Yes, parasites can be found in meat. Several species of worms and single-celled organisms naturally infect the muscle tissue of animals raised for food, and they can cause illness in humans who eat that meat raw or undercooked. The practical risk varies widely depending on the type of meat, where it came from, and how it’s prepared.
Which Parasites Are Found in Which Meats
Different parasites tend to show up in different animals. The main ones worth knowing about are tapeworms, roundworms, and a single-celled parasite called Toxoplasma.
Pork has historically been the meat most associated with parasites. The pork tapeworm can form cysts in the muscle tissue of pigs, and a roundworm called Trichinella spiralis burrows into muscle and encases itself in tiny sacs. That said, commercial pork in the United States is now remarkably safe. A USDA survey tested over 3.2 million pigs raised under the national quality assurance program and found zero animals infected with Trichinella, putting the estimated prevalence at less than 1 in a million. This is the result of decades of changes in how commercial hogs are raised and fed.
Beef can carry the beef tapeworm, which people contract by eating raw or undercooked infected meat. Beef is less commonly associated with Toxoplasma than lamb or pork.
Lamb carries the highest risk for Toxoplasma gondii, a microscopic parasite found worldwide. Infections are more frequent in lamb and pork than in beef or chicken, with lamb representing the greatest risk to humans. Toxoplasma is the third leading cause of death from foodborne illness in the U.S., and food transmission accounts for an estimated 40 to 60 percent of all human Toxoplasma infections.
Wild game is where the real concern lies today. Bear, wild boar, walrus, cougar, and fox can all carry Trichinella. Most current U.S. cases of trichinosis come from eating raw or undercooked wild game rather than commercial pork. Even tasting a small amount of raw wild game during preparation is enough to cause infection.
Fish harbor their own parasites. Anisakis larvae are commonly found in the muscle tissue of fish like mackerel and can cause a painful stomach infection if swallowed alive. This is why sushi-grade fish is frozen before serving.
How Meat Parasites Infect the Human Body
The infection process is surprisingly straightforward. When you eat meat containing parasite larvae or cysts, your stomach acid breaks down the surrounding tissue and releases them. The larvae then enter the wall of your small intestine, where they grow into adult worms and reproduce. In the case of Trichinella, new larvae travel through the bloodstream and bury themselves in your muscle tissue, forming new cysts. This cycle is what produces the more serious symptoms.
Tapeworms work differently. They attach to the intestinal wall and can grow to considerable lengths, absorbing nutrients from the food you eat. The pork tapeworm poses an additional risk: its larval stage can migrate out of the intestine and form cysts in other tissues, including the brain, a condition called cysticercosis.
Toxoplasma, being a single-celled organism, invades cells throughout the body. It can only complete its full reproductive cycle in cats, but it forms dormant cysts in the muscle tissue of virtually any warm-blooded animal, which is how it ends up on your plate.
Symptoms and Timeline
Many parasitic infections from meat are mild enough that people mistake them for a stomach bug. Some cause no noticeable symptoms at all. When symptoms do appear, they tend to follow a predictable pattern, at least for Trichinella, the best-studied meat parasite.
Within one to two days of eating contaminated meat, you may notice nausea, vomiting, diarrhea, and stomach pain as the larvae establish themselves in the intestine. One to two weeks later, a second wave of symptoms hits as new larvae migrate through the body: fever, chills, facial swelling (especially around the eyes), headache, muscle and joint aches, fatigue, rash, and cough. In mild to moderate cases, most symptoms fade within a few months without treatment. Heavy infections can cause difficulty with coordination, and in rare cases, heart and breathing problems that can be fatal.
How sick you get generally depends on how many larvae you consumed. A few bites of undercooked wild boar might cause mild flu-like symptoms. A larger serving of heavily infected meat can produce a serious illness.
Cooking Temperatures That Kill Parasites
Heat is the most reliable way to destroy parasites in meat. The USDA’s safe internal temperatures are designed to eliminate both bacteria and parasites:
- Beef, pork, lamb, goat, and bison steaks, roasts, and chops: 145°F (63°C) with a 3-minute rest
- Ground beef, pork, lamb, or sausage: 160°F (71°C)
- Wild game (venison, rabbit, boar, bear): 160°F (71°C)
Use a meat thermometer and measure at the thickest part. Color alone is unreliable. A pork chop can look done while the center is still below the safe threshold.
Wild game deserves extra caution. Because Trichinella is still actively circulating in wild animal populations, the higher minimum of 160°F applies to all wild game, with no option for a pink center.
Freezing Fish to Prevent Anisakis
For fish that will be eaten raw, freezing is the primary safety measure. Research on mackerel, one of the most commonly parasitized fish, found that all Anisakis larvae died when the core temperature of the fish reached negative 35°C through rapid freezing, or when the fish was held at negative 20°C for at least 24 hours after the core reached that temperature. Simply putting fish in a home freezer for a few hours is not sufficient, since it takes time for the center of the fish to reach the target temperature.
Restaurants serving sushi and sashimi in the U.S. are generally required to use fish that has been commercially frozen to these specifications. If you’re preparing raw fish at home, buying commercially frozen sushi-grade fish is the safest approach.
Who Faces the Highest Risk
Hunters and people who eat wild game are the group most likely to encounter parasites in their meat today. The shift away from commercial pork as a source of trichinosis has been dramatic, but wild boar and bear remain significant carriers.
People who prefer rare or medium-rare meat face more exposure than those who cook to well-done. This applies most to lamb and pork, where Toxoplasma cysts are more common. For beef steaks, the interior of a solid cut is generally sterile since parasites and bacteria live on the surface or in cysts, and searing addresses surface contamination. Ground meat is different: the grinding process mixes surface material throughout, which is why ground meat has a higher minimum temperature.
Toxoplasma is especially concerning for pregnant women and people with weakened immune systems. In healthy adults, the parasite often causes no symptoms or a mild flu-like illness. But it can cause serious complications during pregnancy and severe illness in immunocompromised individuals. The CDC estimates Toxoplasma causes roughly 848 hospitalizations and 44 deaths per year in the U.S. from foodborne transmission alone.