Humans develop diphyllobothriasis, an infection caused by fish tapeworm, when they ingest raw or undercooked fish. Although the fish tapeworm is native to Scandinavia, the Baltics, and western Russia, the parasite is now present in the United States, especially in the Pacific Northwest. The Diphyllobothrium latum, another name for the fish parasite, is the largest tapeworm to infect humans and averages 33 feet in length.
The life cycle of a fish tapeworm begins and ends with humans, or other larger hosts such as dogs and bears. The life cycle involves:
Unembryonated eggs passing in the feces of a human or animal and finding their way to a pond or lake.
Once in water, the eggs will embryonate.
Coracidia hatch from the eggs and are consumed by crustaceans.
While in the crustaceans, the coracidia becomes a procercoid larva.
Small freshwater fish then eat those crustaceans, and the procercoid larva is released from the crustaceans to become plerocercoid larva.
Larger, predator fish eat the smaller, infected fish.
Humans and animals are infected after they eat those large fish raw or undercooked.
Often those who are infected with these fish parasites don't know it since the infection is usually asymptomatic. However, some may experience diarrhea, dizziness, vomiting, fatigue, abdominal pain, and numbness of the fingers and toes. If you suspect you have fish tapeworms, contact your physician. Your doctor may simply require a stool sample to see if there are any characteristic fish tapeworm eggs in your feces. If worms are found, you will usually receive a treatment of an anthelmintic.
Humans develop diphyllobothriasis, an infection caused by fish tapeworm, when they ingest raw or undercooked fish. Although the fish tapeworm is native to Scandinavia, the Baltics, and western Russia, the parasite is now present in the United States, especially in the Pacific Northwest. The Diphyllobothrium latum, another name for the fish parasite, is the largest tapeworm to infect humans and averages 33 feet in length.
