Swimmer's Itch (cercarial dermatitis, schistosome dermatitis)

Last Reviewed: November 2006

What is swimmer's itch?

Swimmer's itch is a skin rash caused by certain parasites of birds and mammals. These parasites are released from infected snails and migrate through waters, including those used for recreational swimming. Cases of swimmer's itch have been reported from all parts of New York State.

Who gets swimmer's itch?

People who swim or wade in infested water may experience this itching rash. All age groups and both sexes can be involved, but children are most often infected because they are more likely to swim or wade in the water and play on the beach as the water evaporates from the skin.

How is swimmer's itch spread?

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

What are the symptoms of swimmer's itch?

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 itching will subside for 10-15 hours and may then become extremely intense. This itching stage usually disappears within a week.

How soon do the symptoms begin?

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

What is the treatment for swimmer's itch?

While all cases do not require treatment, some people may seek relief by applying specific skin lotions or creams to minimize the itching.

What can be done to prevent the spread of swimmer's itch?

Toweling off after swimming or wading in infested water can be very helpful in preventing rash development. Communities may apply through the New York State Department of Environmental Conservation for a permit to apply specific chemicals to kill the migrating snails. Copper sulfate or copper carbonate materials can be applied by boat around popular bathing areas. If properly timed, these applications may prevent the annual migration of infested snails into swimming areas.