That’s the bone-chilling shriek of America’s favorite pest, the trash panda. Or Raccoon. And while they may sound like demons shredding the flesh from helpless babes, there’s something even more terrifying about them: Their poop.

Raccoon poop harbors the ovum of the horrifying parasitic worm Baylisascaris procyonis. It’s a roundworm nematode that spends most of its life in raccoon intestines. The worms live and reproduce deep inside the nether regions of the trash panda. Adult females can lay hundreds of thousands of eggs a day, which end up in raccoon poop. If another raccoon swallows those eggs, the worm hatches in its intestines and goes about its slimy business. But if another animal swallows the eggs, they get nasty. Really nasty.

If a mouse gets a gut full of baylisascaris eggs, they hatch and burrow out of the intestines and into organs, muscles, whatever. When they’ve found a nice home in a lung or liver or brain, they encyst and wait for the mouse to be eaten by a raccoon. When they’re snuggled back in a raccoon’s bowels, they go about life as usual.

The worms will do the same thing in dozens of different animals. Including humans.

The first case of baylisascaris in humans was reported in 1984. A 10-month-old baby in rural Pennsylvania was infected after a family of raccoons nested un an unused chimney. The infection was fatal—the worms infested the boy’s brain and heart.

Fewer than 25 cases of raccoon worm infestation have been reported in the US since then, which is an infinitesimal number, but every single case reads like a Lovecraftian fever dream. If you’re squeamish and you haven’t already turned me off, you may want to skip ahead a few minutes. These are actual cases documented at CDC:

Oklahoma: May 2013 – A 31-year-old woman was infected from her pet raccoon. She went to the doctor for headaches and generalized pain. She was treated with anti parasitic drugs and corticosteroids for three weeks and got better. But 16 months later she got sick again and despite further treatments, experienced swelling in her brain that left her with headaches, numbness, and an awkward gait.

Minnesota: December 2015 – A 7-year-old boy was evaluated at an ophthalmology clinic for worsening vision in his right eye. Examination revealed a larva compatible in size with Baylisascaris procyonis. He lived in an area where raccoons were common. Serum tests detected Baylisascaris procyonis antibody. The patient was treated with anti parasitic drugs and corticosteroids, and retinal photocoagulation laser therapy. He had near total recovery of his vision upon completion of therapy.

California: June 2015 – A 63-year-old male was evaluated at a local hospital for progressive memory impairment, loss of motor function, fatigue and confusion. He worked as a contractor, and his family reported that he rarely washed his hands before meals. Raccoons had been observed under his home and at his rural jobsite. Baylisascaris procyonis antibody was detected in his blood. The patient was treated with anti parasitic drugs and corticosteroids for 6 weeks; 4 months after his diagnosis, he demonstrated only partial recovery of cognitive and motor function.

There are more, many more, but I’ll stop spewing the nightmare fuel. This is terrifying, you get it. But really, how dangerous is raccoon poop?

A single adult female worm can lay between 115,000 and 877,000 eggs per day. A single raccoon can harbor multiple worms and shed as many as 45 million eggs in a day. According to the CDC, eggs can last for months and maybe even years in the environment if left undisturbed. And raccoon poop is seemingly everywhere in cities.

Zoologist and raccoon expert Sam Zeveloff said in a recent Slate article that the raccoon population has had an “astonishing” surge during the last 80 years. The Journal of Mammalogy reported in 2010 that 156,416 raccoons were caught in Toronto, Canada, between 1994 and 2007. The density in southern Ontario ranged between 3.4 and 13.6 raccoons/km2 when density in northern Ontario was about 1.5 raccoons/km2.

According to a study by German zoologist Frank-Uwe Michler in the early 2000s, there are about 50 to 150 animals per square kilometer in most urban cities in the US. Raccoons have also spread to most of Europe, where density is about the same. The little critters just can’t resist loaded trash cans, which overflow with tasty food waste. They also love to nest in old sheds, garages, abandoned houses, and attics. According to another German book “Der Waschbar,” the percentage of urban raccoons sleeping in abandoned or occupied houses varies from 15% in Washington, DC (1991) to 43% in Kassel (2003).

And those numbers are more than a decade old. There could be even more trash pandas roaming the mean streets of major metropolitan areas around the world.

Oh, and it’s estimated that between 70 and 90 percent of all raccoons have worms.

This could be a big problem. In fact, the CDC published an article warning of possible future outbreaks and, I’m not even making this up, the risk of Baylisascaris procyonis being used in bioterrorism. You heard that right, the CDC wrote on its website that trash panda worms could be weaponized. Right there on the internet, for everyone to see. This falls into the category of “for real?!” or “why would you give anyone that idea?!” “Are you insane?!”

Actually, a parasitology student intentionally poisoned his roomates with pig roundworms in 1970. According to a grizzly io9, article American student Eric Kranz studying parasitology at Macdonald College in Montreal got kicked out for not paying his rent. He allegedly threatened to poison his roomies with the parasites he was studying. A few days later, four of his roomates fell ill with Ascaris suum, or pig roundworm, infections. Two of them nearly died. Kranz was charged with attempted murder but was acquitted. The judge ruled that the prosecution hadn’t eliminated the possibility that the roommates’ food had become contaminated in some other way, like by sewage backup in the kitchen sink. I don’t know, sounds fishy to me. Or wormy, maybe.

So the CDC has a right to be concerned with weaponized raccoon scatt. Fortunately, baylisascaris eggs are relatively large and are easily filtered out in water treatment plants. Yay municipal water treatment facilities! Still, the CDC worries about the worms being used in localized attacks. Which, you know, is terrifying.

So if brain-eating worm eggs are everywhere, why aren’t we all infected? The CDC conducted a study of 347 wildlife rehabilitators in the US between 2012 and 2015. Twenty four of them, or about 7 percent, had Baylisascaris antibodies in their blood, meaning they were either infected or had been infected in the past. None of them were exhibiting any symptoms of worms eating their brains from the inside out.

Researchers concluded that Baylisascaris exposure and infection may be more common than we think, but that most of us either fight off the infection or show no signs. They postulate that serious infection may only occur in people who don’t possess the means to fight it off. But the research simply hasn’t been done. In their words:

Although baylisascariasis may indeed be underdiagnosed, asymptomatic human infection may be the typical response, and the limited number of cases reported may indicate that an unrecognized immune defect is necessary for severe infection to occur. The prevalence of asymptomatic infection in human populations has yet to be determined.

How do you treat a nightmare trash panda worm infestation? The best and only treatment is the vermicidal Albendazole. The drug was developed in 1975 and is used to treat all kinds of nasty worm infections. The drug works by poisoning worms intestinal cells. It also interrupts egg production and development. Essentially the worms can’t digest any food, run out of energy, and die. It seems to be one of those miracle drugs that works really well with minimal side effects, which can include abnormal liver function that returns to normal once you stop taking it. Some people do have severe reactions to the drug, but it’s pretty rare.

What should you do if you, like me, find some raccoon poop in your back yard? Burn down your house and collect the insurance money. No, seriously, you should very carefully clean it up. Wear some gloves and probably a good dust mask and shovel it into a plastic bag. Seal it up and throw it away.

Unfortunately, disinfectants won’t kill the worm eggs. Not even bleach. The only things that work are heat and time. If you’re really paranoid about it, I suppose you could pour boiling water on it, or hit it with a propane torch—which is actually a recommendation on the CDC website. You can also hire professionals to come in hazmat suits to clean up your property, but that may be overkill. Unless you have toddlers who love to dig in the dirt, then by all means enact a quarantine and bust out the flamethrowers.

So what does it all mean? Are we on the verge of a plague of raccoon worms? A trash panda pandemic? No! Definitely not! But remember, I am not a scientist and I can’t give you any professional advice or make any informed predictions. If you want to learn more, do some digging. But not around raccoon poop.

Oookay, so that was gross. Here are some fun raccoon facts culled from the pedia of wikis to help clear your mind of figurative (or literal, if you’ve been infected) worms.

Raccoons are the largest members of the procyonid family, which also includes coatis, kinkajous, olingos, olinguitos, ringtails and cacomistles. And while they may look like fat bandit squirrels, they’re actually more closely related to bears. They’re native to North America.

They can grow to 40 to 70 cm (16 to 28 in) and a body weight of 5 to 26 kg (11 to 57 lb).

Raccoons are omnivores. They’ll eat pretty much anything, including fruit, vegetables, rodents, birds, bugs, and, of course, trash.

The word “raccoon” was adopted into English from the native Powhatan term aroughcun or arathkone. It’s believed to be derived from the Proto-Algonquian root *ahrah-koon-em, meaning “one who rubs, scrubs and scratches with its hands.”

In many languages, the word for raccoon refers to the animal’s somewhat adorable washing behaviour. In German, they’re called waschbar. In Russian, poloskun, which translates into “rinser.”

In the 1830s, the United States Whig Party used the raccoon as an emblem, causing them to be pejoratively known as “coons” by their political opponents, who saw them as too sympathetic to African-Americans. Soon after that the term became an ethnic slur, especially in use between 1880 and 1920. Which was horrible, of course.

Raccoons have very dextrous front paws and can easily open complex locks and can remember how to open them for up to three years. By all accounts they’re some of the smartest animals out there, equalling or besting primates like the rhesus macaque.

In indigenous American mythology, the raccoon often plays the role of the trickster, outsmarting other animals like coyotes and wolves. The Dakota Sioux believe the raccoon has natural spirit powers, since its mask resembled the facial paintings, two-fingered swashes of black and white, used during rituals to connect to spirit beings. The Aztecs linked supernatural abilities especially to females, whose commitment to their young was associated with the role of wise women in their society.

Raccoons were routinely trapped for their fur. In the early 1900s, raccoon driving coats were extremely popular among people who could afford fancy automobiles. Raccoon hunting and trapping continued in scale through the 1960s. The ‘50s TV show, Davy Crockett, King of the Wild Frontier, caused a spike in demand for coonskin caps. By 1962/63, two million raccoons were killed for their pelts. Even though Crockett probably didn’t even wear a coonskin cap and the one on the TV show was fake.

Raccoons were a food source for Native Americans and settlers. Raccoon meat was extensively eaten during the early years of California, where it was sold in the San Francisco market for $1–3 apiece. The first edition of The Joy of Cooking, released in 1931, contained a recipe for preparing raccoon.

In 1926, a man from Mississippi gave President Calvin Coolidge a female raccoon that was supposed to be served at Thanksgiving dinner. The Coolidge family couldn’t bear to eat her though. They named her Rebecca and kept her as a pet. Rebecca roamed the White House and had her own tree in the lawn. The Coolidge family eventually donated her to the National Zoo in DC. There’s a picture of First Lady Grace Coolidge holding Rebecca on Wikipedia. You should go look at it, it’s friggin adorable.

And that’s it. Thanks for listening. There’s plenty more to learn about raccoons (and their poop). Just type either or both of those words into your favorite information hose and guzzle the knowledge down. I know I did.

The raccoon fighting sounds are courtesy of, a nonprofit raccoon mixed martial arts school. More info about them at No, really, it’s actually from The Critter Window on YouTube. It’s Indiana’s first live critter cam. Go check it out for videos of critters doing critter things.

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