Molecular population genetics and evolution of two infectious disease systems: Human malaria and lyme disease

Many questions in the study of infectious and parasitic diseases are best explored by application of the principles of evolutionary biology; which contributes greatly to our understanding of infectious disease in two principle ways, which differ primarily in scale. The first approach is based upon a population-minded ratiocination. By understanding the innate mechanisms by which pathogen populations generate and maintain genetic diversity, we can better determine the risk of resistance to chemotherapeutic treatment, and better assess the sustainable efficacy of vaccines targeting particular epitopes. The second approach is rooted in understanding the processes of speciation. By examining the phylogenetic foundations of parasites and their hosts, we can determine the broader history of the association between the organisms requisite to the particular parasite life cycle. This allows for determining the origin of incipient human disease, and may aid in proactive endeavors to identify future risk. I examine several evolutionary aspects of two distinct parasite systems both of which involve an arthropod vector in their respective transmission cycle. The first is one of four causative agents of human malaria which kills over 2 million people annually and threatens the health of one-sixth of the world population. The second is Lyme disease which, though certainly less lethal than malaria, is the single most commonly reported arthropod disease in North America.