Echinococcus granulosus is a tapeworm parasite that in its larval form can cause hydatid disease, which is characterized by cysts forming within the victim's body. In order to complete its lifecycle, the tapeworm must infect two hosts, a carnivore and a herbivore.
The adult form of Echinococcus granulosus exists benignly in carnivores, which are primarily infected by eating the raw or undercooked internal organs of other animals that contain hydatid cysts. The tapeworm larvae that fill the cyst are released into the animal's body after the cyst wall is digested. The larvae attach themselves to the intestines, where they grow into egg-producing adults. When the eggs are passed outside the body with excretory material, they may then by digested by grazing animals. The eggs hatch within the herbivorous host and travel throughout the body, settling into tissue and developing into cysts.