Swimmer's Itch Information

Swimmer's itch is a natural phenomenon that occurs in many water bodies in Michigan. It is a temporary skin irritation caused by an invisible parasite found in lakes and ponds. The skin irritation appears as small itchy welts resembling a rash or mosquito bites. The welts are caused by a tiny parasitic organism which normally lives in the blood of waterfowl. 

The parasite's eggs are passed out of the bird and develop into larvae that seek out snails. Once they mature, they enter the water again to seek out birds, but sometimes select a human by mistake. Humans are not suitable hosts for the parasite, so it dies and is dissolved. Our body reacts to the intrusion by treating the organism as a mild allergy and produces histamines that can cause a red itchy welt. These itchy bumps are no more serious than an insect bite and can be treated with anti-itch creams.

Misconceptions About Swimmer's Itch

Swimmer's itch is not:

  • Caused by poor water quality
  • Contagious
  • Dangerous to humans

Swimmer's Itch & You

Incidences of swimmer's itch are most common in late June and mid-July, especially after heavy winds. Only 30% to 40% of the population is sensitive to swimmer's itch, and very few of those will ever develop welts. Since swimmer's itch can be reintroduced to the water through goose droppings, please do not feed or attract geese while near lakes or ponds!

To Reduce the Chance of Getting Swimmer's Itch

  • Apply waterproof sunscreen or baby oil to help prevent swimmer's itch organisms from entering the skin.
  • Thoroughly and briskly towel-off or shower as soon as you leave the water to help prevent swimmer's itch organisms from entering the skin.
  • Change out of your wet bathing suit as soon as possible after exiting the water.
  • Keep anti-itch creams handy if your family is prone to allergies or if welts occur.

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