Body is thin and soft, and is flattened dorsoventrally. Body is cylindrical in shape, tapered at the end and unsegmented. Most infestations are diagnosed by identification of the ova present in the feces or the perianal region, with the exception of trichinosis, which is diagnosed by the presence of adult Trichinella worms in the feces. This parasite inhabits the bile ducts, gallbladder and pancreatic ducts of humans, causing biliary cirrhosis and jaundice.
Human infection occurs by the ingestion of larvae when eating raw or undercooked freshwater fish.
This tapeworm can be found in dogs, and may be present in large numbers. A dog can acquire the parasite by eating the infested viscera of another animal. Dogs will then shed the ova, which is infective to humans, in their feces. The larval stage of echinococcus is called the hydatid cyst. The cyst stage causes hydatid disease, which can be quite serious.