Ringworm is a contagious fungus infection that can affect the scalp, the body, the feet (athlete's foot), or the nails.
People can get Ringworm from: 1) direct skin-to-skin contact with an infected person or pet, 2) indirect contact with an object or surface that an infected person or pet has touched, or 3) rarely, by contact with soil.
Ringworm can be treated with fungus-killing medicine.
To prevent Ringworm, 1) make sure all infected persons and pets get appropriate treatment, 2) avoid contact with infected persons and pets, 3) do not share personal items, and 4) keep common-use areas clean.

Here's a source of good information for treatment
ringworm