You probably saw a raccoon waddling across your deck last night. Maybe you didn't even think twice about it. They’re cute, in a "trash panda" sort of way, right? But there’s a biological reality hitching a ride in their gut that is—honestly—kind of terrifying if you stop to look at the data. We’re talking about Baylisascaris procyonis. Most people just call it raccoon roundworm.
Here is the thing: the chances of getting raccoon roundworm are statistically low, but the stakes are incredibly high. If you do get it, it isn't like a typical stomach bug or a mild case of food poisoning. It can be catastrophic.
The parasite lives in the intestines of raccoons. They don't really mind it. For them, it’s just part of being a raccoon. They poop out millions of microscopic eggs every single day. These eggs are hardy. They can survive for years in the dirt through freezing winters and scorching summers. When a human—usually a toddler playing in the dirt or a gardener who forgot to wash their hands—accidentally ingests those eggs, the trouble starts.
Why the Risk is Growing (and Where It’s Hiding)
Raccoons love us. Not because we're friendly, but because we are messy. Our suburban sprawl provides a buffet of pet food, overflowing trash cans, and cozy attic spaces. As raccoon populations density increases in urban centers, the concentration of Baylisascaris eggs in our soil goes up.
Researchers have found that in some parts of the United States, especially the Midwest, Northeast, and West Coast, nearly 70% to 90% of adult raccoons carry the parasite. That is a massive biological footprint.
The most dangerous spot is something called a "latrine." Raccoons are creatures of habit. They pick a spot—a flat rock, a fallen log, or your roof—and they use it as a communal bathroom for generations. These areas become hot zones. Thousands of eggs per gram of feces. If you have a latrine on your property, your chances of getting raccoon roundworm climb from "astronomical" to "concerningly possible" if you aren't careful during cleanup.
The Path of the Larvae
When you swallow an egg, it hatches in your small intestine. But here is where it gets weird and dark. The larvae don’t just stay in the gut like human pinworms. They are confused. They realize they aren't in a raccoon, and they panic. They start "larval migrans." They burrow through the intestinal wall and hit the bloodstream.
They can go anywhere. The liver. The lungs. The heart. But they have a terrifying affinity for the central nervous system. Because humans are "dead-end hosts," the larvae just keep growing and wandering, looking for a way out that doesn't exist. They can grow up to 2 millimeters in length—huge for a microscopic parasite—and as they push through brain tissue, they leave a trail of destruction and inflammation.
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Real Talk: How Many People Actually Get This?
If you search the CDC databases or look at medical journals like The American Journal of Tropical Medicine and Hygiene, you won't find thousands of cases. You'll find dozens. Since 1973, there have been fewer than 30 documented cases of severe neural larva migrans in the U.S.
That sounds like nothing. Why worry?
Because doctors think we are missing a lot of mild cases.
Dr. Kevin Kazacos, a professor emeritus at Purdue University and basically the world’s leading expert on Baylisascaris, has long suggested that "subclinical" infections are likely more common than we realize. If you only ingest one or two eggs, you might just feel a bit "off" or have a slight fever. Your immune system might wall it off. But because we don't routinely test for it, those cases go unrecorded. The chances of getting raccoon roundworm in a life-altering way are rare, but the prevalence of the eggs in our environment means the exposure is frequent.
Who Is Most at Risk?
- Young children. They put everything in their mouths. Dirt, wood chips, rocks. If a toddler finds an old, "clean" looking raccoon latrine in a sandbox, the risk is at its peak.
- People with pica. This is a condition where individuals crave non-food items like soil.
- Wildlife rehabbers. Handling sick raccoons without strict PPE is a gamble.
- Hobbyist gardeners. Digging in soil where raccoons travel without wearing gloves is a subtle but real pathway.
Symptoms That Mask the Truth
The reason this parasite is a nightmare for doctors is that it looks like everything else at first. It starts with nausea and tiredness. Then maybe a loss of coordination. By the time someone shows "classic" signs—like a head tilt, vision loss, or extreme lethargy—the larvae are already in the brain or the eyes (ocular larva migrans).
I spoke with a veterinarian once who mentioned that many people assume their dog just has a "weird eye thing" when it could actually be a cross-species transmission. Yes, your dogs can get this too. They can even act as intermediate hosts, shedding eggs in your house if they eat an infected rodent.
The "Hardy Egg" Problem
You can’t just spray bleach on raccoon poop and call it a day. It doesn't work. Baylisascaris eggs have a sticky outer shell that resists almost all common disinfectants. Bleach just cleans the shell.
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To actually kill the eggs, you need extreme heat. We are talking a blowtorch or boiling water. This is why when professional remediation teams clean an attic after a raccoon infestation, they often have to remove all the insulation and sometimes even char the wood underneath. It sounds like overkill until you realize those eggs can stay viable in your attic for five to ten years.
What about the "Chances" in Your Area?
The geography matters. If you live in the South, particularly in states like Georgia or Florida, the chances of getting raccoon roundworm are statistically lower because the parasite is less common in those raccoon populations, though it is starting to spread. If you're in California, New York, or Illinois? The prevalence in the local raccoon population is high.
Myths vs. Reality
People think "I’d know if there was raccoon poop in my yard."
Not necessarily.
Raccoons are stealthy. They might be using the crook of a tree ten feet up, and the rain washes the eggs down the trunk into the soil where you plant your tomatoes. Or they use the roof, and the eggs wash into the gutters and onto your lawn. You don't need to see a "pile" to be at risk; you just need to be in an environment where raccoons live.
Also, don't assume a "clean" raccoon is a safe raccoon. Even a healthy-looking animal can be shedding millions of eggs. The parasite doesn't usually kill the host; that would be bad for the parasite's survival. They've evolved a perfect, gross little partnership.
Actionable Steps to Protect Your Home
You don't need to live in a bubble, but you do need to be smart. If you have raccoons in the area, you have to change how you interact with your outdoor space.
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Secure the Perimeter
Stop the buffet. If you leave cat food out on the porch, you are inviting a Baylisascaris factory to your front door. Use heavy-duty, locking trash cans. If you have a bird feeder, clean up the spilled seed every night. Raccoons are lazy; if there's no easy food, they'll move to the neighbor's house.
The Proper Cleanup Protocol
If you find a latrine, do not grab a garden hose. Spraying it with water just aerosolizes the particles or spreads the eggs further into the soil.
- Wear a N95 mask.
- Wear disposable gloves.
- Use a shovel to carefully pick up the waste and the surrounding soil/debris.
- Double-bag it and put it in the trash (not the compost!).
- Pour boiling water over the spot where the waste was. It’s the only household method that reliably kills the eggs.
Hand Hygiene is Non-Negotiable
This sounds like basic advice, but it’s the most effective. After gardening or playing outside, scrub your hands. Teach kids to keep their hands out of their mouths until they've washed up. The eggs have to be ingested to cause the disease. If you wash them down the drain, the cycle breaks.
Deworm Your Pets
Since dogs can occasionally carry the adult worms and shed eggs, make sure they are on a monthly parasite preventative that covers roundworms. Talk to your vet specifically about Baylisascaris if you live in a high-risk area like the Pacific Northwest.
Final Perspective
It’s easy to get paranoid, but perspective is key. You are much more likely to get a common bacterial infection or even a different type of parasite like Toxoplasma from a stray cat. However, because the chances of getting raccoon roundworm come with such a high price—potential permanent neurological damage—it’s one of those rare risks where "an ounce of prevention" isn't just a cliché. It’s a survival strategy.
If you suspect you or a child has ingested raccoon feces, don't wait for symptoms. Go to the ER. Mention Baylisascaris specifically. There is a drug called Albendazole that can sometimes stop the larvae before they reach the brain, but it’s a race against time.
Keep the trash cans locked, keep the kids’ sandbox covered, and keep the boiling water handy for those "surprises" on the deck. Being aware of the risk is usually enough to make the actual danger almost zero.