Swimmer's itch is commonly, but incorrectly, called "chiggers," because of the similarity of the symptoms between the two conditions.
Chiggers are six-legged mite larva that live in tall grass or weeds. They are parasites of humans and animals. Chigger bites produce inflamed welts on the skin.
Swimmer's itch produces the same inflamed welts, though from a different source. When the water temperature reaches about 60 degrees, cercaria (flat worm larva) are released from snails. The parasites then begin to search for a host. Because they cannot swim, they rely on wind and currents to transport them.
The natural host of the cercaria are birds and waterfowl. They will also try to attach to humans if they come in contact with them. They do this by attempting to burrow under the skin. The human immune system responds by killing the cercaria, and itchy welts flare up on the skin.
Contact with the cercaria is not dangerous, and will not cause any diseases. The discomfort of the welts is the only symptom.
Gilbertson of the Department of Natural Resources fisheries office in Spicer, recommends several things to reduce the chance of getting swimmer's itch.
•Avoid swimming or wading in shallow water near shore.
•Towel off immediately after leaving the water.
•Avoid swimming on days when there is an on shore breeze blowing toward your property.
•Do not encourage waterfowl to loaf on your dock.
Copper sulfate can be used to treat areas where swimmer's itch becomes a problem. Treatment with this chemical requires a permit from the DNR.
Autumn Roemeling, lifeguard at Veteran's Memorial Park, said swimmer's itch has not been a problem this summer. Some incidences occurred and were reported before the beach officially opened, so the city treated the water. It hasn't been a problem since.
Zac Spates, head lifeguard at the Lake Koronis Assembly Grounds, came into contact with swimmer's itch in May, when he was putting docks in at the Grounds. He got over 200 welts on his body.
Spates said the severity and duration of a case of swimmer's itch depends on the sensitivity of the individual. "I've gotten it three years in a row now," he said. "Some people don't even get it. It just depends on how allergic you are."
The Assembly Grounds staff treats the water twice a summer with copper sulfate. This eliminates the problem.
"We're going to start treating the water every spring now because it's there every year," said Spates.
Though these two Lake Koronis beaches have the problem under control, cases of swimmer's itch have sprung up around private residences.
Kristine Potratz has a cabin on Little Sandy Point. She got a bad case of swimmer's itch last Wednesday. She swam in the morning following a storm with high winds.
Gilbertson explained why this happened. "Since cercaria can't swim, a wind shift can allow them to move," he said. "When wind is coming into a beach, it's a bad time for encountering them."
Other area lakes, like Long and Rice, have not had any problems with the condition this year.
"It is something that people are going to encounter when in a natural setting," said Gilbertson. "If we swim in lakes, we're going to experience it. The best thing we can do is try to reduce the incidence and severity."