I found this info on a medical web,
http://www.cvm.uiuc.edu/petcolumns/showarticle.cfm?id=408, site about ringworm:
"Ringworm is very badly named because it is caused by a fungus not a worm," says Dr. John Angus, a veterinary dermatologist at the University of Illinois Veterinary Teaching Hospital in Urbana. "Ringworm makes its home on the hair and skin, and it affects both people and pets. In humans, ringworm forms a ring-shaped, raised red rash, but this presentation is not common in animals. Ringworm can look like anything!"
Dogs and cats are susceptible to three forms of ringworm. Our feline friends are the reservoir for the most common form of ringworm in pets. Second in line is carried by rodents and picked up by nosy dogs digging through rodent burrows. The third form is a soil fungus.
It is possible to contract ringworm from your kitty. Studies show that in 30 percent to 70 percent of households where the cat has ringworm, at least one person will get it. However, humans have our own forms of ringworm. Athlete's foot is the classic example. Only 3.3 percent of all human cases are caused by the same fungus that infects dogs and cats, so you are far more likely to get ringworm from the playground or weight room than from your furry friends.
"People with the highest risk for catching ringworm from their pet are young children who have never been exposed, the elderly, or people with a depressed immune system," comments Dr. Angus. Once humans have been exposed to a strain of ringworm, most people develop immunity and rarely get the same strain again.
"It's important to know you have ringworm in your home. If your pet has patchy hair loss or any crusty bumps, take it to your veterinarian for a fungal screen. It is a good idea to screen all new pets, particularly strays, before introducing them to your current animals."