What is it?
An allergic reaction to microscopic parasites found in lakes, ponds, and oceans that are infested with the feces of ducks, geese, gulls, and other animals.
What to look for
Tingling, burning, or itching on uncovered areas; tiny, red pimples that last about a week.
What to do
The rash will fade on its own, but apply hydrocortisone cream and cool compresses to relieve itching.
How to prevent it
Don't let your child swim or play in shallow water (snails, which spread the parasite, are commonly found there). Have him shower immediately after leaving the water.