The Provincie Groningen and the GGD have issued a warning against swimming in the Hoornseplas. Multiple complaints of rashes and an itchy, burning feeling in the skin led to an investigation of the cause. 

Apparently, snail larvae (invisible to the naked eye) are present in the water, trying to find water fowl who are their natural hosts. When the larvae come in contact with human skin, the larvae try to burrow into the skin and eventually die, leaving the swimmer with an allergic reaction.

Although the skin rash should disappear after a few days, the reaction can also include a headache and fever. If a person is exposed to the larvae multiple times, the reaction can become worse.

If anyone has experienced these symptoms after swimming in open water, it is advised to contact your family doctor.