Sample of bear muscle tissue, digested. Image photographed at 100x magnification. (CDC)

The first symptoms of trichinellosis are gastrointestinal, usually occuring 1-2 weeks after a person consumes raw or undercooked meat from a Trichinella-infected animal. These symptoms include:

• Nausea
• Diarrhea
• Vomiting
• Abdominal pain

Further symptoms (that correspond with the second phase of infection) usually occur about 2 weeks after eating contaminated meat, and can last up to 8 weeks:

• Headaches
• Fevers
• Fatigue
• Chills
• Cough
• Eye swelling
• Aching joints
• Muscle pains
• Itchy skin
• 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.