On the Edge: Dengue and Climate

描述（由申请方提供）：埃及伊蚊是登革热、黄热病和基孔肯雅热的主要传播媒介。这种病媒存在于沿着美国的大多数城市社区-墨西哥边境，但登革热传播仅在德克萨斯州的两个美国边境社区发现，特别是德克萨斯州的布朗斯维尔和拉雷多。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方一些社区，特别是诺加莱斯、索诺拉没有传播的原因。诺加莱斯是边境墨西哥一侧的一个大城市地区，病媒种群众多，来自登革热流行地区的人员不断涌入，但没有记录到当地病例。病媒的存在本身并不足以造成疾病传播;病媒还必须存活足够长的时间，以吸血并被感染，使寄生虫发育并再次进食，传播病毒。气候对Ae的寿命和行为的影响。埃及人也可能影响登革热在该地区传播的风险，因为该地区位于病毒和媒介的边界。像这样的地理区域，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。在美国南部和墨西哥索诺拉的9个不同气候的城市中，通过诱捕和分子测定成年埃及伊蚊的年龄，埃及在四个蚊子季节。我们预计，极端干燥和炎热的城市将有年轻的Ae。埃及人。有登革热传播报告的城市，我们预计会有Ae。第一次吸血的埃及人平均比没有传播的城市年轻。以确定年龄的Ae。埃及人的数量在更精细的空间尺度上变化，我们将在墨西哥埃莫西约的150个家庭中对成年人进行抽样;这是一个有登革热爆发历史的城市。此外，我们还将调查家庭中潜在的社会和环境因素，这些因素介导了气候和寿命之间的关系。我们希望在不同的家庭中发现显著的差异。有老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减少，没有竞争的病媒物种，也没有控制措施。从前两个目标中收集的信息，我们将构建一个模型来预测Ae扩张的可能性。埃及人的生存时间长到足以传播登革热，从而改变了登革热传播的风险。我们预计，气候变化情景下的登革热风险模型将在超过高温和干燥阈值的地区减少，并将随着湿度的增加而增加人口。 公共卫生相关性：这项研究将促进对气候变化对美国南部和北方墨西哥可能出现的登革热的影响的理解。一个关键成果将是更广泛地了解气候变化将如何影响埃及伊蚊的寿命，这是疾病传播的一个关键组成部分。将绘制风险图，描绘能够传播的病媒密度和蚊媒季节长度的变化。

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.