Do you suffer from red spots on the skin that itch and burn after swimming in stagnant freshwater? You may be suffering from swimmer’s itch. Swimmer’s itch is caused by the larvae of a worm species found in ducks penetrating a small part of the human skin, causing an allergic reaction. Swimmer’s itch normally goes away on its own and does not require treatment. Cool compresses or a menthol gel can help relieve the itching.
- What is swimmer’s itch?
- How do you get infected?
- Larvae of a flatworm
- Cercariae
- How can you prevent infection?
- Symptoms of swimmer’s itch: red spots after swimming
- Phenomena
- Notify GGD
- How can swimmer’s itch be treated?
- Self-care
- Relieve itching
What is swimmer’s itch?
Swimmer’s itch is also called cercarial dermatitis, schistosoma dermatitis or swimmer’s itch . Swimmer’s itch is an allergic reaction due to the larvae of the flatworm Trichobilharzia, a species of worm found in ducks, penetrating a small part of the human skin. The parasitic worm Trichobilharzia occurs in water birds, such as ducks.
How do you get infected?
Larvae of a flatworm
The worm Trichobilharzia is a schistosome, a genus of parasitic worms. The worm lives in the blood vessels of vertebrates and mainly infects duck and geese species. The eggs of the worm end up in the water through the bird droppings, where a larva (miracidium) hatches from the egg. The eggs of these worms develop via an intermediate host, often aquatic snails of the genus Lymnea or Radix, into a new type of larvae (a cercaria). These snails live in fresh water, especially in not so deep, stagnant or rather slowly flowing water, such as a recreational lake of fresh natural water. These cercariae are secreted again and in turn go in search of water birds, where they crawl in through the legs and thus end up in the vascular system of the host. There the whole cycle starts all over again.
Cercariae
So the cercariae normally infect waterfowl, but they can also accidentally penetrate human skin. Unlike waterfowl, they remain stuck in the skin of humans; they cannot move further into the blood vessels. Their presence in the skin causes an allergic reaction with all the associated complaints (see below). As soon as the weather becomes summery and recreational users start swimming in surface water, often at the end of spring or the beginning of summer, the first reports of swimmer’s itch occur. A fortunate coincidence is that the larvae die immediately once they are present in a human’s skin. Swimmer’s itch can mainly be contracted during good weather, when many larvae or cercariae are present in the water.
How can you prevent infection?
You cannot see the larvae with the naked eye. In outdoor water that is classified as bathing water, the presence of the culprit is actively monitored during the summer period. If larvae are found, warning signs are placed along the side of the recreational lake. Keep in mind that not all places where you can swim are checked. The province will only check at official swimming places. The risk is mainly present in recreational lakes where both ducks and snails are found. This often concerns fairly shallow, stagnant or slowly moving water. For current information, please visit www.zwemwater.nl. It is also advisable to shower immediately after swimming and then dry the skin very thoroughly by scrubbing the skin.
Symptoms of swimmer’s itch: red spots after swimming
Phenomena
When a larvae penetrates the skin of a human, it dies. You can often experience a stinging, itchy feeling when the larvae penetrate the skin. This sensation can last for about 1 hour, after which, as a result of an immune reaction, itchy, red bumps appear on the skin, which can feel like burning. Suppose you are infected again later. In that case, the symptoms will be more severe because the larvae will be killed sooner by the skin reaction. This may be accompanied by severe itching and red spots on the skin that become bumps. The rash may coalesce into larger patches of slightly swollen red skin. Blisters can also form. You may also experience headaches, nausea and fever. If you come into contact with larvae more often, the complaints may last longer (i.e. one to several weeks). However, the complaints vary from person to person. Some people get an itchy rash right away, while others take two days for the rash to appear. Avoid scratching, as this can lead to skin infections.
Notify GGD
If you have health complaints after swimming in open water, it is important to report this to the infectious disease control department of the GGD.
How can swimmer’s itch be treated?
Self-care
Swimmer’s itch normally heals on its own within about a week and therefore does not require treatment. If you have serious complaints, contact your doctor, for example if scratching has caused skin infections or if the rash is very persistent and/or accompanied by fever. The following advice can help to alleviate the complaints:
- Place cool compresses on the affected areas.
- Apply menthol cream or gel to the bumps.
- A little vinegar on the itchy areas can help.
Relieve itching
It is possible that in case of severe itching, an oral antihistamine can help to relieve the itching, or short-term use of a corticosteroid cream. Ask your doctor for advice.
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