Features and Occasionals

Raccoon Poop is Very Bad

By Diane Olson

Raccoons are cute. So cute. Those leathery little hands. The bandit mask and poofy striped tail. So. Darn. Cute. They’re crazy-smart, too, particularly city-dwelling raccoons. Like smarter than cats and dogs; maybe even smarter than rhesus monkeys.

They can get just about anywhere they want to get and open just about anything they want to open, and they pass their knowledge to their kits.

They also have impressive longterm memories and a vocabulary of 50-plus weird and wonderful sounds that range from chirps to whoops to gargles to trills.

Yup, raccoons are cute, smart and fascinating. They’re fun to watch, freaky to hear and damn near impossible to keep out of gardens, garages, garbage cans, fish ponds and even homes.

And their poop can kill you.

Wait, what?

OK, not their poop exactly, but what commonly lives in it.

That would be Baylisascaris procyonis (B. procyonis), also known as raccoon roundworm, a parasite than can invade the eyes (ocular larva migrans), organs (visceral larva migrans) or the brain and spinal cord (neural larva migrans). Kids and dogs are particularly susceptible to it, as they’re the ones most commonly grubbing around in the dirt.

I know what you’re thinking right about now: If this is actually a thing, then why don’t I know about it? And it’s a darn fine question. You should know about it. And you probably would if the state still provided assistance or information or much of anything, except a moldy old PDF on the Health Department’s website. But we’ll talk more about that later.

Anyway, B. procyonis is a nasty, dangerous, nematode that can do horrible, deadly things to people and animals. And what’s super creepy about it is that nobody knows how just many people or pets it actually affects.

Where does it come from?

Though it apparently does them little or no damage, raccoons are B. procyonis’ definitive host. The worm is both acquired and spread primarily in feces, though they can also become infected by eating one of the parasite’s many intermediate hosts, which include rodents, birds, rabbits and squirrels.

  1. procyonis hatches and develops to maturity inside the raccoon’s intestine, where it produces up to 250,000 eggs per day. The eggs—which are seriously sticky, resistant to everything but fire and remain viable for up to six years—are shed in the animal’s feces. After two to four weeks, they embryonate and become infectious.

That’s where people come in.

How do you get it? And what does it do?

Humans—most often children—accidentally ingest B. procyonis eggs when working or playing in the dirt, though the icky, sticky eggs can adhere to anything, including rocks, leaves, bark, lawn furniture and even toys. All it takes is an unguarded moment of eating or drinking with dirty hands or gloves. Toddlers, who tend to explore the world via their mouth, are most at risk.

Once the eggs are swallowed, they hatch in the intestine. The worms then break through the intestine wall and migrate upwards to the brain. As they travel, they can fatally scar and inflame the liver, heart, lungs and eyes.

If you’re wondering how, consider this: Adult worms are 5-8 inches long and 1/2 inch wide. We’re talking earthworm-size parasites, not microscopic ones. And they’re eating, excreting, and dying in there.

Once the worms reach the brain…well, it ain’t pretty. The severity of the damage depends on the number of worms. One autopsy found 3,200 of them. Children, with their proportionally smaller brains are more likely to suffer permanent or fatal damage. A 2005 study puts it bluntly: “To date, all survivors have been left in a persistent vegetative state or with severe residual deficits.”

Still another highly unpleasant fact about B. procyonis infection has recently come to light: Dogs, as well as raccoons, can act as primary host. So if your dog rummages around in a raccoon latrine, or chews on an infected mouse or bird or squirrel, not only can it become infected, it can also spread the parasite through its feces.

And unlike raccoons, dogs with B. procyonis aren’t asymptomatic. Like infected humans, they can suffer organ damage, go blind and die from it.

I’m sorry, I know this is disgusting and disturbing. I’m nauseous writing it. But it’s important to know, so bear with me. The super-gross part is over.

How common is this disgusting parasite?

Raccoons with B. procyonis are found throughout the U.S. and Canada, with infection rates ranging from 68% to 100%, depending on the area.

And while I can’t find any population estimates for the Salt Lake Valley, it’s a safe bet that pretty much every neighborhood, park and green space hosts at least one family. So let’s assume there are infected raccoons pooping somewhere within your daily orbit.

The good news is, human infection with B. procyonis is rare. At least documented cases are.

As of 2012, fewer than 25 cases had been verified in the United States, with about a third of the cases being fatal. Findings indicate, though, that most cases are misdiagnosed or undiagnosed, since it’s not really on anyone’s radar. And when an adult dies of liver disease, a heart attack or lung damage, or a young child dies of encephalitis or meningitis, an autopsy isn’t always performed. Especially of the brain.

Researchers are also discovering that subclinical, or asymptomatic, infection could be fairly common. A study in Chicago found that 8% of the kids tested had antibodies to the parasite, though none had shown symptoms. Other studies have found antibodies in a sizable population of adults, meaning they probably had at least a few larva lurking somewhere in the body.

A 2006 clinical microbiology study puts it this way: “Although documented cases of human baylisascariasis remain relatively uncommon, widespread contamination of the domestic environment by infected raccoons suggests that the risk of exposure and human infection is probably substantial.”

How is B. procyonis diagnosed?

There’s no commercially available test for B. procyonis infection. Which means that unless the patient mentions that they or their dog might have come into contact with raccoon feces, the odds of a diagnosis of a diagnosis of B. procyonis are just about nil.

The only other way to diagnose it is by ruling out other infections that cause similar symptoms, and then do blood and cerebrospinal fluid (CSF) tests and check the eyes for larva or lesions.

Early symptoms—which typically develop two to four weeks after infection—can range from fever, nausea and lethargy, to seizures, confusion and loss of coordination.

As the worms migrate, the symptoms change. In the liver, they cause inflammation and swelling; in the lung and heart, coughing and chest pain. Once they reach the head, light sensitivity, blindness, encephalitis and meningitis can occur.

What’s the treatment?

Yeah, this part sucks, too.

In humans, anti-parasitic drugs and corticosteroids may help in the early stages of infection, particularly if the person is asymptomatic. But once the worms start migrating upward, not much can be done. Except in the eyes, where laser treatment and corticosteroids have been successful.

In dogs, treatment is the same, though often more successful. Corticosteroids and successive doses of heartworm medication have proved to be effective against worms outside the brain. In the brain—well, not so much.

The lesson here is, if you’ve been exposed to aged raccoon poop and feel weird, get checked. Fast.

So, where do raccoons poop?

Fortunately, raccoons are gregarious and tidy poopers; rather than going just anywhere, they typically defecate in communal sites, called raccoon latrines.

Raccoons, like people, prefer to poop on flat surfaces, so latrines are often located around woodpiles and the bases of trees, or on flat rocks or stumps. Unfortunately, they also like to go in attics, sheds, sandboxes and rain gutters, and on roofs, porches, chimneys and decks.

The propensity toward communal pooping is both good and bad. While the feces are generally contained in one area (though I did once find a single, random turd on my deck), that area is highly contaminated.

So check for multiple poops in flat areas around your house and yard. The feces are long and cylindrical, similar to dogs’, but drier and with bits of berries and seeds. They’re also much stinkier than dog and cat poop.

OK, so what do you do if you do find raccoon ’doo?

Raccoon poop should be treated like hazardous waste. And, as such, it has to be disposed of very carefully and specifically.

The trouble is, the eggs are damn near impossible to kill. They stay viable forever, and there’s nothing you can spray on them. They’re resistant to acids and bases, oxidants and reductants, and protein-disrupting agents. You pretty much have to set them on fire to kill them.

So what do you do?

If you find a raccoon latrine in your yard or roof, you can hire a reputable wildlife control company to clean it up. And, ideally, remove the raccoons. (However, if you have an appealing setup, it may not be long before another family moves in.)

If you decide to do the cleanup yourself, see the Centers for Disease Control and Prevention instructions: www.cdc.gov/parasites/ baylisascaris/resources/raccoonLatrines.pdf for how to do it safely.

Also, remember that the eggs in fresh scat aren’t yet infective, so patrol often and regularly, and dispose of both dog and raccoon poop immediately.

I thought they were my friends, but no…

So yeah, sorry, this is a pretty grim article. Without even mentioning the other things that our masked friends can carry, like rabies and giardiasis, leptospirosis, salmonella and lice.

And trust me, I too find this all profoundly disturbing, as I have a very close acquaintance with a local raccoon family. They’ve been in my house, opened my cupboards and enjoyed the comfort of my sofa. All uninvited, of course.

At first I thought it was awesome and exciting. I mean, they are incredibly cool animals, aside from their disgusting parasites. Sadly, the more I learn about them, the less thrilled I am to host them. And the more I’m doing to discourage them from sticking around.

You should do the same.

B. procyonis symptoms in dogs

  • Abnormal increase in muscle tension
  • Difficulty swallowing
  • Vomiting and loss of appetite
  • Lethargy
  • Circling or rolling
  • Holding the head to one side, with muscle spasms
  • Loss of balance and coordination
  • Excessive need to lie down
  • Tremors
  • Fatigue
  • Blindness
  • Rigidity

Don’t Attract them

  • Don’t feed your pets outside, and be sure to close cat and dog doors at night. I also put an open bottle of bleach in front of my cat door when I know the raccoons are active in my yard.
  • Keep BBQ grills clean and store trash in raccoon-proof cans.
  • Make sure compost piles are tidy and hot.
  • Close off chimneys, exhaust pipes and attics with ¼-inch mesh hardware cloth, boards or metal flashing, making sure that all connections are flush and secure.
  • Trim trees back from the roof
  • Don’t grow grape or other fruit-bearing vines against or near the house.
  • Connect lights or sprinklers to a motion detector. Though raccoons can become pretty blasé about lights.

If you have them

Standard precautions should be used when cleaning up. It is nothing to get freaked out about, but:

  • Use gloves.
  • Practice good hand washing.
  • Double bag it before putting it in the trash.
  • If it is really dried out, don’t inhale particles.
  • Get rid of the problem raccoons.


Diane Olson is the author of A Nature Lover’s Almanac and a longtime CATALYST contributor. She loves writing about the natural world, in all its wondrous weirdness.

This article was originally published on May 1, 2017.