2017-2022年甘肃省天水市流行性乙型脑炎发病与蚊媒关系研究

Relationship between Japanese encephalitis and mosquito vectors in Tianshui,Gansu Province,China,2017-2022

目的了解甘肃省天水市流行性乙型脑炎(乙脑)的发病和蚊种构成、季节变化规律,分析乙脑发病与蚊媒密度消长的相关性,为有效防控乙脑提供科学依据。方法2017-2022年选定7个生境每月采用诱蚊灯法监测成蚊种类及密度,从中国疾病预防控制信息系统收集乙脑确诊病例(ELISA检测IgM抗体阳性者)信息。采用描述性流行病学方法分析乙脑病例和蚊媒监测结果的分布特征,用简单线性回归模型分析三带喙库蚊密度与乙脑发病之间的关系。结果2017-2022年天水市共报告确诊乙脑病例278例,以2017、2018年发病人数最多,发病时间主要集中在7-9月,占病例总数的98.92%;以成人发病为主,≥20岁病例占95.68%;职业分布主要为农民(88.49%)。蚊媒监测显示,6年间成蚊的构成比差异有统计学意义(χ^(2)=851.227,P<0.001),2017和2018年三带喙库蚊的构成比明显高于2019-2022年;2017-2022年三带喙库蚊平均蚊密度为2.84只(/灯·夜),密度峰值8月最高[9.33只(/灯·夜)],其次为7月[6.02只(/灯·夜)];生态环境中以猪圈、牛圈的三带喙库蚊密度较高,分别为9.50和5.84只(/灯·夜),5年中三带喙库蚊密度与乙脑发病数呈正相关,三带喙库蚊密度可解释乙脑发病约71%的变异。结论三带喙库蚊年度、季节变异性大且与乙脑发病高度相关,持续加强三带喙库蚊为主的蚊媒密度监测,根据蚊虫生活习性及时采取科学的防蚊灭蚊综合措施,对乙脑发病的防控有重要的作用。

Objective To investigate the incidence of Japanese encephalitis(JE)in Tianshui,Gansu Province,China as well as the composition of mosquito species and seasonal changes,and to analyze the correlation between the incidence of JE and the density of mosquito vectors,so as to provide a scientific basis for effective prevention and control of JE.Methods Seven habitats were selected to monitor the species and density of adult mosquitoes by trapping lamps method every month in 2017-2022.The data about confirmed cases of JE(IgM antibody positive by ELISA)were collected from China’s Disease Prevention and Control Information System.The descriptive epidemiological method was used to analyze the distribution characteristics of JE cases and mosquito vector surveillance results in Tianshui from 2017 to 2022,and the simple linear regression model was used to analyze the relationship between the density of Culex tritaeniorhynchus and the incidence of JE.Results From 2017 to 2022,a total of 278 JE cases were reported in Tianshui,with the largest number of JE cases in 2017 and 2018,accounting for 98.92%of the total cases,and the onset time was mainly concentrated in July to September;the cases were mainly found in adults,and 95.68%were aged≥20 years;88.49%of the cases were farmers.Mosquito vector surveillance showed that there was a statistical difference in the composition ratio of adult mosquitoes across the 6 years(χ^(2)=851.227,P<0.001).The composition ratio of Cx.tritaeniorhynchus in 2017 and 2018 was significantly higher than that in 2019-2022.The average density of Cx.tritaeniorhynchus in 2017-2022 was 2.84 mosquitoes/lamp∙night,with the highest density in August(9.33 mosquitoes/lamp∙night),followed by July(6.02 mosquitoes/lamp∙night);Cx.tritaeniorhynchus densities were higher in pigpens and cowsheds,respectively,being 9.50 and 5.84 mosquitoes/lamp∙night.The density of Cx.tritaeniorhynchus was positively correlated with incidence of JE in the 5 years and could explain about 71%of the variation in the incidence of JE.Conclusions Cx.tritaeniorhynchus has large annual and seasonal variability and is highly related to the incidence of JE.Continuously strengthening the monitoring of the density of mosquito vectors dominated by Cx.tritaeniorhynchus,and timely and scientific comprehensive measures to prevent and eliminate mosquitoes according to the living habits of mosquitoes can play important roles in the prevention and control of JE.