The truly serious tapeworm species is called Echinococcus. Both of these tapeworms can cause serious, even fatal disease in humans through hydatid cysts. Echinococcus granulosus is in its most aggressive form in sheep. If a dog eats uncooked meat or offal from an infected sheep and then defecates in the pasture, the life cycle for this parasite is perpetuated. Humans are most often infected through contact with their own pets.
Personal hygiene is obviously of the utmost importance here.
Sheep-herding dogs imported to the United States from Australia must undergo quarantine. In Australia, wallabies and dingoes help perpetuate the cycle, as well as the sheep and dog relationship. So, while tapeworms are not usually a serious parasite, they can cause some health problems. They're reasonably easy to treat and you, as an owner, are an important partner in diagnosing it. And then there's that question of how your dog got infested and how you can change that.