Data from: Risk of exposure to potential vector mosquitoes for rural workers in northern Lao PDR

Background: One major consequence of economic development in South-East Asia has been a rapid expansion of rubber plantations in which outbreaks of dengue and malaria have occurred. Here we explored the difference in risk of exposure to dengue, Japanese encephalitis (JE) and malaria vectors between rubber workers and those engaged in traditional forest activities in northern Laos PDR. Methodology/Principal Findings: Adult mosquitoes were collected for nine months in secondary forests, mature and immature rubber plantations and villages. Human behaviour data were collected using rapid participatory rural appraisals and surveys. Exposure risk was assessed by combining vector and human behaviour and calculating the basic reproduction number (R0) in different typologies. Compared to those that stayed in the village, the risk of dengue vector exposure was higher for those that visited secondary forest during the day (odds ratio (OR) 36.0), for those living and working in rubber plantations (OR 16.2) and for those that tapped rubber (OR 3.2). Exposure to JE vectors was also higher in the forest (OR 1.4) and, when working (OR 1.0) and living in the plantations (OR 0.8). Exposure to malaria vectors was greater in the forest (OR 1.3), when working in the plantations (OR 0.89) and lower when living in the plantations (OR 0.6). R0 for dengue was >2.8 for all habitats surveyed, except villages where R0≤0.06. The main malaria vector in all habitats was Anopheles maculatus s.l. in the rainy season and An. minimus s.l. in the dry season. Conclusions/Significance: The highest risk of exposure to vector mosquitoes occurred when people visit natural forests. However, since rubber workers spend long periods in the rubber plantations, their risk of exposure is increased greatly compared to those who temporarily enter natural forests or remain in the village. This study highlights the necessity of broadening mosquito control to include rubber plantations.

研究背景：东南亚经济发展的一项主要后果是橡胶种植园的快速扩张，该区域曾出现登革热与疟疾暴发疫情。本研究针对老挝人民民主共和国（Laos PDR）北部的橡胶工人与从事传统林业活动人员，对比了二者暴露于登革热、日本脑炎（JE）及疟疾媒介的风险差异。
研究方法与主要发现：研究人员在次生林、成熟与幼龄橡胶种植园及村庄中开展了为期9个月的成蚊采集工作；通过快速参与式农村评估（rapid participatory rural appraisals）与问卷调查收集人类行为数据；结合媒介种群与人类行为数据，计算不同生境下的基本再生数（R0），以此评估暴露风险。与留守村庄的人群相比，日间到访次生林的人群（比值比OR=36.0）、在橡胶种植园居住与劳作的人群（OR=16.2）以及橡胶割胶工人（OR=3.2）的登革热媒介暴露风险更高。日本脑炎媒介的暴露风险在森林环境中同样升高（OR=1.4），在种植园劳作时（OR=1.0）及居住于种植园时（OR=0.8）的暴露风险与留守村庄人群无显著差异或略有降低。与留守村庄的人群相比，森林环境中的疟疾媒介暴露风险更高（OR=1.3），在种植园劳作时暴露风险略低（OR=0.89），而居住于种植园时暴露风险更低（OR=0.6）。本次调查的所有生境中，登革热的基本再生数（R0）均大于2.8，仅村庄生境的R0≤0.06。所有生境中的主要疟疾媒介为雨季的斑须按蚊复合群（Anopheles maculatus s.l.）与旱季的微小按蚊复合群（Anopheles minimus s.l.）。
研究结论与意义：人群暴露于病媒蚊虫的最高风险出现在到访天然森林之时。但由于橡胶工人需长期在橡胶种植园劳作，与临时进入天然森林或留守村庄的人群相比，其媒介暴露风险会显著升高。本研究凸显了将蚊虫防控范围拓展至橡胶种植园的必要性。