Affiliation: College of Arts and Sciences, Department of Geography
Roughly 40% of the world's population lives in areas where they are at risk of malaria infection. In the last 15 years, the global health community has made considerable progress in reducing transmission. Despite this progress, a number of challenges to further reductions remain. This dissertation addresses three such challenges. First, I focus on the ecology that serves as a backdrop to transmission, and focus on the role agriculture may play. In doing so, I attempt to understand how agriculture affects both mosquito behavior, as well as malaria risk in under-5 children in the Democratic Republic of Congo (DRC), a country with one of the world's highest malaria burdens. My findings from this work suggest that increasing exposure to agriculture is associated with increased indoor biting among Anopheles gambiae mosquitoes, which may be the mechanism driving the observed association between agriculture and increased malaria risk. Second, I turn to address insecticide resistance, which may undermine the contributions that bed nets have in reducing transmission. One challenge in monitoring insecticide resistance is the difficulty in obtaining representative samples of mosquitoes. I make some progress in overcoming this limitation using population-based survey data collected from 2009-2016 in 21 countries across sub-Saharan Africa, and find that the effects of bed nets treated with different insecticides vary considerably, and that certain countries need to transition away from using certain insecticides. Finally, I attempt to understand how malaria spreads. To do so, I leverage genetic data on the Plasmodium falciaprum malaria parasite from 28 neutral microsatellite markers drawn from malaria-infected children living in the DRC. I consider different population genetics tools to identify whether or not the malaria parasite population can be classied into smaller subpopulations, whether or not there is evidence of isoloation-by-distance, and if there appears to be gene flow between geographically and economically proximate regions. My results indicate that the malaria parasite population in DRC is best characterized as single population with weak evidence of isolation-by-distance, with no strong evidence of gene flow or barriers to it. However, outliers were observed along DRC's border.