Land-use effects on prevalence of raccoon roundworm (Baylisascaris procyonis)

The raccoon (Procyon lotor) is the definitive host of Baylisascaris procyonis, a large intestinal roundworm that is zoontic and call result ill fatal or severe central nervons system disease in young children. Prevalence of infection among raccoon population often is high, and ill the midwestern United States, B. procyonis has been reported ill 68-82% of raccoons. Raccoon populations have increased in response to changes ill human land use, and often reach higher densities ill urban mid suburban landscapes than rural landscape's. However, shifts in foraging behavior among urban raccoons could impact the transmission of B. procyonis if small vertebrate intermediate hosts are not a significant part of the raccoon diet. The objective of this study was to compare prevalence of B. procyonis infection between urban and rural raccoon populations oil a regional scale. Necropsy was done oil 204 raccoons collected from September through February during 2000-2005 from seven states across the Midwest (regional sample). Baylisascaris procyonis was found in 54% of examined raccoons. Prevalence differed between land-use types (chi(2) = 11.56, df = 1, P=0.0007), Bind was higher among animals collected from rural locations (65%) than those collected ill urban locations (41%). Intensity of infection also differed (F=5.52, df=1, P=0.02), with rural raccoons having greater worm burdens ((x) over bar =29.63+/36.42) than urban raccoons ((x) over bar =13.85+/-18.47). Despite high densities of raccoons ill urban landscapes, fewer urban raccoons were infected with B. procyonis, suggesting decreased dependence oil intermediate hosts as a food source. This possible explanation was supported by a similar trend ill prevalence among subsamples of raccoons collected from three Chicago-area populations (local samples) with differing levels of urbanization, population densities, and foraging behavior that bad been intensively monitered during 1995-2002. Decreased transmission of B. procyonis ill urban landscapes may be due to decreased predation of intermediate hosts, and contact of juvenile raccoons with B. procyonis eggs may be an important factor in maintaining infections within such populations.