Several people developed rashes after swimming at Lake Mead's Boulder Beach over the weekend, and the National Park Service said waterfowl may be to blame.
Officials at Lake Mead National Recreation Area said the poison-ivy-like reactions reported by nine swimmers so far are most likely a rash known as swimmer's itch, which is spread to humans by a parasite found in bird feces.
Rangers have noticed a larger than normal number of waterfowl in the water and along the shoreline at Boulder Beach.
Water quality tests will be conducted to try to confirm the source of the rashes, but the beaches at Lake Mead remain open.
Visitors who see excess waterfowl droppings on shore are advised to stay out of the water. If you do swim, it is best to towel dry afterward.
Most cases of swimmer's itch do not require medical attention. If a rash develops after swimming, the park service recommends first-aid treatments such as anti-itch lotion or corticosteroid cream.
More information on swimmer's itch is available on the Center for Disease Control's website, www.cdc.gov/parasites/swimmersitch.
Contact reporter Henry Brean at firstname.lastname@example.org or 702-383-0350.