Swimmer’s Itch Reported in Door County

Mosquitos, ticks, poison ivy – oh, my! None of that sounds fun, but with the best parts of summer, you have to take some of the worst.

You know what else doesn’t sound fun? 

Parasites and swimmer’s itch.

Parasites cause an itchy skin rash called swimmer’s itch, or cercarial dermatitis, which has been reported in Door County – specifically, in Clark Lake just south of Jacksonport.

Chelsea Smies, a registered sanitarian and health educator with the Door County Department of Health and Human Services, explained that the itch is not communicable – it does not spread from person to person – so those affected are not required to notify public-health officials.

“This is not to discourage anyone from going to Clark Lake or any other inland lakes,” Smies said. “Swimmer’s itch is said to be a nuisance, but it is actually a sign of a diverse and healthy outdoor environment.”

Because it’s not a reportable disease, the number of individuals infected is not known. It’s also hard to identify because it can look like other bug bites. Health-services professionals urge people to take precautions – and there are ways to prevent the itch.

But let’s discuss the symptoms first. When lake water evaporates from the skin, an initial tingling sensation may be felt, which is associated with the parasites penetrating the skin. The resulting rash involves red, bite-like welts that appear within hours. Once the parasite infects a person, however, it cannot develop further or reproduce – it simply burrows into the skin and dies. Good riddance!

The itch can last for several days, but it should be clear within a week. There is little that can be done to get rid of it, but lotions such as calamine can be soothing. Sometimes symptoms don’t occur unless a person repeatedly enters infected water.

To increase your chances of preventing the rash:

• Remove the parasite by toweling off and showering right after leaving the water.

• Swim in water away from the shore.

• Avoid areas where bird or animal feces or snails have accumulated.

• Don’t encourage birds to stay near swimming areas by feeding them.

• Don’t swim near storm drains.

• Read signs. If a sign says the area is closed, don’t swim there. Smies says almost all public beaches are monitored, and anyone can check beaches’ status at

According to the Wisconsin Department of Health Services, the parasite ordinarily infects birds, semiaquatic mammals and a particular snail. Once the parasite infects birds and mammals, it lays eggs, which are then passed through the feces into the water. When snails become infected, the parasite develops and is released again into the water to swim freely. Though the parasite normally seeks bird or animal hosts, it can also penetrate the skin of humans.

Anyone who swims or wades in infected waters can develop the itch, no matter the age or sex, but children may be at higher risk because they tend to wade in shallow water and may forget to dry off with a towel upon exiting. About one-third of people who come in contact with the parasite develop the rash.

Courtesy of the CDC.

The parasite is found beyond the Great Lakes region in waters around the world, and shallow waters tend to be more affected because snails typically live near shorelines. Smies said nothing can eliminate the parasites from the water.

She also said the parasite appears most commonly in warm waters, which is why smaller, inland lakes produce more swimmer’s itch. Temperature, rain, sunlight and wind all play a role, and an infected area can be rid of the parasite within hours because it moves quickly.