Raccoon Roundworm

Raccoon Roundworm Eggs in Raccoon Feces
Raccoon Roundworm Eggs in Raccoon Feces

What is Raccoon Roundworm?

Raccoon roundworm is the nematodeBaylisascaris procyonis, which is a parasite of raccoons (Procyon lotor).  The roundworm has been reported in numerous states, but is expected to occur throughout the range of raccoons.  In Florida the roundworm appears to be widespread, but low in prevalence.

How is it transmitted?

Baylisascarisis an intestinal parasite of raccoons.  The adult female worm can produce more than 150,000 eggs in a day, and these are passed out of the raccoon through the feces.  Since a single raccoon may have hundreds of adult worms, that raccoon may shed millions of eggs during a day.  Raccoons often use communal sites, called latrines, to defecate, which leads to a high concentration of eggs in some areas.  The eggs can survive for many years in the environment.  

Once outside of the raccoon's body, the eggs can mature in a few weeks (11 to 14 days) and become larva.  This is the infective stage forBaylisascaris.   As animals eat in areas near raccoon latrines, they may accidentally eat the infective roundworm larvae.  When raccoons eat the larvae, it is returned to their intestinal system, where it finishes developing and starts the life cycle over.  When animals other than raccoons eat the roundworm larvae, it migrates through the tissues of the host, often invading the eyes or brain of the host.  Animals that become sick or die from the roundworm infection may also be eaten by raccoons, which return the larvae to the raccoon's intestines, where the life cycle starts over again. 

What are the impacts to people?

Raccoons often live in close proximity to people.  In urban and suburban areas raccoon latrines can be found in yards under trees, sandboxes, and on decks and patios.   Rarely people, especially small children, may ingest the raccoon roundworm after working or playing in areas that have been contaminated by roundworm eggs.  Other people at risk of infection may include hunters, taxidermists and nuisance wildlife trappers.  Raccoon roundworm infection in humans can cause damage to the central nervous system and other organs and tissues as the larvae migrate through the body and can eventually lead to death. 

What are the impacts to wildlife?

Over 90 species of mammals and birds have been reported as infected with raccoon roundworm, with birds and small mammals being the most susceptible.  Feeding habits and location in areas with large numbers of raccoons may make some species more susceptible to raccoon roundworm infections than other species.  For example, woodrats (Neotoma floridanus) often feed in raccoon latrines and will even carry feces back to their large stick nests, increasing the chance for infection.  While more than 20 species of greatest conservation need could be impacted, some species like the endangered Key Largo woodrat may be at greater risk because of feeding habits and their already low population levels.  

What steps is FWC taking?

Preventing the spread of raccoon roundworm is the most significant way to reduce risk to both humans and wildlife.  FWC is collecting raccoon specimens from around the state to test for the presence of raccoon roundworm. 

What you can do?

  • Do not feed wildlife.  Feeding wildlife can increase the number of raccoons in an area.  
  • Wash your hands after working in the yard.
  • Monitor small children to prevent them from putting dirt in their mouths while playing outside.
  • If you clean up an area that you suspect to be a raccoon latrine, be sure to wear gloves and burn or bury the feces. 
  • Wildlife rehabilitators should take additional precautions. 
  • Dispose of all raccoon feces by burning or burying.
  • Prevent raccoons from coming in contact with each other or other animals in rehabilitative care.
  • Treat raccoons with preventative anthelmintics.
    • Nuisance animal trappers can help prevent the spread
    • Do not relocate raccoons

Additional information:

Centers for Disease Control: http://www.floridahealth.gov/diseases-and-conditions/rabies/

Florida Department of Health: http://www.floridahealth.gov/diseases-and-conditions/diseases-from-animals/_documents/baylisascaris.pdf

FWC Facts:
The Florida Keys: The word "key" comes from the Spanish word cayo, meaning "little island."

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