Raccoons and Roundworm

Raccoon Roundworms (Baylisascaris procyonis)

Recently, a little boy in West Seattle was diagnosed with encephalomyelitis (swelling of the brain) caused by migration of raccoon round worms (Baylisacaris).  This can be a very serious condition.  Fortunately, the story on the West Seattle Blog says the boy is responding to treatment.

The health of the raccoon is not typically affected by the presence of this worm but when other species are exposed, the worm can spread into unusual places.   The larva can migrate into abdominal organs, the eye, and the nervous system.  This condition can occur in in over 90 species of birds and mammals, including dogs, cats, and rabbits.

People and animals may be exposed to this worm in raccoon feces.  Raccoons use a common area to defecate, referred to as a “latrine”.  These latrines may be located at the base of trees, decks or patios, roofs, attics, or horizontal surfaces such as fallen logs or stumps.  Exposure to raccoon roundworm may occur in these areas or raccoon dens. 

This potentially lethal condition is rare but does obviously occur.  Prevention in people relies on handwashing and the removal and avoidance of raccoon latrines (consult the CDC or public health at www.cdc.gov/parasites/baylisascaris/resources/raccoonlatrines.pdf on how this is done safely).

For dogs, cats, and rabbits, Baylisascaris infection is completely preventable.  Good quality flea products that also control parasites prevent this disease.  Topical Revolution used monthly will prevent raccoon roundworm in all three species.  Dogs may also take monthly oral Interceptor or Trifexis to prevent parasitism including Baylisascaris.  These products also prevent heartworm and intestinal parasites that animals are often exposed to on common grass areas.  Most over the counter flea control products do not prevent parasite infections and will not protect against Baylisascaris.

(Note: Because Revolution and Trifexis are prescriptions, your dog or cat must be up to date on their wellness exam before we can sell these products).

Please feel free to contact us if you have any questions about this very preventable disease.


Timothy R Kraabel, DVM, DABVP (Canine/Feline Practice)

Vice President, American Board of Veterinary Practitioners