A parasitic flatworm causes swimmers itch. (CDC photo)
Here’s another sign that summer is arriving in Iowa — reports of swimmer’s itch have been increasing.
DNR fisheries biologist Mike Hawkins says swimmer’s itch is a common issue on Iowa lakes. “Some years are better than others. This year looks like it could be a good year for swimmer’s itch — or bad — given your perspective,” Hawkins says.
He says the itchiness is caused by the microscopic parasitic flatworm. “The flatworm has a pretty interesting life cycle. It goes from a bird through bird droppings into the water and from there a snail ingest the eggs. The eggs develop in the snail and the larvae emerge from there and try to go back to the bird. So, kind of an interesting organism, kind of a complex life cycle,” Hawkins explains.
The larvae end up trying to get under the skin of swimmers if birds are not available. Hawkins says the human body fights off the larvae, but it ends up being an itchy situation. Water that’s dirty or full of pollutants is usually what you want to avoid when swimming — but in this case — Hawkins says the cleaner lakes are the ones where you’ll find swimmer’s itch.
“Typically our best lakes in Iowa and across the midwest have healthy snail populations. So, clear water, lots of aquatic plants, those are the lakes that we’ll typically see more swimmer’s itch in,” according to Hawkins. “So, in a way, swimmer’s itch is an indication of good water quality in some of our lakes.” He says swimmer’s itch usually is the biggest problem between Father’s Day and the Fourth of July. There are some things swimmers can do to avoid the problem.
“You probably should stay away from the areas where the waves have been pounding in for a day or two or more. That tends to accumulate debris, but also that larvae that is in the water,” Hawkins says. “So avoiding those areas is probably the best thing you can do. Swimming in deeper water, open water, is better than wading at the shore.” He says be sure to take some precautions when are done swimming.
“Toweling off and rinsing off when you get out of the water is important to try and get the water off of your skin. The swimmer’s itch tends to concentrate in those little water droplets in the skin and that’s where they’ll try to make entry,” Hawkins says. He says it’s a problem that can happen all across the state, but they are seeing many reports now in the Iowa’s Great Lakes and surrounding northwest and north central Iowa lakes.