This project examines how malaria spreads over space and through time. The investigators will measure the movement of genetic markers (gene flow) to understand the factors that prevent transmission (barriers) or promote the disease (corridors). Barriers can be caused by humans, such as malaria-control programs, or they can be natural, such as mountains that restrict mosquito vector habitat because of cool temperatures. Corridors can also be created by humans, such as roads, or they can be natural, such as rivers that channel the movement of mosquitoes. To achieve the goals of this proposal, the researchers will use data and specimens from the Democratic Republic of Congo (DRC), a country with high but spatially variable malaria endemicity. The investigators will analyze information based on DNA extracted from dried blood spots collected through large population-based demographic and health surveys in 2007 and 2013. These data were collected in geocoded survey clusters. The researchers will measure relationships between genetic and geographic distance of Plasmodium falciparum malaria parasites in different areas of the country. They also will identify factors that prevent or promote diffusion of drug-sensitive and drug-resistant malaria parasites. They hypothesize that malaria control programs, transportation routes, and human migration patterns affect diffusion of drug-resistant malaria.
This proposal has significant intellectual merit because it combines spatial theory and methods, landscape genetics, and high-throughput molecular tools to provide information about how drug resistance diffuses over space and time. The results of this project will have positive broader impacts in the DRC and in other malaria-endemic countries because they will help target and evaluate interventions. Malaria represents a massive public health problem, especially in the DRC, where almost one-third of all adults were found to be infected in the 2007 national survey. The identification of population and ecological drivers of malaria diffusion in the DRC could impact malaria-control efforts throughout the developing world. The project will serve as a prototype for other malaria-endemic countries, which could use their demographic and health survey dried blood spots in similar ways. The project will provide education and training opportunities for students in medical geography and spatial and molecular epidemiology.
