Trichinosis is caused by parasites from the genus Trichinella. There are a number of species in this genus, but the one with the most historical association with human illness is T. spiralis. T. spiralis is widely disseminated and has been reported in up to 150 species. Human infections have been traditionally related to consumption of undercooked pork products containing the cyst of infective larva. The parasite larva matures in the small intestinal tract, releasing larva that penetrate the intestinal wall and migrate to muscle tissue where they encyst. Symptoms of trichinosis in humans are nausea, vomiting, fatigue, fever, and abdominal discomfort. Symptoms and signs of muscle infection include headaches, fevers, chills, cough, eye swelling, aching joints, muscle pain, and itchy skin. Mebendazol and thiabendazole can be used to treat the infection in the early stages; however once the parasite has invaded the muscles, treatment is limited to supportive care. Modern swine farming practices have reduced the presence of this parasite in pork, and with education on proper cooking and/or freezing of pork, the incidence of trichinosis has been greatly reduced.
T. nativa is found in artic and subartic areas in wild carnivores and omnivores, such as bears, wolves, cougars, walrus, and foxes. A number of other species have been identified in other wild carnivores around the world.
Prevention can be accomplished by cooking meat products to an internal temperature of 170 degrees Fahrenheit or by freezing pork products less than 6 inches thick at 5 degrees Fahrenheit for 20 days. T. nativa and other Trichinella are considered less sensitive to freezing. Cooking of garbage fed to swine as well as preventing swine from consuming rat carcasses are important practices in reducing the infection in swine. Salting, drying, smoking, and/or microwaving are not reliable methods of destroying infective cysts.
No cases of trichinosis were reported to the Indiana State Department of Health (ISDH) from 1998-2002.
Nationally during 1997-2001, 72 cases of trichinosis were reported:
32 from consumption of wild game
29 from bear meat
1 from cougar meat
1 from wild boar meat
12 from consumption of commercial pork products
4 from imported products
9 from consumption of non-commercial pork products
20 cases had an unknown source of infection
You can learn more about trichinosis by visiting the following Web sites: