Cystic echinococcosis (CE) is caused by an infection from the larval stage of Echinococcus granulosus. CE is found in Africa, Europe, Asia, the Middle East, Central and South America, and in rare cases, North America. The parasite is transmitted as dogs ingest the organs of other animals that contain hydatid cysts and pass the parasite to sheep, cattle, goats, and pigs from eggs released in its’ fecal matter. The most common mode of transmission to humans is by the accidental consumption of soil, water, or food that has been contaminated by the fecal matter of an infected dog, depositing Echinococcus eggs that can stay viable for up to a year. Additionally, eggs released in an infected dog's stool can end up in its fur; close contact with the hair of an infected dog through handling, petting and playing may result in transmission to humans. The disease is most commonly found in people involved in raising sheep, as a result of the sheep’s role as an intermediate host of the parasite.

Alveolar echinococcosis (AE) is caused by an infection from the larval stage of Echinococcus multilocularis. AE is found across the globe and especially prevalent in the northern latitudes and includes Europe, Asia, and North America. Although rare in humans, the parasite normally found in foxes, coyotes, and dogs can be transmitted to people through ingestion of food or water contaminated with eggs or by handling dogs that picked up eggs in their fur from feces.