Baylisascaris procyonis (Ascaridoi-dea: Ascarididae) parasites are facultatively heteroxenous nematodes that are widely distributed in the United States and Canada, where prevalence rates reach 70%–90%. They colonize the small intestine of their nal host, the northern raccoon (Procyon lotor), whose feces can contain up to 25 × 103 eggs/g. Under ideal environmental conditions (100% humidity and 24°C), eggs become infective in soil (1,2). When ingested by other mammalian hosts, third-stage lar-vae can produce pathologic changes called larva migrans, which can lead to chronic neurologic disorders and even death (1,3). B. procyonis parasite infection of humans oc-curs by the fecal–oral route (ingestion of eggs in contami-nated food) (1). Small children are particularly vulnerable through accidental geophagia. Public health concerns arise where raccoon and human populations overlap.
