#Pyramid lake swimmers itch series#

Gaining the freedom of open water, they locate snails to infect, thereby completing the cycle. Afterwards, they migrate to the digestive tract where they produce eggs ready to be shed into the water with the duck’s feces. Finding one, they bore through its skin, somehow finding one another in the circulatory system to mate (I believe the animals are bisexual). You could see them with your eyes if you cared to look.Īfter leaving the snails, apparently tired of the pace of life there, they swim around looking for a secondary host, frequently diving ducks such as the Common Merganser. Compared to other such water creatures, they weren’t that small. Many years ago, at the University of Michigan Biological Station, I remember seeing them emerge from snails confined to a watchglass under a low-power microscope.

These cercariae are neither bacteria nor viruses, but a member of the flatworm phylum. The cause of the itch has been known for many years: a tiny parasite inhabits snails of the lake, shedding them into the water on warm summer days. This media comes from the Centers for Disease Control and Prevention’s Public Health Image Library (PHIL), with identification number #8556. Barr Library Librarians Melissa Rethlefsen and Marie Jones, Prof. Image made available on Wikimedia Commons by the CDC/ Minnesota Department of Health, R.N. The sample itself was taken from Lake Owasso, Minnesota. This material was obtained from Professor William A. The purpose of the images and the accompanying training was focused on protecting potable water supplies from contaminants including toxins, and pathogenic organisms, such as the parasite pictured here.

#Pyramid lake swimmers itch series#

This was one of a series of instructional images used by the Minnesota Board of Health to train its state public health workers. This historic 1942 photomicrograph revealed some of the morphologic details displayed by a schistosomal cercaria, which is the larval stage of a parasite that causes “swimmer’s itch”, and was magnified approximately 150x.

In a few days it disappears on its own, anyway.

Little can be done to alleviate the itching-the old remedy of baking soda is probably as good as any. Children are especially affected as itchy red bumps appear on legs and torso, soon after swimming. Swimmer’s Itch plagues many Michigan lakes.