Disease
Sample of bear muscle tissue, digested. Image photographed at 100x magnification. (CDC)
The first symptoms of trichinellosis are gastrointestinal, usually occurring 1-2 days after a person consumes raw or undercooked meat from a Trichinella-infected animal. These symptoms include:

• Nausea
• Diarrhea
• Vomiting
• Abdominal pain

The classic trichinellosis symptoms often occur within 2 weeks after eating contaminated meat, and can last up to 8 weeks:

• Muscle pain
• Fever
• Swelling of the face, particularly the eyes
• Weakness or fatigue
• Headache
• Chills
• Itchy skin or rash
• Cough
• Diarrhea
• Constipation

Symptoms may range from very mild to severe and relate to the number of infectious worms consumed in the meat. Many mild cases of trichinellosis are never specifically diagnosed because they are assumed to be the flu or other common illnesses. Furthermore, many people with Trichinella infection do not experience any symptoms at all.
If the infection is heavy, persons may have trouble coordinating movements, and have heart and breathing problems. Although rare, death can occur in severe cases. For mild to moderate infections, most symptoms go away within a few months.
Diagnosis
Bear muscle showing the encysted larvae at 200x magnification. (CDC).
A diagnosis of trichinellosis is made in patients whose signs and symptoms are compatible with trichinellosis, have a positive laboratory test for Trichinella, and who can recall eating raw or undercooked pork or wild game meat.
Laboratory diagnosis of Trichinella infection is most often made by a Trichinella antibody test. In some cases a muscle biopsy may be performed.
Treatment
Safe and effective prescription drugs are available to treat both Trichinella infection and the symptoms that occur as a result of infection. Treatment should begin as soon as possible; a doctor will make the decision to treat based upon symptoms, exposure to raw or undercooked meat, and laboratory test results.

Prevention & Control

• The best way to prevent trichinellosis is to cook meat to safe temperatures. A food thermometer should be used to measure the internal temperature of cooked meat. Do not sample meat until it is cooked. USDA recommends the following for meat preparation.
• For Whole Cuts of Meat (excluding poultry and wild game)
• Cook to at least 145° F (63° C) as measured with a food thermometer placed in the thickest part of the meat, then allow the meat to rest* for three minutes before carving or consuming.
• For Ground Meat (including wild game, excluding poultry)
• Cook to at least 160° F (71° C); ground meats do not require a rest* time.
• For All Wild Game (whole cuts and ground)
• Cook to at least 160° F (71° C).
• For All Poultry (whole cuts and ground)
• Cook to at least 165° F (74° C), and for whole poultry allow the meat to rest* for three minutes before carving or consuming.

*According to USDA, "A 'rest time' is the amount of time the product remains at the final temperature, after it has been removed from a grill, oven, or other heat source. During the three minutes after meat is removed from the heat source, its temperature remains constant or continues to rise, which destroys pathogens."

• Curing (salting), drying, smoking, or microwaving meat alone does not consistently kill infective worms; homemade jerky and sausage were the cause of many cases of trichinellosis reported to CDC in recent years.
• Freeze pork less than 6 inches thick for 20 days at 5°F (-15°C) to kill any worms.
• Freezing wild game meats, unlike freezing pork products, may not effectively kill all worms because some worm species that infect wild game animals are freeze-resistant.
• Clean meat grinders thoroughly after each use.

To help prevent Trichinella infection in animal populations, do not allow pigs or wild animals to eat uncooked meat, scraps, or carcasses of any animals, including rats, which may be infected with Trichinella.