LEECH LAKE DIVISION OF RESOURCE MANAGEMENT
-WATER QUALITY PROGRAM-

SWIMMER'S ALERT...
This page will alert the public about any potential dangers we percieve in the area's waterways from water born pathegens.

SWIMMER'S ITCH
Swimmer itch is common during hot summer days in area lakes. It is characterized by small, irritating red welts that appear after swimming that produce severe itching which may last from a few hours to a couple of weeks. If you find that you have these symptoms, you may not choose to swim in that particular lake due to the discomfort you will find.

How to I avoid swimmer itch?
You can avoid infection by vigorously toweling dry immediately after swimming, before water droplets dry on your skin. Application of an oily suntan lotion before entering the water may also help prevent swimmer itch. If welts develop, use calamine lotion to provide relief.

How does the parasite infect me?
Swimmer itch is caused by a parasite that normally infects water birds and mammals. We are affected by swimmer itch when one stage in the life cycle of this parasite, the ceraria, burrows into human skin. Cercariae can tell the difference between their usual host and humans; but, when they are trapped in a droplet of water on the surface of the skin and this small pool begins to evaporate, they respond by burrowing in. They are unable to penetrate underlying barriers of human skin and therefore are unable to maturity in humans. Therefore, this parasite poses no serious threat to humans.

How does the parasite normally live?
Swimmer itch is caused by a parasitic blood fluke. This parasite does not normally affect humans. The irritation is caused during a life stage of a flatworm parasite (Schistosome) which lives as an adult in suitable mammals and birds, such as mice and ducks. The adult worm sheds its eggs via the host’s excretory tract into the water. Here they hatch into a free-swimming stage called a miracidium. The miracidium swim in search of a proper second host animal, a particular type of snail. If a proper snail is found, the miracidium will penetrate into the snail’s tissue and undergo further development. After a three- or four-week development period, another free-swimming stage called a cercaria emerges from the snail in search of the proper primary bird or mammal host.