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Definition
Swimmers' itch, also known as cercarial dermatitis, is an itchy rash caused by certain parasites that normally live on waterfowl and freshwater snails. On warm, sunny days — especially in calm freshwater lakes or ponds — these parasites can be released into the water. During a swim, these parasites might burrow into your skin. They soon die and cause an itchy rash.
Swimmers' itch has been reported in countries throughout the world, leading to various nicknames with a national or regional twist. Swimmers off the coast of New Jersey may call it "duckworms." People in Asian countries might use the term "rice paddy itch."
Although uncomfortable, swimmers' itch is usually short-lived. The rash typically clears up on its own within a few days. In the meantime, you can control itching with over-the-counter or prescription medications.
Symptoms
Swimmers' itch is characterized by itchy, red, raised areas on your skin. Swimmers' itch usually affects only exposed skin — skin not covered by swimsuits, wet suits or waders. It doesn't typically affect the face, palms of the hands or soles of the feet. The rash may appear up to 48 hours after swimming in infested water. If you're exposed to the same parasites again, the rash might become more severe.
Causes
Swimmers' itch is caused by parasites that migrate from snails to ducks, geese, gulls, swans, muskrats and beavers. The parasites then return to water through infected feces and eggs.
Swimmers' itch isn't contagious. You don't need to worry about "catching" swimmers' itch from someone who has the itchy rash.
Risk factors
Your risk of swimmers' itch depends on a number of environmental factors:
- Air and water temperatures that are warm enough for snails to reproduce and grow, such as in the late summer months in many parts of the world
- The return of migrating birds infected with parasites
- Bodies of water that contain parasites, especially along shorelines and in shallow areas
The more time you spend in infested water, the higher your risk of swimmers' itch. Children may have the highest risk since they tend to play in shallow water and are less likely to dry off with a towel.
Some people are more sensitive to swimmers' itch than are others. However, your sensitivity can increase each time you're exposed to the parasites that cause swimmers' itch.
When to seek medical advice
Consult your doctor if you have a rash after swimming that lasts more than three days. You might be referred to a doctor who specializes in skin conditions (dermatologist).
Tests and diagnosis
Diagnosing swimmers' itch can be a challenge. A swimmers' itch rash can resemble poison ivy, chickenpox, dermatitis, impetigo or even herpes. Blood and skin tests don't detect the parasites that cause swimmers' itch. Be sure to tell the doctor if your symptoms appeared after swimming or if others developed a similar rash after swimming in the same place.
Complications
Swimmers' itch rarely leads to complications. However, infection is possible if you scratch the rash too harshly.
Treatments and drugs
Swimmers' itch typically clears up on its own within a few days, though in some cases the rash can last up to a week. In the meantime, you can control itching with over-the-counter antihistamines or anti-itch creams, such as those that contain calamine lotion. If the itching is severe, your doctor may recommend a prescription medication.
Prevention
To reduce the risk of swimmers' itch:
- Choose swimming spots carefully. Avoid swimming in areas where swimmers' itch is a known problem or signs warn of possible contamination. Also avoid swimming or wading in marshy areas where snails are commonly found.
- Avoid the shoreline. If you're a strong swimmer, head to deeper water for your swim.
- Rinse after swimming. Rinse exposed skin with fresh water immediately after leaving the water, then vigorously dry your skin with a towel. Launder your swimsuits often. You might even alternate between several different swimsuits.
- Skip the bread crumbs. Don't feed birds on docks or near swimming areas.
- Take care of your pool. If you have a pool, keep it well maintained and chlorinated.
Lifestyle and home remedies
As much as you're tempted, don't scratch! In addition to a cream or medication to soothe swimmers' itch, it might help to:
- Cover affected areas with a clean, wet washcloth.
- Soak in a bath sprinkled with Epsom salts, baking soda or oatmeal.
- Stir water into baking soda until it makes a paste and then apply it to the affected areas.
Remember, if the itching is intense, ask your doctor about prescription medication to ease your symptoms.
Last Updated: 02/01/2007
