You probably think parasites are a "somewhere else" problem. We’ve been conditioned to believe that unless you’re trekking through a remote rainforest or drinking from a stagnant pond in a developing nation, your gut is a fortress. That’s a mistake. The truth about how can you get parasites in your body is actually much more mundane, closer to home, and honestly, a little bit gross.
It happens at the local organic bistro. It happens when you kiss your puppy. It happens because you touched a grocery cart handle and then accidentally bit a hangnail.
Parasites are biological opportunists. They don't care about your zip code. According to the Centers for Disease Control and Prevention (CDC), millions of Americans carry parasitic infections, many without even realizing it. We aren't just talking about giant tapeworms either; we're talking about microscopic protozoa that can live in your bloodstream or tissue for decades.
The Sushi and Steak Tartare Dilemma
Raw or undercooked meat is the classic gateway. If you’re a fan of medium-rare steak or "wild-caught" salmon sashimi, you're playing a statistical game.
Take Diphyllobothrium latum, better known as the fish tapeworm. It’s one of the largest parasites that can inhabit humans, sometimes reaching lengths of 30 feet. You get it by eating raw or undercooked freshwater fish—or marine fish that spend time in river systems, like salmon. The larvae encyst in the muscle of the fish. When you eat that "perfectly seared" fillet that’s still cold in the middle, those larvae wake up in your digestive tract.
It’s not just fish. Toxoplasma gondii is a protozoan parasite that the CDC estimates infects over 40 million people in the U.S. alone. While often associated with cat litter, a massive percentage of infections come from eating undercooked pork, lamb, or venison. It’s stealthy. Most people have zero symptoms because a healthy immune system keeps it in check. But the parasite stays there, dormant in your tissues, for the rest of your life.
Contaminated Water: The Invisible Threat
Water is the most common vector for parasites globally. But don't think your municipal water treatment plant is a 100% guarantee of safety.
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Cryptosporidium and Giardia are the two big names here. They are notoriously hardy. These parasites have a protective outer shell (a cyst) that makes them resistant to chlorine disinfection. If a local water supply suffers a "break" or if heavy rainfall causes agricultural runoff to overwhelm a system, these cysts can end up in your tap.
In 1993, Milwaukee had a massive Cryptosporidium outbreak. Over 400,000 people got sick. It was the largest waterborne disease outbreak in U.S. history. Even today, public swimming pools and "splash pads" are frequent sites of transmission. Someone has an accident in the pool, the chlorine doesn't kill the Crypto fast enough, and you swallow a single mouthful of water. That’s all it takes.
Your Backyard Is a Biohazard
We love our pets, but they are essentially mobile parasite taxis.
Hookworms and roundworms are incredibly common in dogs and cats. The eggs are passed in their feces. If you’re gardening in your backyard without gloves, or if you’re walking barefoot across a lawn where a neighbor’s dog "did its business" a week ago, you’re at risk.
Hookworm larvae can actually penetrate human skin directly. This is called cutaneous larva migrans. You don't even have to swallow them; they just burrow through the bottom of your foot. It causes an itchy, red, serpentine track under the skin.
Then there’s the "fecal-oral route." It’s a polite medical term for a disgusting reality. You pet your cat, she has microscopic eggs on her fur from grooming herself, you later eat a sandwich without scrubbing your hands with surgical precision, and suddenly you’re hosting a colony of Toxocara.
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The Produce Problem
"Wash your vegetables" isn't just something your mom said to annoy you. It's vital.
When you wonder how can you get parasites in your body, you have to look at the soil. Much of our produce is grown in fields that use "night soil" (human waste) or animal manure as fertilizer. If that manure isn't properly composted at high temperatures, the parasite eggs survive.
Cyclospora cayetanensis is a parasite often linked to imported fresh produce like raspberries, basil, and cilantro. You can’t just "shake it off." These parasites are sticky. They cling to the nooks and crannies of a lettuce leaf. If the farm workers don't have access to proper sanitation or if the irrigation water is contaminated with sewage, your "healthy" kale salad becomes a delivery system for intestinal distress.
Why Your Doctor Might Miss It
The medical community in the West often treats parasites as a "traveler’s disease." If you haven't been to a tropical climate recently, many doctors won't even put a stool test on the table.
This is a massive oversight. Parasites like Strongyloides stercoralis can live inside a human host for 30 or 40 years through a process called autoinfection. They keep reproducing inside you without ever needing to exit and re-enter. You could have picked it up as a child playing in the dirt and not show significant symptoms until your immune system weakens in your 60s.
Diagnosis is also notoriously difficult. Many parasites are "intermittent shedders." This means if you provide a single stool sample to a lab, and the parasite didn't happen to release eggs on that specific day, your test comes back negative. You get a "clean bill of health" while actually hosting a thriving ecosystem of uninvited guests.
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Subtle Signs You Might Be Hosting
It’s rarely like the movies. You won’t usually see something crawling. Instead, it’s a slow burn of vague symptoms.
- Chronic Digestive Issues: Bloating, gas, or diarrhea that comes and goes without a clear trigger.
- Unexplained Fatigue: Parasites eat your nutrients. You’re eating for two, but the "other" is a microscopic thief stealing your B12 and iron.
- Skin Irritations: Rashes, hives, or itchy skin (especially at night) can be a systemic reaction to parasite waste products.
- Teeth Grinding: Bruxism, especially during sleep, has been anecdotally and sometimes clinically linked to the stress parasites put on the nervous system.
- Anemia: If you’re low on iron despite eating red meat, something might be bleeding you internally—specifically hookworms.
Real-World Defense Strategies
You don't need to live in a bubble. You just need to change how you interact with the "dirty" world.
First, the kitchen. Stop using the same cutting board for vegetables and meat without a high-heat dishwasher cycle in between. If you’re eating wild game or freshwater fish, freeze it at -4°F (-20°C) for at least seven days. This kills most larvae. Your home freezer might not get that cold, so check the settings.
Second, hand hygiene. Hand sanitizer does basically nothing against Giardia or Cryptosporidium. You need the mechanical action of soap and running water to physically slide the cysts off your skin. Scrub for 20 seconds. Every time. Especially after the gym, the grocery store, or the park.
Third, be skeptical of water. If you’re hiking, use a filter rated for "cysts" or boil your water. If you’re in an area with questionable plumbing, skip the ice cubes in your soda. Ice machines are notorious breeding grounds for biofilm and parasites because they are rarely cleaned properly.
Actionable Steps for Better Health
If you suspect you've been exposed, don't just go buy a "para-cleanse" kit from a health food store. Most of those are just glorified laxatives.
- Request a "Triple Stool Sample": Ask your doctor for an Ova and Parasite (O&P) test that covers three different days. This increases the chance of catching a shedder.
- Blood Work: Check your Eosinophil levels. Eosinophils are a type of white blood cell that often spikes specifically in response to parasitic infections or allergies.
- Pet Protocols: Deworm your pets regularly, even if they don't "look sick." Wear gloves when cleaning litter boxes or gardening.
- Cooking Temps: Use a meat thermometer. Reach 145°F for whole meats and 160°F for ground meats.
- Wash Produce with Friction: Don't just soak your greens. Use your hands to rub the surface of fruits and vegetables under running water to dislodge cysts.
Understanding how can you get parasites in your body isn't about fear; it's about awareness. Our world is shared with millions of organisms. Most are harmless, but a few are looking for a free ride. A little bit of heat in the kitchen and a lot of soap in the bathroom go a long way in making sure you aren't their next destination.