年健康人群血清钩体抗体阳性率平均为24.52%(3271/13339),主要流行菌群为黄疸出血群,近年未出现菌群的更替。结论2004-2018年四川省钩体病发病水平极低,季节特征符合稻田型流行特征,人群以老年农民为主;高发地区在长江和嘉陵江流域周边互相交替。黑线姬鼠密度和带菌率均较低;主要流行菌群持续以黄疸出血群为主,健康人群钩体抗体阳性率处于较低水平。

Objective To explore the epidemiological characteristics of leptospirosis in Sichuan province from 2004 to 2018,and provide evidence for the prevention and control of leptospirosis.Methods The descriptive epidemiology analysis was conducted based on the epidemic data of leptospirosis collected from the national notifiable infectious disease reporting information system(NNIDRIS)and sentinel surveillance system in 11 areas in Sichuan from 2004 to 2018.The ArcGIS 10.2 software was used for mapping.The SaTScan 9.1.1 software was used to analyze spatio-temporal scanning and characteristics of temporal-spatial clusters of leptospirosis.Results A total of 2834 cases of leptospirosis,including 41 deaths,were reported in Sichuan from 2004 to 2018,and the reported morbidity rate was 0.23/100000 and the mortality rate was 0.003/100000.It revealed that leptospirosis had an overall downward fluctuated trend.The incidence of leptospirosis had obvious seasonality,mainly from the last ten-day of August to the end of September,1-2 weeks later after rice harvesting time.The reported cases were mainly males,the male to female ratio of the cases was 2.05:1.The incidence was higher in age group 50-65 years.The majority of reported cases were farmers,accounting for 82.75%(2345/2834),followed by students,accounting for 12.74%(361/2834).However,rare cases in students had been reported since 2011.In recent years,the high-incidence areas were alternating between Mabian,Muchuan counties along the Yangtze River and Yilong county located in the Jialing River basin.According to the spatial-temporal descriptive analyses by SaTScan,there were two clustering areas in the province where most cases occurred(P<0.001).The average density of field rats in 11 sentinel surveillance areas was 5.44%(14351/263767),and the predominant field rats included Anourosorexsquamipes(69.07%),Apodemusagrarius(12.73%).Whatmore,the density of the Apodemusagrarius ranged from 4.60%to 0.19%,showing downward trend with the lowest level in 2018.The annual culture rate of Leptospira from rat kidney samples declined.During 2007-2018,the average positive rate of Leptospira antibodies in healthy people was 24.52%(3271/13339),and the predominant serogroup was Icterohaemorrhagiae.There was no replacement of Leptospira serogroup in recent years.Conclusions The incidence of leptospirosis in Sichuan was extremely low during 2004-2018,and the incidence peak of leptospirosis occurred in rice harvesting period.The cases were mainly old farmers,and the high-risk areas were constantly alternating between the Yangtzi River and the Jialing River basin.Both the density and the carriage rate of Leptospira of Apodemusagrarius were low,and the predominant serogroup was Icterohaemorrhagiae.The average positive rate of leptospira antibodies in healthy people was very low.