These tapeworms are parasites of dogs, foxes and dingoes. Dogs become infected by eating meat or offal containing cysts. Hydatid cysts of Echinococcus granulosus can cause life threatening disease of humans. Cysticercus have a single white head enclosed in a membrane. Cysts several cm in diameter.
Cysts occur in live, lung or occasionally brain and other tissues.
The hydatid cysts of E. granulosus have thick walls, may contain smaller cysts, and contain many small heads, giving a sandy consistency. Click for a map of distribution of sheep larval cestodes in Australia. The likelihood of infection is increased by the proximity of wild dogs, access by intermediate hosts to infected dogs' faeces and cool climates which favour survival of eggs and cysts in the environment. The map indicates areas of high and low likelihood of infection being transmitted, but outbreaks can occur anywhere there appropriate hosts and the parasite come together. Sheep are the intermediate hosts of the cystic stages of the 3 dog tapeworms.