Water and Disease

The Eltahir Research Group applies knowledge of hydrology and climate systems to problems of disease transmission, particularly in Africa. Our primary focus has been on malaria, a mosquito-borne disease that affects an estimated 250 million people per year.

A main initiative of the Eltahir Group has been the development of a detailed agent-based model, HYDREMATS, which provides a mechanistic link between environmental factors and malaria transmission at the village scale. Current research involves the application of this model in areas including short-term forecasts of malaria epidemics, management of hydropower dams to minimize vector habitat, and assessing the impacts of climate change on malaria. A version of HYDREMATS is being adapted to simulate Dengue Fever, another important vector-borne illness.

Field activities are an important component of this research area, and we maintain research sites in Niger and Ethiopia.

Hydrology and Malaria – Environmental Management in Ethiopia -- Climate is known to be a strong influence on malaria incidence. But other environmental factors, such as the existence and management of a reservoir, also contribute to malaria transmission. In 2011, the Eltahir Research Group launched a new project based in Ethiopia with two field sites: one adjacent to the Koka Reservoir and the other 10 km from the reservoir. A previous study found that malaria incidence in populations living within 1 km of the Koka reservoir was nearly 20 times greater than for those living 5 to 9 km away. Due to the need for additional energy sources and irrigation water, Ethiopia is now promoting new constructions of dams and reservoirs. Therefore the goals of this research project are to investigate the impact of these environmental factors on mosquito productivity and to help inform good decision-making for reservoir management in an effort to reduce local malaria.

Climate Change and Malaria in West Africa -- Malaria transmission is closely tied to climate. In West Africa, mosquito populations depend on the availability of water pools for breeding. The presence and persistence of these pools are tied to the region’s hydrology, as they are formed by excess rainfall and depleted by evaporation and infiltration into the ground. Temperature also plays an important role in malaria transmission, affecting the lifespan of the adult mosquito, the development rates of mosquito larvae, and the incubation period of the malaria parasite within the mosquito. In this project, we are using predictions of these climatic variables to look at how the environmental suitability for malaria transmission will change as temperatures rise and the distribution of rainfall is altered. We use HYDREMATS to simulate transmission under current and future climates and identify areas that may be especially vulnerable to increases in transmission, as well as areas where transmission is expected to decrease.

Climate Change and Resurgence of Mosquito-borne Viral Diseases -- Mosquitoes can carry many viral diseases, such as dengue fever, West Nile virus and Rift Valley fever. Dengue is transmitted mainly by Aedes species in the tropics. West Nile virus is transmitted by Culex species. In the last decade, there has been an increase in the frequency and intensity of mosquito epidemics. Both climate and societal factors are important for explaining these changes in epidemics. Because mosquito species occupy different ecological niches, they exhibit differential sensitivity to climate change. This project aims to improve forecasts of mosquito-borne disease epidemics and aid in developing the most appropriate management strategies for a given context.