I'm not sure if you're thinking about tapeworms - ringworm is picked up through the skin (still really nasty) while tapeworms are picked up through ingestion.
Tapeworms can live in the intestinal tract of almost any living creature. They lay their eggs around the edges of the anus and the eggs either drop away from the carrier in feces, are wiped off on something or are reingested as the animal cleans itself.
Tapeworms can be generally detected in several ways - adult worms crawling in feces, adult body sections that have broken off and stick to the animal's fur (look like moist oatmeal kernals), or because the animal rubs its ass consistantly against things (like dogs drawing their bottoms along the floor) because the eggs itch.
To prevent yourself from accidental ingesting tapeworm eggs, always be sure to wash your hands before eating - especially after handling animals or even petting a passing dog. Wash any areas that a pet dog (etc.) may have licked, such as your face, as well. Changing clothing after handling wild or poorly kept animals, especially before eating is also a good idea as eggs or worm sections could follow you. And lastly, never "share" food with an animal - letting a dog lick your ice cream cone or giggling when that cute monkey comes up and snatches something from your plate - the creature could very easily leave you an extra "treat" without ever meaning to.
As for cures, I've heard of an old one that features eating lots of carrots and brown sugar and another that involves ingesting tobacco, but quite frankly I'd visit a doctor
Stay alert - stay healthy - stay alive.
