CNH/EID: The Vector Mosquito Aedes aegypti at the Margins: Sensitivity of a Coupled Natural and Human System to Climate Change

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This project will explore the ecology of Aedes (Ae.) aegypti, the mosquito that transmits dengue, yellow fever and chikungunya. We hypothesize that the combined effects of climate variability and changes made by humans to their local environment can influence key aspects of both mosquito ecology and human behavior. Studying this system as a whole will improve our ability to predict risks of mosquito vector and dengue virus exposure and the possible impacts of future climate change. Dengue viruses circulate between mosquitoes and humans, causing an estimated 100 million human dengue infections annually. In the last decade, the Americas have experienced a dramatic increase in severe cases (dengue hemorrhagic fever), with devastating public health consequences. As neither vaccines nor therapeutics are yet available, mosquito control is the main option for preventing and controlling dengue outbreaks. Efforts in this area have been hindered by a poor understanding of the dengue virus transmission system at the interface between its natural and human components. Of particular concern is the potential for dengue fever to expand into areas that are presently outside transmission zones but may become vulnerable under scenarios of future climate change. For example, this potential expansion poses a risk to the ~19 million people in and near Mexico City, a high altitude "island" currently free of dengue but surrounded by dengue virus transmission at lower altitudes. Specific aims of the project are to: (1) determine how weather/climate factors are related to the presence and abundance of disease-carrying mosquitoes, especially by serving as barriers to mosquitoes becoming established in an area; (2) use these results in high-resolution atmospheric models to develop a predictive model for future mosquito range expansion; (3) determine which aspects of human behavior and attributes of man-made environments are most closely related to Ae. aegypti presence and abundance; (4) employ state-of-the-science data assimilation procedures to validate, refine, and define uncertainty in this modeling framework. Key aspects of this coupled natural and human system will be studied along an altitudinal transect in Mexico, ranging from coastal, low-elevation environments with well established vector mosquito populations and intense dengue virus transmission to high-elevation, mountainous areas which currently are free of the mosquito vector and local virus transmission. The team of experts from Mexico and the United States includes climatologists, vector ecologists, modelers and medical anthropologists.The project will contribute essential insights into the ongoing debate about climate change and infectious disease relationships, extending beyond the explicit vector ecology and geographic boundaries of this study. The work will provide quantitative knowledge that can be used to develop novel strategies to control Ae. aegypti in the face of future threats to system resilience. Further, it will provide training for a postdoctoral fellow in climate modeling and spatial risk modeling at both Colorado State University and the National Center for Atmospheric Research and involvement and in situ training of university and secondary school students in data collection. Through "participatory epidemiology", local community members will learn how to use environmental observation and data collection as a means of community empowerment.