On the Edge: Dengue and Climate

描述（由申请人提供）：埃及伊蚊是登革热、黄热病和基孔肯雅热的主要媒介。媒介存在于沿美墨边境延伸的大多数城市社区，但登革热传播仅在德克萨斯州的两个美国边境社区被注意到，特别是布朗斯维尔和拉雷多，德克萨斯州。虽然许多人认为这是边境不同社会因素的结果，但这并不能解释墨西哥北部一些社区缺乏传播，特别是索诺拉诺加利斯。诺加利斯是边境墨西哥一侧的一个大城市，病媒人口众多，不断有来自登革热流行地区的人涌入，但没有记录到当地病例。病媒的存在本身并不足以引起疾病传播；病媒还必须存活足够长的时间，以便吸血并被感染，让寄生虫发育并再次吸血，传播病毒。气候对伊蚊寿命和行为的影响。埃及伊蚊还可能影响该地区登革热传播的风险，该地区处于病毒和媒介的边界。这类地理区域处于疾病和病媒范围的边缘，传染病出现和重新出现的风险最大。我们将评估Ae的相对年龄结构。通过诱捕和分子测定成年伊蚊的年龄，研究了美国南部和索诺拉州九个不同气候城市的埃及伊蚊种群。埃及伊蚊在四个蚊子季节。我们预计，极端干燥和炎热的城市将有更年轻的Ae。蚊数量。报告登革热传播的城市，我们预计有伊蚊。埃及伊蚊在第一次吸血时的平均年龄比没有传播的城市要小。为了确定Ae的年龄。埃及伊蚊种群在更精细的空间尺度上变化，我们将对墨西哥埃莫西约150户家庭的成年人进行抽样；一个有登革热爆发历史的城市。此外，我们将调查家庭中潜在的社会和环境因素，调解气候和寿命之间的关系。我们期望在不同的家庭中发现显著的差异。有老年蚊子的住宅将有更多的植被，蚊子进入的障碍和室内休息场所更少，没有竞争的媒介物种，也没有控制措施。根据前两个目标中收集的信息，我们将构建一个模型来预测Ae扩展的可能性。存活时间足以传播登革热的埃及伊蚊种群，从而改变了登革热传播的风险。我们预计，在气候变化情景下，登革热风险模型将在超过高温和干燥阈值的地区减少，并将在湿度增加的人口中增加。

DESCRIPTION (provided by applicant): Aedes aegypti mosquitoes are the primary vector for dengue, yellow fever and chikungunya. The vector is present in most urban communities stretching along the U.S.-Mexico border yet dengue transmission has only been noted in two U.S. border communities in Texas, notably Brownsville and Laredo, TX. While many argue that this is a result of different social factors across the border, this fails to explain the lack of transmission in some communities in northern Mexico, notably Nogales, Sonora. Nogales is a large urban area on the Mexican side of the border with large vector populations and a constant influx of people from dengue endemic areas yet no local cases have been recorded. Vector presence alone is not sufficient to cause disease transmission; vectors must also survive long enough to blood feed and become infected, have the parasite develop and feed again, transmitting the virus. Climatic influences on the lifespan and behavior of Ae. aegypti may also influence the risk of dengue transmission in this region which lies at the boundary of both virus and vector. Geographic areas such as this, at the edge of the range of disease and vector, are at greatest risk of emergence and reemergence of infectious diseases. We will assess the relative age structure of Ae. aegypti populations in nine cities with varying climates in the southern United States and Sonora, MX by trapping and molecularly determining the ages of adult Ae. aegypti during four mosquito seasons. We expect that cities with extremely dry and hot conditions will have younger Ae. aegypti populations. Cities with reported dengue transmission we expect to have Ae. aegypti that are on average younger when taking their first blood meal than cities without transmission. To determine how the age of Ae. aegypti population vary over a finer spatial scale, we will sample adults in 150 households in Hermosillo, Mexico; a city with a history of dengue outbreaks. Additionally, we will survey the households for potential social and environmental factors that mediate the relationship between climate and longevity. We expect to find significant variability across households. Residences with older mosquitoes will have more vegetation, fewer barriers to mosquito access and indoor resting sites, no competing vector species and no control measures. From the information gathered in the first two objectives, we will construct a model to predict the likelihood of the expansion of Ae. aegypti populations that survive long enough to transmit dengue and thus changes in risk of dengue transmission. We expect that models of risk of dengue under climate change scenarios will decrease in areas that surpass a heat and dryness threshold and will increase in populations with increasing moisture. PUBLIC HEALTH RELEVANCE: This study will advance understanding related to the impact of climate change on the possible emergence of dengue in the southern United States and northern Mexico. A key outcome will be a broader understanding of how climatic changes would impact the longevity of the Aedes aegypti mosquito, a critical component of disease transmission. Risk maps will be generated that depict changes in density of vector's capable of transmission and length of mosquito season.