Northwoods lakes are a natural draw for swimming and other water activities on a hot summer’s day. But an occasional side effect can come from such lake water fun. In some Wisconsin lakes, swimmer’s itch can occur.
Swimmer’s itch is an allergic reaction to a parasite called a schistosome. “The parasite is present in the feces of waterfowl such as ducks or geese,” said Pediatrician Sanjeev Jain, M.D., Marshfield Clinic Minocqua Center. “With the help of snails it reproduces and is released into the water in search of a host bird or mammal. It gets stuck to the skin and produces an allergic reaction that results in a bothersome, itchy rash.”
Symptoms of swimmer’s itch include a red pimple type of rash, intense itchiness, and sometimes burning, tingling or small blisters. “The parasite cannot survive in humans,” said Dr. Jain. “It will die within 24 hours. Symptoms usually appear within 24 hours of exposure to the parasite and will last only for a few days.”
There is no prescribed treatment for swimmer’s itch. “To relieve the itching, I suggest soaking the affected area with a cool compress or applying an anti-itch or hydrocortisone cream,” Dr. Jain said. “Try to avoid lake water swimming, wading or other water activities until the rash has cleared. Returning to the water site where the parasite is suspected could cause a more severe rash to occur.”
Swimmer’s itch begins to appear in May and June and becomes more common during the height of summer. When it does occur in a particular lake, it is more likely to be present in shallow water or near the beach.
Swimmer’s itch may be confused with other lake water problems or medical conditions:
It is unrelated to high bacteria count problems that occur in some lakes.
It cannot be caught at a swimming pool because of pool chlorination.
It is not contagious. The allergic reaction cannot be passed from person to person.
Keep swimmer’s itch from spoiling your water fun. Towel dry or take a shower immediately after swimming in lake water. Avoid feeding and thereby attracting birds to beach areas. Steer clear of areas in lakes known to have high incidence of swimmer’s itch.
“If you are uncertain whether the rash has been caused by swimmer’s itch, see your doctor,” said Dr. Jain.