Abstract: Objective To investigate the composition and dynamic change of mosquito species in Longnan, Gansu province, China and analyze the correlation between Japanese encephalitis (JE) onset and Culex tritaeniorhynchus, and to provide a scientific basis for JE prevention and control. Methods The distribution characteristics of JE cases and mosquito vector surveillance results were analyzed using descriptive epidemiology. The relationship between JE incidence and Cx. tritaeniorhynchus density was determined by linear correlation. Results A total of 215 cases of JE were reported in Longnan between 2017 and 2018, and the mean annual incidence rate was 4.11/100 000. JE onset occurred mostly between July and September. JE was observed mainly in adults (87.44% of individuals ≥ 20 years old) and in peasants from rural areas (91.16%). Mosquito vector surveillance results showed that Cx. pipiens pallens was the dominant female mosquito species that was entrapped, followed by Cx. tritaeniorhynchus. In addition, the dominant mosquito species varied with habitat. Culex pipiens pallens was the dominant species in residential areas, parks, hospitals, and peasant households (>75.00%), whereas Cx. tritaeniorhynchus was common in livestock sheds (61.51%) and peasant households (9.85%). In 2017 and 2017-2018, the monthly monitored density of Cx. tritaeniorhynchus was positively correlated with the number of JE cases one month later (r=0.983, P=0.001; r=0.937, P=0.006). Conclusion The distribution, density time, and seasonal variation of Cx. tritaeniorhynchus are closely related to JE onset. Understanding the correlation between the change in Cx. tritaeniorhynchus density and JE onset will provide insights into the early warning for JE prevention and control.

Key words: Japanese encephalitis, Epidemiological characteristics, Culex tritaeniorhynchus

摘要： 目的 了解陇南市蚊种构成和动态变化，分析流行性乙型脑炎（乙脑）发病与三带喙库蚊的相关性，为乙脑防控提供科学依据。方法 采用描述性流行病学方法分析陇南市2017-2018年乙脑病例和蚊媒监测结果的分布特征，用线性相关分析乙脑发病与三带喙库蚊密度之间的关系。结果 2017-2018年陇南市累计报告乙脑病例215例，年平均报告发病率为4.11/10万；发病时间主要集中在7-9月，呈现以成人为主的发病特点，≥ 20岁病例占87.44%，职业以农民为主，农村病例占91.16%；蚊媒监测显示，捕获雌蚊以淡色库蚊为优势蚊种，其次是三带喙库蚊；不同生境蚊种优势种不同，居民区、公园、医院和农户以淡色库蚊为优势种，占捕获总数的75.00%以上，三带喙库蚊在牲畜棚所占比例为61.51%，其次是农户为9.85%；2017及2017-2018年（将2017和2018年对应月份的乙脑发病数和蚊密度合并）三带喙库蚊月监测密度与滞后1个月的乙脑发病数呈正相关（r=0.983，P=0.001；r=0.937，P=0.006）。结论 三带喙库蚊的分布、密度、季节变化与乙脑发病密切相关；三带喙库蚊密度变化可为乙脑防控工作提供预警指示。

关键词: 流行性乙型脑炎, 流行病学, 三带喙库蚊