Parasite under the skin: what you need to know about cercaria in bathing lakes

parasite under the skin
What you need to know about cercaria in bathing lakes

When the weather is nice, many people say: off to the lake! But when the water temperatures rise, not only swimmers can be found in the natural waters, but also microscopic flukes that burrow into our skin. We’re talking about cercaria. The parasites cause an itchy skin rash in humans, also known as swimmer’s rash. How dangerous are cercaria and can you protect yourself from them?

Cercaria are According to the State Office for Health and Food Safety (LGL), it is a larval stage of certain flukes that swim freely in the water. The parasites actually infect waterfowl such as ducks, geese or swans, burrow into their skin and organs, develop in their bodies and their eggs are excreted in the birds’ droppings. In the search for a suitable definitive host, the parasites mistakenly burrow into human skin.

Are cercaria dangerous to humans?

Cercaria infestation can be deadly for waterfowl. However, it is harmless to humans. According to LGL, cercariae are killed by the human immune system upon initial contact. In the development cycle of flukes, humans are what are known as false hosts, in which the parasite can neither survive nor develop for a long time.

However, an infestation by cercaria does not leave people unnoticed. It can cause an itchy rash in the form of millimeter-sized, red patches. As a rule, however, these heal after ten to 20 days. Caution: If the areas are scratched, they can ignite. Anti-inflammatory and anti-itch ointments, gels or lotions help against itching.

How swimmers can protect themselves from cercaria

The larvae cannot be seen with the naked eye. You can still protect yourself. Cercaria prefer shallow, standing water and water temperatures above 20 degrees. If you want to prevent an infestation, you should avoid flat shore zones – especially if aquatic plants grow there. It is best to jump directly into deep water – for example from the jetty or boat. It is also important to avoid areas with water snails and waterfowl. There are often warnings at lakes that have already had cases of swimmer’s dermatitis. The LGL also advises avoiding bathing in the early hours of the morning.

Sunscreen can not only help against UV radiation, but also against cercaria – preferably a waterproof lotion. If possible, an anti-jellyfish lotion can also be used. It is also helpful to change your bathing suit immediately after swimming and rub your body vigorously with a towel.

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