Raccoons (Procyon lotor) are the final host for raccoon roundworms (Baylisascaris procyonis). Raccoon roundworm is the leading cause of a dangerous neurological disease, known as larva migrans encephalopathy. Phylogenetic trees illustrate co-evolutionary events between species living in a symbiotic relationship with each other. Throughout the coevolution of host and parasite, many aspects of a population affect the way the members interact with one another and with symbiotic species. In order to evaluate the relationship between host and parasite in regards to diet, we isolated DNA from intestinal wall tissue, amplified a portion of exon 2 from MHC II, and sent our samples to Ohio State University for sequencing. We calculated heterozygosities for the nine townships we surveyed. We used a chi-squared test for equality of distributions to test whether raccoons from townships with above 60% prevalence have different heterozygosity for this locus than other raccoons. These data will help us to understand the relationship between raccoons and raccoon roundworm