What is Raccoon Roundworm?
Raccoon roundworm is the nematodeBaylisascaris procyonis, which
is a parasite of raccoons (Procyon lotor). The roundworm
occurs in raccoon populations throughout the northeast,
mid-Atlantic, and mid-western United States. It was recently
discovered in free-ranging raccoons in Wakulla, Leon, and Broward
counties here in Florida.
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
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
- Wildlife rehabilitators should take additional
- 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
Centers for Disease Control:
Florida Department of Health: