Altered prevalence of raccoon roundworm (Baylisascaris procyonis) owing to manipulated contact rates of hosts

Baylisasearisprocyonis is a common parasitic nematode of the raccoon Procyon lotor. In intermediate or accidental hosts, including humans, B. procyonis can cause severe disease and mortality, and the parasite is increasingly viewed as an important wildlife conservation and public health concern. The prevalence of B. proeyonis was assessed over a 4-year period in a population of raccoons in a forested region of lower New York. Prevalence ranged from 0% (undetected) to 21%, which was relatively low compared to values reported in other studies from the north-east. During year three of the study, a Subset of the raccoon population was experimentally manipulated through altered resource distribution to enhance the contact of individuals. Within the manipulated subpopulation, prevalence of B. procyonis increased to 54% which was significantly greater than prevalence in the same subpopulation before perturbation or than prevalence among raccoons that were not subject to increased intraspecific contact. These observations suggest that altered resource distributions that directly influence raccoon behaviour may indirectly play a role in the ecology of B. proclyonis.