云南景洪市蚊虫季节消长与乙型脑炎流行关系研究

Relationship between the seasonal fluctuation of mosquito populations and the epidemic of Japanese encephalitis in Jinghong County, Yunnan Provence

为掌握云南景洪市蚊虫季节消长特点及其与乙型脑炎流行的关系，为该疾病防控提供有效依据，2007年10月至2008年9月本研究在云南景洪市普文镇畜圈和人房每月采用诱蚊灯方法通宵捕蚊，对采获的蚊虫使用白纹伊蚊C6／36细胞培养法分离乙脑病毒，并对分离到的病毒进行分子生物学鉴定。收集2007～2008年景洪市乙脑疫情资料进行乙脑病例按月分布分析。2007年10月至2008年9月共采集4属18种18194只蚊虫，三带喙库蚊占82．79％（15064／18194），其中，在畜圈和人房采集的蚊虫均以三带喙库蚊构成比最高，分别为83．44％（14942／17908）和42．66％（122／286）。2007和2008年景洪市共报告乙脑病例50例，在三带喙库蚊密度高峰月份（5月）开始出现乙脑病例，乙脑病例高峰月份（6月）比三带喙库蚊密度高峰晚1个月出现。从捕获的三带喙库蚊和中华按蚊中共分离到5株具有细胞病变的样本，经乙脑病毒RT．PCR检测、BLAST序列比对及进化树分析均属于基因1型乙型脑炎病毒。其中，在流行季节高峰前的5月，从三带喙库蚊中分离到1株乙脑病毒；在流行季节后采集的三带喙库蚊和中华按蚊中各分离到3株和1株乙脑病毒。本研究结果表明，乙脑发病与三带喙库蚊的季节消长密切相关，三带喙库蚊是当地主要传播媒介，景洪市近年乙型脑炎可能主要是基因1型乙脑病毒流行。结果提示当地防疫部门应在流行高峰前开展防蚊灭蚊措施，特别是加强乙脑疫苗接种工作，在流行季节（5～7月）积极开展病例监测。

To investigate the relationship between the seasonal fluctuation of mosquito populations and the epidemic of Japanese encephalitis （JE） in Jinghong County of Yunnan province, and provide an effective basis for JE control, a field investigation was conducted from 2007 to 2008 on the seasonal fluctuation of mosquitoes. Viruses were isolated from collected mosquitoes and identified, and the data of JE cases were simuhaneously collected and analyzed. A total of 17 908 mosquitoes belonging to 4 Genera and 18 species were collected with Culex tritaeniorhynchus and Anopheles sinensis as the dominant species in livestock shelters and human houses. The seasonal distribution of JE cases closely coincided with the seasonal fluctuation of Cx. tritaeniorhynchus. A strain of genotype 1 JEV was isolated from Cx. tritaeniorhynchus collected before the seasonal peak of JE incidence and four strains from Cx. tritaeniorhynchus and Anopheles sinensis collected after the seasonal peak of JE prevalence. The result showed that Cx. tritaeniorhynchus was the main species of JEV vector, and the local pathogen of JE was probably genotype 1 JEV. Vector surveillance in JE incidental areas for monitoring vector population should be build up for timely implementation of intervention methods. Vector mosquito control and JEV vaccination should be initiated and enhanced before JE prevalence.