This is a common and widespread intestinal worm.While light infections are usually asymptomatic, autoinfection through eating the eggs of worms in the intestines is possible, and it can lead to hyperinfection. Humans can also become hyperinfected through ingesting grain products contaminated by infected insects. Infections involving more than two thousand worms can cause many different gastrointestinal symptoms and allergic responses. Common symptoms include chronic urticaria, skin eruption, and phlyctenular keratoconjunctivitis. Diphyllobothriasis
Diphyllobothriasis is caused by infection with Diphyllobothrium latum (also known as the "broad tapeworm" or "fish tapeworm") and related species. Humans become infected by eating raw, undercooked, or marinated fish acting as a second intermediate or paratenic host harboring metacestodes or plerocercoid larvae.Clinical symptoms are due to the large size of the tapeworm, which often reaches a length exceeding 15 m (49 ft). The most common symptom is pernicious anemia, caused by the absorption of vitamin B12 by the worm. Other symptoms include various intestinal issues, slight leukocytosis, and eosinophilia. Sparganosis
Sparganosis is caused by the plerocercoid larvae of the tapeworm Spirometra. Humans become infected by drinking contaminated water, eating raw or poorly cooked infected flesh, or from using poultices of raw infected flesh (usually raw pork or snake) on skin or mucous membranes.The most common symptom is a painful, slowly growing nodule in the subcutaneous tissues, which may migrate. Infection in the eye area can cause pain, irritation, edema, and excess watering. When the orbital tissues become infected, the swelling can cause blindness. An infected bowel may become perforated.
Brain infection can cause granulomas, hematomas, and abscesses. Subdivisions
The evolutionary history of the Eucestoda has been studied using ribosomal RNA, mitochondrial and other DNA, and morphological analysis and continues to be revised. "Tetraphyllidea" is seen to be paraphyletic; "Pseudophyllidea" has been broken up into two orders, Bothriocephalidea and Diphyllobothriidea. Hosts, whose phylogeny often mirrors that of the parasites (Fahrenholzs rule), are indicated in italics and parentheses, the life-cycle sequence (where known) shown by arrows as (intermediate host1 [→ intermediate host2 ] → definitive host). Alternatives, generally for different species within an order, are shown in square brackets. References

Bale, James F. "Cysticercosis." Current Treatment Options in Neurology. 2000. pp. 355–360. Dunn, J., and Philip E. S. Palmer. "Sparganosis." Seminars in Roentgenology. 1998. pp. 86–88. Esteban, J. G., Munoz-Antoli, C., and R. Toledo. "Human Infection by a "Fish Tapeworm," Diphyllobothrium latum, in a Non-Endemic Country." Infection. 2014. pp. 191–194. Kim, Bong Jin, et al. "Heavy Hymenoleptis nana Infection Possibly Through Organic Food: Report of a Case." The Korean Journal of Parasitology. 2014. pp. 85–87. Mehlhorn, Heinz. "Eucestoda Classification." Encyclopedia of Parasitology. 2008. pp. 495–497. Rohde, Klaus. "Eucestoda." AccessScience. McGraw-Hill Ryerson. Usharani, A., et al. "Case Reports of Hydatid Disease." Journal of Epidemiology and Global Health. 2013. p. 63–66.