Jumping into a lake is a rite of passage during a Michigan summer. But if you leave the water with itchy skin, you may have a case of swimmer’s itch. You’re more likely to develop a case of swimmer’s itch after visiting an inland lake versus one of the Great Lakes. While swimmer’s itch is not contagious or dangerous – and is not caused by poor water quality – it can cause an annoying rash that sometimes lasts up to a week.
What causes swimmer’s itch?
Swimmer’s itch is a skin rash caused by an allergic reaction to parasites that burrow into the skin, according to the Centers for Disease Control and Prevention (CDC). The parasites have a complex lifecycle that starts by infecting animals including ducks, geese, gulls and swans, as well as mammals including muskrats and raccoons. The parasites make eggs, which can wash into rivers, lakes and oceans. In the water, the eggs hatch and swim as microscopic larvae in search of their next host. The larvae are searching for a specific type of snail. Once they find the snail and infect it, another type of very small larvae is released into the water. This form of the parasite is searching for a bird or animal to infect so it can begin its life cycle again. However, if this form of the parasite finds a human, it attempts to infect it – burrowing into the skin and causing the rash known as swimmer’s itch. The parasitic larvae cannot survive with a human host, and they soon die.
Signs and symptoms of swimmer’s itch
Symptoms of swimmer’s itch include:
- Small reddish pimples
- Small blisters
- Tingling, burning or itching of the skin
Symptoms can develop within minutes to days after swimming in contaminated water, beginning with tingling or itching. Within 12 hours, pimples may appear that can then develop into blisters.
Treatment for swimmer’s itch
The CDC advises itching can last up to a week, but it will go away on its own. Most cases can be managed at home. Cold compresses, corticosteroid creams or baths with Epsom salts, baking soda or colloidal oatmeal may help soothe the skin. Baking soda mixed with water into a paste may also help relieve the symptoms.
How can I prevent swimmer’s itch?
When swimming in an outdoor lake, take the following precautions:
- Check with local public health officials to make sure there are no warnings in place.
- Apply waterproof sunscreen or baby oil to the skin before swimming to create a waterproof barrier on the skin.
- Dry off with a towel immediately after swimming.
- Don’t encourage ducks or geese to gather at lakes or ponds by feeding them.
- Pay attention to the wind and water conditions: the snails that host the parasites tend to thrive in warmer waters. Don’t swim or wade in marshy areas. Winds pushing the water towards the beach can concentrate the snails and their parasites near the shore. Warmer water along the shoreline coupled with winds coming into the beach could potentially push more parasites into swimming areas. The parasites that cause swimmer’s itch are typically found in smaller lakes; the Great Lakes including Lake Michigan, Lake Huron and Lake Superior are often too windy and wavy to sustain the snails and their parasites.
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