Swimmer’s dermatitis

What is it about ?

Swimmer’s or swimmer’s dermatitis is a skin condition caused by tapeworm larvae (trematodes) entering the skin. These are parasites that a number of aquatic birds, such as ducks, carry. Via the feces of these animals, the eggs of the worms end up in the water, where they develop into larvae. They then enter some water snails and continue to grow before they end up in the water again.

They can penetrate the skin of humans if they swim in contaminated water. Usually, the person does not have any symptoms at first contact. However, through its defense mechanism, the body is indeed sensitive to larvae, so that in the event of subsequent contact, a defense reaction will be triggered and cause the symptoms.

What is its frequency?

These infections are relatively rare because it takes both waterfowl and water snails to support the worm’s life cycle.

How to recognize it?

Red spots and blisters (papules) appear on the skin. If the person is just wading in the water, symptoms will mostly affect the feet, but swimmers can have them all over their body.
The rash occurs within a day of contact. Then it gradually weakens and disappears after about a week.

How is the diagnosis made?

The doctor will suspect swimmer’s dermatitis if a rash appears after swimming in open water. Sometimes a larva is visible under a microscope in one of the blisters. It is not necessary to take any specialized exams.

What can you do ?

Avoid swimming in open water where ducks and geese wade. If you did swim in it anyway, dry your skin vigorously with a towel to remove most of the larvae.

What can your doctor do?

Swimmer’s dermatitis does not require treatment. It heals spontaneously in a few days, up to 3 weeks.

If necessary, you can use an itchy cream or oral antihistamine. A low potency cortisone cream can also be used temporarily.

Want to know more?

• Corticosteroids for the skin (low potency preparations) – CBIP – Belgian Center for Pharmacotherapeutic Information
• Antihistamines – CBIP – Belgian Center for Pharmacotherapeutic Information

Source

Foreign clinical practice guide ‘Cercarial dermatitis’ (2000), updated on 02/28/2017 and adapted to the Belgian context on 08/30/2019 – ebpracticenet