Identifying, treating, and preventing swimmer's itch
The bottom line
Swimmer's itch occurs when your body has an allergic reaction to parasite larvae found in swimming water. While the rash maybe uncomfortable and is often very itchy, it usually resolves with simple home treatment.
Prevention Tips
Do not feed birds in areas where people swim.
Avoid swimming in marshy or shallow waters whenever possible, as there are more snails in these areas.
Avoid swimming in areas where posted signs warn that swimmer’s itch is a problem.
Prolonged time in water is a risk factor for swimmer’s itch and can result in more severe symptoms.
Towel dry and shower immediately after leaving the water, and shower as soon as possible.
Apply waterproof sunscreen, as this might protect the skin from larvae that cause swimmer’s itch.
This Really Happened
A 41-year-old woman went swimming in a lake where there was a lot of vegetation present near the water surface. The next day, she developed an itchy rash on her face and shoulders. Her skin felt hot, and she noticed the symptoms were worse in the morning. She went to her primary care doctor, who recommended the use of oral antihistamines and moisturizing lotion. She also saw a dermatologist who performed a skin biopsy that revealed the presence of cercariae in her skin. This confirmed the diagnosis of swimmer’s itch. She was treated with prescription antihistamines and topical steroid cream. The rash completely resolved within 2 weeks (from Tremaine et al., 2009).
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What is swimmers’ itch?
Swimmer’s itch is a water-borne parasitic disease, and the normal life cycle of the disease-causing parasite involves different animals. Several species of birds (e.g., geese, ducks, gulls) and mammals (e.g., beavers, raccoons) that live near water can be infected with parasites. The adult parasites produce eggs, which are passed in the feces of these animals. If the parasite eggs are released into or near water, they can hatch into larvae (immature forms), which can then infect fresh-water snails. The snails release a different larval form of the parasite called cercariae. The cercariae can be encountered by swimmers, particularly in shallow and marshy areas, although they are too small to see. The cercariae can painlessly burrow into human skin, but they are not able to survive there. They die, and their remains in human skin can cause the characteristic itchy rash (cercarial dermatitis).
What are the symptoms of swimmers’ itch?
Within a few minutes to a couple of days after swimming in contaminated water, a rash can develop. The rash can appear similar to pimples, chickenpox, or blisters and is often red, itchy, or burning in nature. The rash typically involves areas of the body that were exposed to contaminated water, with areas of skin covered by bathing suits usually being spared. This helps to differentiate swimmer’s itch from saltwater seabathers’ eruption, which primarily affects the skin under swimsuits. While the swimmers’ itch rash is uncomfortable, it is generally self-limited and not dangerous. Because it is an allergic reaction and not a true infection, swimmer’s itch is not contagious. Severe symptoms, including fevers, diarrhea, and nausea, occur rarely.
How do you treat swimmers’ itch?
Most cases of swimmer’s itch can be easily treated at home. If you suspect swimmer’s itch, you should take a shower if you have not already done so after getting out of the water. Drying your skin with a towel instead of air drying might help remove some of the cercariae from the skin. Cool compresses and soaking in Epsom salts or oatmeal baths can soothe the rash. Baking soda baths and pastes can be helpful as well. Topical steroids, such as hydrocortisone cream, and antihistamines, such as diphenhydramine (Benadryl®), can be used to treat itching. More severe cases can require treatment with prescription medications. Avoid excessive scratching of the itchy areas because this can lead to a skin infection. Most cases of swimmer’s itch will resolve within 1 to 2 weeks with simple home treatment. If symptoms do not resolve or if the rash appears to be getting infected, seek medical attention.
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