When human swimmers leave the water, any parasites on their skin may burrow into the skin in an effort to survive. The parasites die quickly, but they can trigger an irritating rash, said Joshua Meyerson, MD, Medical Director of the Health Department of Northwest Michigan. "Your body reacts to the parasite by forming itchy, red bumps,” he said. “Swimmers' itch isn’t contagious, but it is very annoying."
To reduce the chances of developing swimmer's itch, briskly dry off with a towel as soon as you come out of the water, including under swimsuits. Where facilities are available, shower immediately after swimming.
Swimmers' itch symptoms can appear within minutes or up to a week after swimming in lake water. A small, reddened bump will develop at the entrance site of each parasite, causing periods of itching that can last for several days. Using calamine lotion, an antihistamine such as Benadryl or corticosteroid cream, cool compresses, baths with baking soda or colloidal oatmeal, such as Aveeno, may control itching.
“The most important thing to do if you do contract swimmers' itch is to try not to scratch. Scratching may cause the rash to become infected. If itching is severe, your health care provider may prescribe lotion or creams to lessen your symptoms,” Meyerson said.
Not everyone who is exposed to the parasite will necessarily develop swimmers' itch. “Repeated exposure increases sensitivity to the parasite and increases the likelihood of swimmers' itch,” Meyerson said. Children are often infected with swimmers' itch since they typically wade in and out of the water and play on the beach as water evaporates on their skin.
Most cases of swimmers' itch do not require medical attention. Contact your health care provider when the diagnosis is unclear, complications such as infection are present, or the reaction is intolerable.
The Health Department of Northwest Michigan is mandated by the Michigan Public Health Code to promote wellness, prevent disease, provide quality healthcare, address health problems of vulnerable populations, and protect the environment for the residents and visitors of Antrim, Charlevoix, Emmet, and Otsego counties. For additional information about swimmers' itch, visit http://www.cdc.gov/ncidod/dpd/parasites/cercarialdermatitis/2004_PDF_Cercarial_Dermatitis.pdf or contact your health care provider.