In rare cases, swallowing a live nematode larva can cause severe gastric upset called anisakiasis. This happens when the nematode attaches to or penetrates the intestinal lining. Nematodes do not find humans to be suitable hosts and will not live longer than 7-10 days in human digestive tracts. Swallowing live tapeworm larvae can cause a tapeworm infestation. The tapeworms may live in the human intestinal tract for several years.
Symptoms can include abdominal pain, weakness, weight loss and anemia.
Doctors successfully treat tapeworm infections with medicines. Cooking fish to an internal temperature of 140 F will kill all fish nematodes and tapeworms. Normal cooking procedures generally exceed this temperature. Heating hot-smoked fish to an internal temperature of at least 140 F will kill all fish nematodes and tapeworms. Normal hot-smoking procedures generally exceed this temperature.