Understanding how temperature affects disease-causing organisms and the mosquitoes that carry them is critical for predicting and responding to future changes in disease risk. Many of the world's most devastating and neglected infectious diseases require mosquitoes and other insects for transmission between people. Malaria kills over 650,000 people each year, mostly children in sub-Saharan Africa, and pathogens like West Nile virus, dengue virus, and chikungunya virus are on the rise in both North America and the tropics. Mosquitoes and the pathogens they carry are sensitive to the environment, so changes in climate, particularly temperature, affect disease risk both in the tropics and in temperate areas. This award supports research to measure the effect of temperature on 13 different pathogens that use mosquitoes and flies for transmission, and the capacity for two common mosquitoes in the Americas to adapt to different temperature conditions. In addition, this work will support STEM education through training in science and math with a focus on under-represented groups, and will contribute publicly available data that can be used by other researchers and public health professionals.
The goal of this project is to develop a general framework for predicting the temperature sensitivity of vector transmission. This work addresses three main questions: (1) How does vector-borne pathogen transmission respond to temperature? (2) How important is the influence of temperature, relative to other factors, on transmission in the field? (3) Can such transmission adapt to local temperature regimes? The research will develop temperature-sensitive transmission models and fit them with data from the existing literature for 13 vector-borne diseases: vivax malaria, trypanosomiasis, dengue, chikungunya, yellow fever, West Nile, Eastern equine encephalitis, Western equine encephalitis, St. Louis encephalitis, Rift Valley fever, Ockelbo (Sindbis) disease, Ross River fever, and bluetongue. Laboratory experiments will measure local thermal adaptation of Aedes aegypti and Ae. albopictus mosquitoes, which transmit dengue and other viruses, from across their geographic and temperature ranges. In tandem, the research will develop and test theory on how vectors and parasites respond to temperature based on theory from physiological ecology. New local-scale data collected in Ecuador on transmission risk, dengue cases, climate, and other social and economic factors will be used to validate the model predictions. Complementing these local-scale data, the research will develop a global database on field transmission from the existing literature, along with climatic and socioeconomic information. Together, these field data will test the accuracy of the transmission models and assess the relative importance of temperature for transmission at scales from neighborhood to continent.
