Tapeworm infection is caused by ingesting food or water contaminated with tapeworm eggs or larvae. If you ingest certain tapeworm eggs, they can migrate outside your intestines and form larval cysts in body tissues and organs (invasive infection). If you ingest tapeworm larvae, however, they develop into adult tapeworms in your intestines.
A variety of parasitic infections might be acquired by ingesting raw or undercooked fin fish. Fish tapeworm, or Diphyllobothrium spp, is acquired by eating raw or undercooked freshwater or anadromous fish. Very thin slices of raw fish common in Italy. The extrapolated prevalence in italy, is found to be 15,032 for two times of 8,174,562 population estimation used..