Swimmer’s itch makes its annual return to Seattle area lakes

An unpleasant side effect of Seattle’s summer seems to be rearing its ugly head again, as complaints of swimmer’s itch have begun surfacing.

One of our colleagues – who shall remain nameless – started complaining of an itchy rash this week after taking a swim in Green Lake. While she hasn’t been to the doctor, it’s got all the tell tale signs of the condition.

“It looks like reddish pimples or blisters, and can appear within minutes or even days after swimming or wading in infested water,” says Teri Barclay, a health and environmental investigator with Public Health – Seattle & King County.

The itchy rash is caused by a parasite in lake water, Barclay says. If water contaminated with parasites dries on a swimmer’s skin, the microscopic bugs can burrow into the skin. Although the rash can be very uncomfortable, it is not serious and affects only the skin, not the rest of the body.

The parasite that causes swimmer’s itch is deposited into lakes through goose and duck droppings. The organisms then move into snails where they mature, eventually coming out to re-infect more waterfowl. Occasionally, they infect people as well.

“It is an allergic reaction,” Barclay says.

The rash usually goes away on its own. But in the meantime, you can control itching with over-the-counter antihistamines or anti-itch creams, such as those that contain calamine lotion. If the itching is severe, your doctor may recommend a prescription medication.

Barclay says lakes like Green Lake, that have shallow water, birds and marshy areas, are most prone to swimmer’s itch. But there are some simple steps to take to minimize your risk:

-Liberally apply a waterproof sunscreen prior to swimming. There is evidence that this may provide some protection.

-Briskly dry off with a towel as soon as you come out of the water, including the skin under the swimsuit.

-Shower immediately if facilities are available.

-Stay fully immersed in the water. Wading creates the highest risk for swimmer’s itch.

-Do not feed ducks and geese. This may attract more of these birds to the area and increase contamination of the water and shoreline.

-Avoid swimming in marshy areas where snails are commonly found.

Barclay says if the department gets a number of reports, it will contact local jurisdictions to post warnings. But so far, there haven’t been enough reports to justify taking any specific action.

In the past, swimmer’s itch has been reported at a number of beaches across the area including Seward Park, Magnuson Park, Matthews Beach Park and Juanita Beach Park.