Swimmer’s Itch

beach-signSwimmer’s itch, also called cercarial dermatitis, is a skin rash caused by an allergic reaction to certain microscopic parasites that infect some birds and mammals. These parasites are released from infected snails into fresh and salt water such as lakes, ponds, and oceans. If the parasite comes into contact with a swimmer, it burrows into the skin causing an allergic reaction and rash. Swimmer’s itch is found throughout the world and is more frequent during summer months.

Symptoms of swimmer’s itch

  • Tingling, burning, or itching of the skin within minutes up to days after swimming in contaminated water
  • Small reddish pimples may appear within 12 hours
  • Small blisters may develop

Scratching the areas may result in secondary bacterial infections. Itching may last up to a week or more, but will gradually go away. If itching is severe, your health care provider may prescribe lotion or creams to lessen your symptoms. If your symptoms persist, see your doctor.

Because swimmer’s itch is caused by an allergic reaction to infection, the more often you swim or wade in contaminated water, the more likely you are to develop more serious symptoms. The more times you are exposed to contaminated water, the more intense and immediate the symptoms of swimmer’s itch will be.

Avoid getting swimmer’s itch

  • Do not swim in areas where swimmer’s itch is a known problem or where signs have been posted warning of unsafe water.
  • Avoid swimming near or wading in marshy areas where snails are commonly found.
  • Towel dry or shower immediately after leaving the water.
  • Do not attract birds by feeding them to areas where people are swimming.

Children are more at risk for Swimmer’s Itch

Anyone who swims or wades in infested water may be at risk. Larvae are more likely to be swimming along shallow water by the shoreline. Children are most often affected because they swim, wade, and play in the shallow water more than adults. Also, they do not towel dry themselves when leaving the water.

Swimming pools

As long as your pool is well-maintained and chlorinated, there is no risk of swimmer’s itch.


If you have a question, please call us at 519-482-3416 or toll-free 1-877-837-6143. Ask to speak to a public health inspector on the Environmental Health team. You can also email us at beaches@huroncounty.ca.