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Raccoon Roundworm

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Raccoon roundworm eggs in raccoon feces

What is Raccoon Roundworm?

Raccoon roundworm is the nematode Baylisascaris procyonis, an intestinal parasite of raccoons (Procyon lotor).  The roundworm has been reported in numerous states, and is expected to occur wherever raccoons range.  In Florida the roundworm appears to be widespread, but low in prevalence.

How is it transmitted?

Each adult female worm can produce more than 150,000 eggs in a day.  Because a raccoon may have hundreds of adult worms, a single raccoon may shed millions of eggs in its feces each day.  Raccoons often defecate in communal sites, called latrines, which leads to high concentrations of eggs, and the eggs can survive for many years in the environment.    

Once outside of the raccoon's body, the eggs can become infectious in 2-4 weeks. As animals eat near raccoon latrines, they may eat infectious eggs. When raccoons ingest infectious eggs, the eggs develop into larvae in the intestine, mature to adults, and start the life cycle over.  When animals other than raccoons eat infectious roundworm eggs, the parasites migrate through the tissues of the body, often invading the eyes or brain.  Animals that become sick or die from roundworm infection may also be eaten by raccoons, which returns the larvae to the raccoon's intestines, where the life cycle starts over again. 

What are the impacts to people?

Raccoons often live near people.  In urban and suburban areas raccoon latrines can be found in yards under trees, in sandboxes, and on decks and patios. People may ingest raccoon roundworm after working or playing in areas that have been contaminated with raccoon feces. Young children are at high risk because they are more likely to put contaminated fingers, soil or other objects into their mouths. Other people at risk of infection 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. 

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 may make some species more susceptible to raccoon roundworm infections.  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