UC Irvine

During a time of intensive antimalarial campaigns, it is crucial to understand the effects these campaigns have on the population genetics of malaria parasites and mosquitoes, particularly with respect to genes associated with drug and insecticide resistance. In addition, as countries approach malaria elimination, it will be critically important to understand the underlying factors that cause malaria epidemics or help to sustain malaria transmission in order to effectively control malaria and achieve elimination. Therefore, my dissertation research aims to A) evaluate the impact that public health interventions have on the population genetics of malaria parasites and mosquitoes; and B) assess the relative impact that key ecological factors have on the dispersal, measured through gene flow, of malaria parasites and vectors. To address these aims, I collected malaria parasite and mosquito samples in Kenya and genotyped them for molecular markers associated with drug and insecticide resistance, as well as neutral markers to infer gene flow. I tested the link between key ecological factors (temperature, precipitation, vegetation index, topographic wetness index, human population density, and distance to roads) and spatial genetic structure between populations using landscape genetic analytic methods. I found a recent increase in drug resistance markers associated with the antimalarial drug used to prevent malaria in pregnancy, as well as an increase in polymorphisms associated with increased tolerance to the partner drug of the first-line treatment for malaria. I found a key mutation to be associated with insecticide resistance in Anopheles arabiensis in Kenya, as well as that this mutation is common throughout Western Kenya. Finally, I found that high human population density promotes dispersal of An. gambiae s.s., high temperatures and low vegetation indices promote dispersal of An. arabiensis, and that physical barriers to human travel, such as lakes, may prevent dispersal of P. falciparum in Kenya. These findings allow us to identify areas susceptible to the introduction of malaria parasites and malaria vectors, as well as drug and insecticide resistance.