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What is Trichinosis
Trichinosis is a disease caused by a roundworm that is found in animals that eat meat. Humans can be infected when they eat undercooked pig, horse, bear, fox, and walrus meat. The roundworm begins its life cycle in the intestines and then lodges itself in the muscles, causing pain and discomfort.
The Centers for Disease Control and Prevention estimate that 10,000 cases of trichinosis are diagnosed every year worldwide (CDC). With strict laws for meat processing and animal feed, the United States currently has very few reported cases of trichinosis, an average of only 40 per year.
Causes of Trichinosis
Trichinosis is a disease caused by eating meat that has not been thoroughly cooked and contains cysts (larvae, or immature worms) of Trichinella spiralis. Trichinella spiralis can be found in pork, bear, walrus, fox, rat, horse, and lion meat.
Wild animals, especially carnivores (meat eaters) or omnivores (animals that eat both meat and plants), should be considered possible sources of roundworm disease. Domestic meat animals raised specifically for eating under United States Department of Agriculture (government) guidelines and inspection can be considered safe. For this reason, cases of trichinosis are rare in the United States though it is a common infection worldwide.
When a person eats meat from an infected animal, Trichinella cysts break open in the intestine and grow into adult roundworms. The roundworms produce other worms that move through the gut wall and into the bloodstream. The worms invade muscle tissues, including the heart and diaphragm (the breathing muscle under the lungs). They can also infect the lungs and brain. The cysts remain alive for years.
What are symptoms of Trichinosis?
Trichinosis is usually characterized by two phases: the initial phase (intestinal) of abdominal discomfort, diarrhea, and nausea that begins one to two days after ingestion and the second phase (muscle) of muscle aches, itching, fever, chills, and joint pains that begins about two to eight weeks after ingestion. In addition, there can be “splinter” hemorrhages under fingernails and eye inflammation (conjunctivitis).
Risk factors of Trichinosis
- Improper food preparation. Trichinosis infects humans when they eat undercooked infected meat, such as pork, bear or walrus, or other meat contaminated by grinders or other equipment.
- Rural areas. Trichinosis is more common in rural areas. In the United States, higher rates of infection are found in hog-raising regions.
- Consumption of wild or noncommercial meats. Public health measures have greatly decreased the incidence of trichinosis in commercial meats, but noncommercial, farm-raised animals have higher rates of infection particularly those with access to wild-animal carcasses. Wild animals, such as bears and walruses, are still a common source of infection.
How is Trichinosis treated?
Most trichinosis infections have minor symptoms and do not require any treatment as all symptoms resolve without treatment. In those with more intense symptoms, thiabendazole (Mintezol) can be used to eliminate the adult worms in the gastrointestinal tract. Albendazole (Albenza) is another drug that may be used in some cases. The invasive and encysted larva forms of Trichinella species are treated by mebendazole (Vermox). Inflammation of infected tissues is usually treated with prednisone and is frequently used in combination with mebendazole.