Redefining thermal suitability for urban malaria transmission in the context of humidity

修改项目摘要/摘要部分 随着城市环境成为地球上增长最快的景观，过去几十年来，适应城市的蚊子传播病媒疾病的情况显著增加。城市病媒包括斯氏按蚊，这种蚊子是南亚城市疟疾的罪魁祸首。要在南亚消灭疟疾，并做好准备防止其进一步蔓延到非洲，就必须在城市采取有效行动防治这一疾病。我们知道温度对疟疾传播有很强的非线性影响。虽然相对湿度对疟疾流行病学也有重要影响，但其对传播的定量影响却远远没有得到充分研究，而且往往被视为与温度无关。由于这些关系目前还没有得到很好的理解，我们预测城市环境中疟疾的出现、传播和控制的能力有限。我们的总体假设是，湿度通过改变温度-传播关系来影响城市疟疾传播。此外，纳入湿度的影响将改善对疟疾传播的预测以及传播的时间和空间模型中疟疾风险热点的预测。我们拟议的研究将通过以下具体目标来解决这一知识差距。 目的1探讨湿度对温度-疟疾传播关系的影响。将进行全面的实验，以确定相对湿度和温度对蚊子和疟疾生活史与传播有关的特征的影响。这些实验将在印度的一组条件下使用当地媒介和当地恶性疟原虫和间日疟原虫菌株进行验证。这些机制关系将被纳入目标2和3中的疟疾流行病学时空模型。目标2将制定和参数化一个时间耦合的人-蚊传播模型，用于预测疟疾发病率和病媒丰度的季节和年际变化。目标3将建立一个空间模型，通过利用气象观测和城市土地覆盖数据来预测城市环境中的传播风险和发病率，绘制疟疾传播的环境适宜性地图。然后，适宜性地图将与人口密度和社会经济因素叠加，以预测传播热点。印度的两个城市，苏拉特和阿赫梅达巴德，在年平均相对湿度方面存在显著差异，在过去二十年中一直保持着广泛的疟疾监测方案。这两个城市将提供对比的机会，以测试目标1中的气候-特征关系改善城市疟疾传播模式的能力。主要成果包括基于蚊子生物学的城市疟疾环境流行病学的改进概念框架，以及应用这些知识预测疾病传播的新建模方法。预测即将到来的异常季节并确定热点将加强有针对性的公共卫生干预。

Modified Project Summary/Abstract Section With urban environments the fastest growing landscapes on the planet, transmission of vector-borne diseases by urban adapted mosquitoes has increased markedly over the past several decades. Urban vectors include Anopheles stephensi, the mosquito responsible for urban malaria across South Asia. Elimination of malaria in South Asia, and preparedness against its further expansion into Africa, hinges on effective action against the disease in cities. We know temperature has strong, non-linear effects on malaria transmission. Although relative humidity also has important effects on malaria epidemiology, its quantitative effects on transmission are vastly understudied and often treated as independent from temperature. Because these relationships are currently not well understood, we have limited capacity to predict the emergence, spread, and control of malaria in urban environments. Our overarching hypothesis is that humidity affects urban malaria transmission by modifying the temperature-transmission relationship. Further, incorporating the effect of humidity will improve predictions of malaria transmission and hot spots of malaria risk in both temporal and spatial models of transmission. Our proposed research will address this knowledge gap through the following specific aims. Aim 1 will investigate the effects of humidity on the temperature-malaria transmission relationship. Comprehensive experiments will be conducted to characterize the effects of both relative humidity and temperature on mosquito and malaria life history traits relevant for transmission. These experiments will be validated over a subset of conditions in India with the local vector and local strains of P. falciparum and P. vivax. These mechanistic relationships will then be integrated into temporal and spatial models of malaria epidemiology in Aims 2 and 3. Aim 2 will formulate and parameterize a temporal coupled human- mosquito transmission model used to predict the seasonal and interannual variation in malaria incidence and vector abundance. Aim 3 will implement a spatial model to predict transmission risk and incidence across urban environments by using meteorological observations with urban land cover data to map environmental suitability for malaria transmission. Suitability maps will then be overlaid with population density and socio- economic factors to predict hotspots for transmission. Two cities in India, Surat and Ahmedabad, experience notable differences in mean annual relative humidity and have maintained extensive surveillance malaria programs over the last two decades. These two cities will provide contrasting opportunities to test the ability of the climate-trait relationships from Aim 1 to improve transmission models of urban malaria. Major outcomes include an improved conceptual framework for the environmental epidemiology of urban malaria based on mosquito biology, and new modeling approaches that apply this knowledge to make predictions of disease transmission. Prediction of upcoming anomalous seasons combined with identification of hotspots will enhance targeted public health intervention.