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Swimmer's Itch

What is swimmer’s itch?


Swimmer’s itch is a skin rash that affects some people that swim in bodies of water, including Shawano Lake. Following is information that was provided by the Wisconsin Department of Health Services.


Swimmer’s itch is a skin rash caused by a parasite which ordinarily infects birds, semi-aquatic mammals, and snails. As part of their developmental life-cycle, these parasites are released from infected snails, migrate through the water, and are capable of penetrating the skin of people. After penetration, these parasites remain in the skin and die but can cause an allergic reaction in some people. The parasite in people does not mature, reproduce or cause any permanent infection.


Only about one-third of the people who come in contact with the parasite develop swimmer’s itch. People who swim or wade in infested water may experience this itchy rash. All age groups and both sexes can be involved, but children are most often infected due to their habits of swimming or wading in shallow water and playing on the beach as the water evaporates form their skin. Swimmer’s itch may be prevalent among bathers in lakes in many parts of the world.


An individual may get the infection by swimming or wading in infested water and then allowing water to evaporate off the skin rather than drying the skin with a towel. Person-to-person spread does not occur.


Whenever infested water is allowed to evaporate off the skin, an initial tingling sensation may be felt associated with the penetration of the parasite into the skin. The irritated spot reaches its maximum size after about 24 hours; the itching may continue for several days. The symptoms should disappear within a week.


A person’s first exposure to infested water may not result in the itchy rash. Repeated exposure increases a person’s allergic sensitivity to the parasite and increases the likelihood of rash development. Symptoms may appear within one to two hours of exposure.

There is no treatment necessary for swimmer’s itch. Some people may get relief from the itching by applying skin lotions or creams to the infected site.


The first outbreaks usually occur in late May or early June. The outbreaks in Wisconsin may last from two weeks in the northern lakes to a month in the southern lakes. In some lakes it may last the entire summer.


To reduce the chances of getting swimmer’s itch:


  • Towel off immediately after swimming or wading in infested water to prevent rash development.

  • Swim in water away from the shore.

  • Avoid swimming in areas where snails have accumulated.

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


Other tips from Shawano Lake veterans: apply Vaseline or soap before entering the lake and towel off as soon as you leave the water. Wash off with Phels Naptha soap immediately.

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