Diseases and afflictions that can be passed on from dogs to humans are called zoonotic diseases. The most common zoonotic afflictions come from fleas and ticks that jump from dogs to their owners. However, dog worms such as roundworms and tapeworms can also infect humans under the right circumstances.
The most common form of tapeworm that can jump from dog host to human host are canine tapeworms. In dogs, these parasitic creatures live inside the digestive tract of the animal and leach the nutrients that the dog consumes. When the dog defecates, oftentimes tapeworm eggs and larvae can accompany the feces. If an adult or especially a child comes into contact with this feces and somehow ingests it (such as not washing before eating a meal), the eggs can hatch and grow inside the new human host. Once hatched, the larvae will grow into hydatid cyst in the liver and other surrounding organs. The cysts will continue to grow to as much as a foot in length and in most cases will need to be surgically removed.
Another type of tapeworm that can be transferred from humans to dogs is the flea tapeworm. These tapeworms are much harder to catch as the an infected flea from a dog must be swallowed by the human for the larvae to survive, hatch and infect the new host. Most commonly this occurs in children. Flea tapeworms do not grow to be as large as canine tapeworms but can still leach nutrients from the body creating potentially serious health problems.
The best way to prevent a canine to human transmission of tapeworms is to keep your dog on a regular de-worming schedule. Keeping them protected against worms will also prevent worms from infecting you. If your dog is allowed to roam free on a farm or large area of property, preventing them from eating dead wild animals will also help keep down chances of the dog contracting a tapeworm.