Although annoying, these worms do not cause any serious disease. Trichinosis, a roundworm infection that is not transmitted through feces, remains a problem in this country. Most cases arise from eating undercooked pork containing the larvae of the trichinae worms. These larve mature in the intestines and burrow through the body to muscles, where they form new cysts. Light infections do not cause symptoms, and many people who were never known to have trichinosis can be found to harbor the cysts if carefully examined during an autopsy.
Heavy infections can cause serious disease and even be fatal.
Most cases now arise from homemade pork products, such as sausage, which have not been totally cooked. Thorough cooking, freezing pork at -15 degrees centigrade for three weeks, or radiation treatment will all kill the larvae. There have been reports in recent years of more exotic roundworm infections that people have caught from eating sushi. Many worm infections do pass through fish, especially freshwater fish. Sushi that is prepared by an inexperienced chef can contain the larvae of the worm.