Tinea capitis, also known as scalp ringworm, is a highly contagious but treatable skin infection on the scalp. It is not actually a worm of any sort. The infection earned its name from the marks it leaves on the skin: ring-shaped patches. These patches can be patches of lost hair, scaly pink rashes, or irritated, pus-seeping sores. Children most commonly suffer from scalp ringworm, so you should keep an eye on your child's scalp and tell your doctor if you notice any of these patches.