Echinococcus granulosus is a parasitic tapeworm that primarily affects canines, such as dogs and wolves, as its definitive hosts. The adult worms live in the intestines of these animals, where they produce eggs that are excreted in feces. Humans can become accidental hosts by ingesting the eggs, often through contaminated food or water. In humans, Echinococcus granulosus can cause a disease known as hydatid disease, characterized by the formation of cysts in organs like the liver and lungs. These cysts can grow over time and may lead to serious health complications if not treated. Proper hygiene and sanitation are essential to prevent transmission.