MARQUETTE - Marquette area beach-goers should be mindful of two common skin ailments when spending time at the lake: sunburn and swimmers itch.
Swimmer's itch, also called cercarial dermatitis, is a skin rash caused by an allergic reaction to microscopic parasites called schistosome. The adult parasites live in the blood of infected animals, like ducks, geese, gulls, swans and aquatic mammals like muskrats and beavers. Their eggs are passed in the animals' feces.
If the eggs come into contact with water, they hatch into larvae. The larvae search for a certain species of aquatic, fresh-water snail. The larvae will infect the snail, which releases a different type of larvae, cercariae, into the water. This cercariae will then search for another host, such as birds or aquatic mammals, in order to continue its life cycle.
Bridget Pliska, 8, of Marquette, goes for a swim in Lake Superior at McCarty's Cove in Marquette in this file photo from the summer of 2009. Bridget is the daughter of Maura and Bob. (Journal file photo by Julia Woehrer)
Though not its preferred host, the parasites will burrow into the skin of humans.
"The rash of swimmer's itch is an allergic reaction to the parasite," said Dr. Jennifer Baldwin, a local dermatologist. "It may develop within one-two hours, or up to 48 hours after exposure to the contaminated water.? The parasite dies within the skin, and does not penetrate further or cause systemic illness."
Baldwin said symptoms include redness and tingling, burning or itching of the skin. Itching may last up to a week.
"The rash of swimmer's itch is an allergic reaction to the parasite."
- Dr. Jennifer Baldwin, dermatologist
"The condition is not dangerous, but may be extremely uncomfortable," Baldwin said. "Treatment consists of control of the itching with anti histamines by mouth and anti-itch cream applied to the skin. The rash generally clears within a week."
Swimmers itch is not contagious
The Centers for Disease Control also recommends corticosteroid cream, anti-itch lotion, applying cool compresses to the affected areas, bathing in Epson salts or baking soda, soaking in colloidal baths or applying baking soda paste to the rash - made by mixing baking soda and water into a paste.
Baldwin said the best way to avoid swimmers itch is to avoid swimming in swampy areas where snails are usually found. People should not feed birds on the beach, as this will attract them to the area and increase the risk of parasites.
"Rinsing off and towelling dry immediately after leaving the water are effective ways to remove the cercariae should you be exposed," Baldwin said.
Sunburn is caused by overexposure to ultraviolet radiation, usually from the sun.
According to the World Health Organization, skin cancer is the most common type of cancer in humans and in white populations and 80-90 percent of cases are due to exposure to sunlight.
Baldwin said the the American Academy of Dermatology recommends using a sunscreen with broad spectrum UVA and UVB protection with an SPF of at least 30.?
"Sunscreen should be reapplied every two-four hours during prolonged exposure to the sun, and after swimming. A waterproof, sweat-proof type is ideal," she said.?
Sunscreen, while a common defense against sunburn, does not completely cancel out the effects of UV-light.
Scientific research by the International Agency for Research on Cancer of the World Health Organization concluded that use of sunscreen probably prevents squamous cell carcinoma, the most common type of skin cancer, but its effect on malignant melanoma is more complex.
Several studies have shown a greater risk of melanoma in users of sunscreens than in non-users. Scientists guessed this might be due to users of sunscreen being out in the sun more often than they would regularly.
So the protective effect of sunscreens can be outweighed by overexposure to the sun, the group concluded. Baldwin suggested wearing a hat or sun protective clothing, avoiding overexposure during midday and seeking shade when possible.
"Using a 'base tan' as sun protection is not recommended, as a tan actually is a manifestation of damage to the skin, which should be avoided," Baldwin said.
Christopher Diem can be reached at 906-228-2500, ext. 242. His e-mail address is firstname.lastname@example.org.