Officials are warning people visiting some of Iowa's natural lakes about a condition called swimmer's itch.
The state Department of Natural Resources says reports of swimmer's itch have come in from Crystal Lake and Black Hawk Lake. The condition is caused by a parasite that can burrow into human skin before dying.
The DNR says the condition can create welts and itching and last for several days.
People visiting beaches and natural lakes should avoid swimming in areas with aquatic plants. Swimmers should also reduce their amount of time in the water, and dry off quickly after getting out of the water.