a helminthic disease of humans and animals caused by a tapeworm (cestode). In man helminths are parasitic in the intestine (for example, adult tapeworms and the broad fish tapeworm) and various other organs and tissues. The larval stages of Echinococcus, Alveococcus, and Cysticercus concentrate in the liver, brain, and eyes. Infection occurs after the parasite’s eggs (for example, the dwarf tapeworm and Echinococcus) or larvae (for example, beef and pork tapeworms) enter the alimentary canal. Infestation causes gastrointestinal disorders, anemia, and disturbances of the liver, nervous system, eyes, and other organs and systems. The most common cestodiases affecting humans are diphyllobothriasis, hymenolepiasis, teniasis, and echinococcosis.

Cestodiases of animals are caused chiefly by cestodes of the two orders Pseudophyllidea and Cyclophyllidea. The season when infestation takes place and the site where the parasites concentrate vary with the species of the causative agent. Adult cestodes may be parasitic on the intestinal mucosa, causing it to become inflamed. In echinococcosis the larval stages of the cestodes form cysts in the liver, and the larvae continue to live inside the cysts. In coenurosis cysts develop in the brain, intermuscular tissue, and subcutaneous tissue; the symptoms of the disease vary with the organ or tissue affected. Intestinal cestodiases are associated with diarrhea. In sheep coenurosis of the brain causes the animals to move involuntarily in a circle and throw their head back. Echinococcosis produces pain in the liver region. Diseased animals grow slowly, become emaciated, and sometimes die. Prevention requires worming of the animals and observance of sanitary rules in their maintenance.