Authorities say several cases of swimmer's itch have been reported in persons wading or swimming in Saguaro Lake northeast of Phoenix.
Health officials say swimmer's itch is a rash caused by a tiny bird parasite that can occur in natural bodies of water and have been reported in lakes throughout Arizona.
It's also known as cercarial dermatitis and lake itch.
People can be exposed when swimming or wading in the shallow, marshy parts of the water.
Symptoms consist of itchy reddish pimples and/or blisters that occur only on portions of skin that are submerged in water and can persist for a few days up to a few weeks.
Health officials say the rash goes away without treatment and symptoms are most commonly treated with topical creams or lotions.