How Do You Get Roundworm Parasites From Pets or Wildlife?
The Sources of Raccoon Roundworm
Information About Roundworm Exposure and Symptoms in Humans
In my early 20s, I worked at a wildlife rehabilitation facility. I absolutely loved it and was especially fond of working with predatory mammals. I had completed my rabies vaccine series and had quite a bit of animal husbandry experience beforehand. I was often assigned to the raccoons. These duties included tube feeding orphaned babies, cleaning individual crates, medicating, and cleaning outdoor enclosures.
One thing we had to be really careful of when cleaning and handling objects and raccoon enclosures was roundworm. I wore gloves, a mask, eye protection (when spraying with a hose), and booties over my shoes. We also used a bleach bath to soak the bottoms of our shoes.
Raccoon roundworm can be acquired from an environment if safety precautions are not taken. So, in order to be safe, I figured I'd do some research to share with the public.
Raccoon roundworm or the Baylisascaris procyonis parasite is different but similar to the canine roundworm or Toxocara canis. Canine roundworm can be cleared with routine prevention whereas raccoon roundworm cases serious neurological symptoms in dogs, humans, etc.
What Is Roundworm?
Raccoons are a definitive host of Baylisascaris procyonis, a parasitic roundworm of zoonotic potential; zoonosis implies the ability to infest humans. Raccoons are peridomestic (habituated to people) and therefore carry the parasite in close proximity to humans, dogs, and cats. Birds and small mammals act as intermediate hosts for raccoon roundworm as well humans. B. procyonis, however, cannot complete its life cycle in the human body.
Note: Infestation is generally used to refer to disease-causing parasites whereas infection is used to refer to disease-causing microorganisms (bacteria, viruses).
When Am I at Risk?
Eggs take 2-4 weeks to embryonate which is when they are most dangerous to humans.
Where Is Roundworm Found?
Roundworm is found throughout the United States (North America), Europe, and Japan—specifically the midwestern and northeastern states and the west coast. It is not commonly found in the southern states.
Where Do Raccoons Like to Live?
Raccoons are a species well-adapted to urban, suburban, and rural settings. They often scavenge for food sourced from garbage cans, bird feeders, and pet food. Raccoons seek out:
- wooden decks
Because raccoons seek out human-made constructions for residency, this puts them in proximity to humans and canine companions.
Did You Know?
Some 43% of raccoon stomach contents are found to contain pet food (Gavin).
Sources of Contamination
Raccoons take to latrines (the deposit and accumulation of feces and urine). Raccoon feces are dark, tube-shaped, and have a pungent odor. The feces contain bones, fruits, vegetables, and scavenged bits of garbage.
How Can You Get Roundworm From Your Pets?
Young children are particularly at risk of an infestation as are dogs. Soil, water, and objects that are contaminated with fecal material and roundworm eggs are direct sources. Ingestion is the most common method of transmission via hand-to-mouth (or the consumption of contaminated soil, fruits, and vegetables).
The eggs are hardy and can survive in the environment and stay viable and infective for years. Eggs take 2-4 weeks to embyronate and become infective. 20,000 to 26,000 eggs are shed in each gram of feces (in the millions daily).
What If My Dog Has Roundworm?
Dogs can be infected and not show signs. Deworming of your pet is necessary for prevention. Common dewormers include pyrantel pamoate and fenbendazole. Dogs can shed the eggs or harbor a patent infestation (sexually mature adult infestations). Dogs are also indiscriminate defecators, so their stool may be distributed throughout the yard and pose a risk to humans.
What Are the Signs and Symptoms of Roundworm in Humans?
The roundworm is known to migrate (neural larva migrans). In humans, the large and hardy worms hatch in the small intestine, penetrate through the lungs and enter systemic circulation via the left side of the heart. The liver, heart, lungs, brain, eyes, spinal cord, and other organ tissues are concurrently damaged. Dogs are infected in a similar manner. Common symptoms in humans include:
- hepatomegaly (enlarged liver)
- coordination issues
- muscle spasms
- lung complications (cough, chest pain)
- photophobia, retinitis, blindness
- eventual comatose
Host inflammation does little to protect or cure the infestation. The larger a load of ingested embryonated eggs, the more dangerous the infestation, thus leading to permanent disability and death.
Signs of infestation are based on the load ingested and can take one to four weeks to present.
- In the raccoon: Infestation in the raccoon is subclinical (the adult, tan-colored worms are confined to the small intestine).
- In the human: Infestation in humans can be devastating. The roundworm migrates ocularly, viscerally, and neurally. Central nervous tissue is invaded by the growth of larvae and neurologic survivors have not been documented. Infestation in infants/children are fatal.
How Is Roundworm Diagnosed in Humans?
Early treatment is necessary and diagnosis is difficult; a commercially available serological test does not exist. Other diagnostic methods include:
- positive antibody titers (testing of CSF and serum)
- ocular diagnosis may occur as worms migrate into the eye
- neuroimaging (an MRI may be used to detect white matter abnormalities)
How Is Roundworm Treated?
Prevention is key. A broad-spectrum anthelmintic may be administered. These include:
- albendazole treatment
- corticosteroids used in conjunction with albendazole
Raccoon extraction should be handled by a professional using humane methods. The removal of raccoon waste is also best handled by a professional due to the high risk of zoonotic disease. Do not risk your healthy and safety.
How to Get Rid of Raccoon Waste in the Yard
Remove the aforementioned habitats (wood piles, etc.) and prevent access to food sources and water near public areas. If you come across a potential raccoon latrine or find raccoon feces, remove the feces as soon as possible (2-4 weeks needed for eggs to become infective).
Burn, bury, scorch (controlled propane torch), or scour (with boiling water) any contaminated surfaces. Wear gloves, disposable booties, rubber boots, avoid creating dust, and wear an N95 respirator. Decontaminating sites for canine companions and humans alike is the best method of prevention.
Video: Raccoon Roundworm
- Gavin, Patrick J., and Kevin R. Kazacos, Stanford T. Shulman. “Baylisascariasis.” Clinical Microbiology Reviews 18.4 (2005): 703–718. Accessed 9 March 2016.<http://www.ncbi.nlm.nih.gov/pmc/ articles/PMC1265913/>.
- “Parasites–Baylisascaris infection.” Centers for Disease Control and Prevention: Global Health–Division of Parasitic Diseases and Malaria. Revised 11 October 2012. Accessed 3 March 2016. <http://www.cdc.gov/parasites/ baylisascaris/geninfo/index.html>.
- Foster and Smith. “Baylisascaris procyonis (Raccoon Roundworm).” Veterinary and Aquatic Services Department Peteducation.com. Accessed 2 March 2016. <http://www.peteducation.com/ article.cfm?c=2+1621&aid=721>.
© 2018 Layne Holmes