What is it?
An infection that's caused by a fungus known as tinea, not by a worm. Kids can catch it from other children, animals (especially kittens), or soil.
What to look for
On the scalp, it causes hair loss, leaving itchy, round, red patches. Infected skin becomes scaly and red; your child may develop a ringlike lesion with a raised border and a clear center.
What to do
For scalp ringworm, see your doctor, who will prescribe an antifungal oral medication; over-the-counter creams often resolve skin infections in two to four weeks.
How to prevent it
Teach your kids not to share hats, brushes, barrettes, or towels; avoid contact with infected individuals or animals.