Echinococcus granulosus is a parasitic tapeworm that primarily infects canines, such as dogs and wolves. It causes a disease known as hydatid disease in humans and other animals. The adult tapeworm resides in the intestines of its definitive hosts, where it produces eggs that are excreted in feces. Humans can become accidental hosts by ingesting the eggs, often through contaminated food or water. Once inside the body, the eggs hatch and form cysts, usually in the liver or lungs, leading to serious health complications if not treated.