You get trichinosis by eating raw or undercooked meat that contains Trichinella parasite larvae. The larvae sit inside tiny cysts in the animal’s muscle tissue, and when you eat that meat without cooking it thoroughly, your stomach acid dissolves the cysts and releases the parasites into your digestive system. From there, they invade the lining of your small intestine, mature into adult worms, and produce new larvae that travel through your bloodstream and burrow into your own muscles.
The infection is rare in the United States, averaging about 15 cases per year, but it still happens regularly among people who eat wild game or improperly prepared pork.
Which Meats Carry the Highest Risk
Bear meat is the single biggest source of trichinosis in the U.S. today. CDC surveillance data from 2008 to 2012 found that 91% of cases linked to non-pork meat came from bear. Wild boar, walrus, seal, wolf, fox, and wildcat also carry the parasite. The common thread is that these are meat-eating or scavenging animals, which means the parasite cycles easily through their food chain.
Pork used to be the primary culprit, but commercial pork production in the U.S. has largely eliminated the risk through changes in how pigs are raised and fed. Pork still accounted for about 26% of cases during that same surveillance period, with roughly half linked to commercial products and the rest to wild boar or home-raised pigs. Deer meat was responsible for a small number of cases as well, likely from cross-contamination during processing or from deer that had scavenged infected carcasses.
What Happens Inside Your Body
The infection plays out in two distinct phases. The first phase begins within one to two days of eating contaminated meat. Your stomach breaks down the cysts, freeing the larvae, which then penetrate the wall of your small intestine and grow into adult worms. During this stage you may experience nausea, diarrhea, vomiting, and abdominal pain. These symptoms can look a lot like food poisoning, which is why many early infections go unrecognized.
The second phase starts about two to eight weeks later. The adult worms mate inside your intestine, and the females release a new generation of larvae into your bloodstream. These larvae travel throughout your body and embed themselves in skeletal muscle, the type of muscle you use to move. This is when the more distinctive symptoms appear: muscle pain, swelling around the eyes, fever, and fatigue. In severe cases, the larvae can cause inflammation in the heart or brain, which can be life-threatening. The severity depends largely on how many larvae you consumed.
Safe Cooking Temperatures
Cooking meat to the right internal temperature is the most reliable way to kill Trichinella larvae. For whole cuts of pork, the USDA recommends an internal temperature of 145°F (63°C) held for at least 3 minutes. Ground meat of any kind should reach 160°F (71°C). Game birds need to hit 165°F (74°C). Always use an instant-read meat thermometer rather than judging by color, since meat can look done while still harboring live parasites in its center.
When roasting wild game, keep your oven set to at least 325°F (163°C) to ensure even heat penetration. Let the thermometer probe reach the thickest part of the meat, away from bone, for the most accurate reading.
Why Freezing Isn’t Always Enough
Freezing pork for three days or longer generally kills the most common species, Trichinella spiralis. Some guidelines suggest freezing wild game for at least three weeks before eating it. But here’s the catch: certain Trichinella species found in Arctic and cold-climate animals are freeze-resistant. T. nativa, T6, and a more recently identified species called T. chanchalensis (found in wolverines) can survive prolonged freezing. This means that if you’re preparing bear, walrus, or other wild game from northern regions, you cannot rely on freezing alone to make the meat safe. Cooking to the proper internal temperature is the only dependable method for these meats.
Handling Wild Game Safely
Hunters processing their own kills should treat all bear and wild boar as potentially infected. Prevent meat juices from dripping onto other food, and clean every surface and utensil that touches raw meat or its juices with hot, soapy water. Keep raw meat refrigerated below 40°F (5°C) to slow bacterial growth, though cold temperatures alone won’t eliminate Trichinella. Cross-contamination during butchering is a real concern: using the same cutting board or knife for infected meat and then for other foods can transfer larvae.
Curing, smoking, and drying meat are traditional preservation methods, but they are not reliably effective at killing Trichinella larvae. Homemade jerky, sausage, or smoked meat from wild game should not be considered safe unless the meat was first cooked to a safe internal temperature.
How Trichinosis Is Diagnosed and Treated
Diagnosis can be tricky because early symptoms overlap with common stomach bugs. Doctors typically look for a combination of clues: a history of eating wild game or undercooked pork, the characteristic pattern of muscle pain plus facial swelling, and blood tests showing elevated levels of eosinophils (a type of white blood cell that spikes during parasitic infections). Antibody tests can confirm the diagnosis, though they may not turn positive until several weeks after infection.
Treatment works best when started early. Antiparasitic medications can kill the adult worms in the intestine and the migrating larvae before they fully embed in muscle. If treatment doesn’t begin within the first several days of infection, longer or repeated courses may be needed. In more severe cases where larvae have already reached the muscles and triggered significant inflammation, steroids are sometimes added to reduce swelling and prevent complications in the heart or other organs. Most people recover fully, though muscle aches can linger for weeks or even months after the infection clears.