Many everyday foods can harbor parasites, from raw fish and undercooked meat to fresh salads and berries. The risk depends on how the food is sourced, handled, and prepared. Here’s a breakdown of the foods most likely to carry parasites and what you can do to protect yourself.
Raw and Undercooked Fish
Fish is one of the most common sources of parasitic infection, especially when eaten raw or lightly cured. Two parasites dominate the risk. The first is a roundworm called Anisakis, found in raw or undercooked fish and squid. The second is the fish tapeworm, which you can pick up from raw, undercooked, or marinated freshwater fish or fish that spawn in freshwater rivers, like salmon. Cases of fish tapeworm have been linked to salmon, perch, char, and pike.
Sushi restaurants in the U.S. are required to follow FDA guidelines that significantly reduce this risk. Fish intended for raw consumption must be frozen at specific temperatures to kill parasites: either held at -4°F (-20°C) for seven days, or flash-frozen at -31°F (-35°C) until solid and then stored at that temperature for 15 hours. This is why reputable sushi restaurants use commercially frozen fish rather than serving it straight off the boat. If you’re preparing raw fish at home, your household freezer may not reach these temperatures consistently.
Pork and Wild Game
Undercooked pork has long been associated with Trichinella, a parasitic roundworm whose larvae burrow into muscle tissue and form cysts. While commercial pork production in the U.S. has made domestic pork much safer than it once was, wild game is a different story. Bear, wild boar, walrus, wildcat, fox, wolf, and seal meat all carry a real risk of Trichinella infection. Even tasting a small amount of raw or undercooked game meat during preparation is enough to cause infection.
Homemade jerky and sausage made from these meats are also potential sources. Curing, salting, drying, smoking, or microwaving meat does not consistently kill the worms. And unlike with pork products, freezing wild game may not work either, because some Trichinella species found in wild animals are freeze-resistant.
Pork also carries two other concerns. The pork tapeworm can cause an intestinal infection from eating undercooked pork, but its larval stage can migrate to other tissues in the body, a more serious condition. Toxoplasma, a single-celled parasite best known for its connection to cats, also infects pork, lamb, and venison. You can pick it up from any undercooked meat.
Beef
Beef has its own tapeworm species. Eating raw or undercooked beef, like rare steak tartare, can lead to an intestinal tapeworm that grows in your digestive tract. The beef tapeworm causes a milder infection than its pork counterpart, since its larvae don’t migrate into other body tissues. Still, hosting a tapeworm that can grow several feet long is something most people would prefer to avoid.
Fresh Fruits and Vegetables
Produce is a surprisingly common vehicle for parasites, particularly single-celled organisms that are too small to see. The biggest offender in the U.S. is Cyclospora, a parasite that contaminates fresh herbs, leafy greens, and berries. In 2025, the CDC tracked 1,180 domestically acquired cases of cyclosporiasis across 37 states, with illnesses peaking around late June and July. An additional 1,346 cases were linked to food or water consumed during international travel. People who got sick ranged from age 1 to 90, and about 9% of domestic cases required hospitalization.
Cryptosporidium, another microscopic parasite, shows up on a wide range of vegetables. Studies of market produce have found Cryptosporidium on virtually every vegetable type tested. Giardia, which causes intense diarrhea and cramping, also contaminates produce through irrigation water or handling by infected workers. Outbreaks of giardiasis, cryptosporidiosis, and cyclosporiasis have all been traced back to contaminated fresh produce.
The challenge with produce is that these parasites form tough, protective shells (called oocysts or cysts) that cling to surfaces and resist simple rinsing. A large meta-analysis of sanitization methods found that rinsing vegetables with chlorinated water alone reduced parasites, but the most effective approach combined chlorine solutions with physical scrubbing, brushing, or a preliminary soak in detergent. That combination removed parasites with roughly 99% effectiveness compared to unwashed vegetables. Plain water rinsing is better than nothing, but it’s far less effective than a thorough scrub.
Which Parasites Cause the Most Trouble
Not all food parasites affect you the same way. They fall into two broad categories. Single-celled parasites (protozoa) like Cyclospora, Cryptosporidium, Giardia, and Toxoplasma tend to cause gastrointestinal symptoms: watery diarrhea, cramping, nausea, and fatigue. Most healthy adults recover, though symptoms can last weeks and be quite miserable. Toxoplasma is a special case because it rarely causes symptoms in healthy people but poses serious risks during pregnancy and for anyone with a weakened immune system.
Worm parasites (helminths) work differently. Tapeworms from beef or pork can live in your intestines for years, sometimes with minimal symptoms beyond occasional digestive discomfort. Trichinella is more acute: within one to two weeks of eating contaminated meat, you may develop fever, muscle pain, swelling around the eyes, and fatigue as the larvae migrate through your body. The pork tapeworm’s larval stage can form cysts in the brain and other organs, which is the most dangerous foodborne parasitic infection you’re likely to encounter.
How to Reduce Your Risk
Cooking meat to the right internal temperature is the single most reliable way to kill parasites. For whole cuts of beef, pork, or lamb, that means reaching at least 145°F (63°C) at the thickest part, then letting the meat rest for three minutes. The temperature continues rising during that rest period, finishing off remaining pathogens. Ground meat needs to hit 160°F (71°C) with no rest time necessary. Use an actual meat thermometer rather than guessing by color or texture.
For produce, wash everything thoroughly under running water and scrub firm-skinned fruits and vegetables with a brush. Leafy greens and herbs deserve extra attention since their irregular surfaces trap parasites. Peeling fruits and vegetables removes surface contamination entirely, which is especially useful when traveling in regions with less reliable water sanitation.
For fish you plan to eat raw, buy from reputable sources that follow commercial freezing protocols. Avoid preparing homemade sushi or ceviche with fresh-caught fish that hasn’t been properly frozen first. Cooking fish to 145°F eliminates any concern entirely.
Wild game requires the most caution. Cook it thoroughly to at least 160°F throughout, and don’t rely on freezing, smoking, or curing to make it safe. Resist the urge to taste the meat before it’s fully cooked, since even a small bite of raw game can deliver enough Trichinella larvae to cause infection.