B procyonis, (ie, raccoon roundworm) is common in raccoons and is a cause of rare but potentially devastating neural larva migrans in humans. Raccoons are the natural host of this large nematode, and shedding rates can be up to 92% in healthy raccoons.1-4 Infected raccoons can shed millions of eggs per day in feces, and as raccoons tend to defecate in specific areas (raccoon latrines), some environmental sites can become extremely contaminated.5,6 As with other roundworms, B procyonis eggs are not immediately infective and second-stage larvae must develop in eggs in the environment over 2 to 4 weeks.7 Infection can occur after ingestion of infective eggs.
Related Article: Baylisascaris Expansion—A Zoonotic Threat
Neural larva migrans associated with Baylisascaris spp can occur following ingestion of infective eggs by humans (and many other species, including dogs8,9), with larval migration through brain tissue. Cases reported in humans have mostly involved young children and children with developmental delay, groups that may be more prone to pica or geophagia.10,11 While ingestion does not necessarily result in disease, prophylactic treatment of individuals exposed to contaminated feces has been recommended because of potential risk for severe disease.12