The itching hour

Biologist Margaret O’Connell was collecting amphibians one hot day, up on the sloughs of the Little Pend Oreille River, when she got an itch.

It was the first spell of 90-degree-plus weather that year. It was lucky she wasn’t swimming, just wading, she said. The red, burning bumps of swimmer’s itch were painful enough on her lower extremities.

“I can remember putting my feet in buckets of ice water and sleeping in the easy chair,” she said.

Swimmer’s itch isn’t dangerous, but it’s very itchy. And it’s in season – in the Northwest, it pops up consistently at some spots and periodically or never in others. The complaints usually start with the first stretch of very hot weather.

Caused by a freshwater parasite that mistakenly tries to make a human its host, swimmer’s itch is a rash of red bumps that may turn into blisters and can last for days.

“I’m going to guess, with the heat starting, now we’re going to start seeing some cases,” said Denis Felton, area manager of Sun Lakes-Dry Falls and Steamboat Rock state parks in Grant County, said last week.

The parks’ lakes have more than 23 miles of freshwater shoreline and host Canada geese – along with snails, waterfowl are key to the parasite’s life cycle – along with human visitors.

“There hasn’t been a summer here in the eight years I’ve been here when we haven’t seen it,” Felton said.

Officials at a couple of other popular swimming spots – Medical Lake and Bear Lake – say they’ve received very few or no complaints about swimmer’s itch in recent years.

Swimmer’s itch doesn’t rank among maladies that must be reported to health districts, said Steve Main, an environmental health specialist at the Spokane Regional Health District.

It’s up to individual parks operators or municipalities to decide whether and how to post warning signs if a problem does arise.

But when warning signs are posted, Main said, it’s usually after at least a few cases have been reported, leaving oblivious swimmers to meanwhile go splashing in.

“You pretty much have to assume that when you’re swimming in a freshwater body, you could have an issue with swimmer’s itch,” Main said.

Felton, at the state parks, said employees there post bright signs warning of the parasite and offering prevention tips.

“But we wait until we’ve seen about three good physical cases where we’ve seen it ourselves,” he said. “The bumps are pretty distinctive.”

Swimmer’s itch isn’t a pollution problem, said Jani Gilbert, a spokeswoman for the Department of Ecology. It’s the result of a naturally occurring parasite’s misguided attempt to find a host to complete its life cycle. It penetrates a human’s skin rather than that of a goose or duck.

“To get rid of it in the lake is to try to eliminate one of the hosts, either ducks or snails,” Gilbert said.

In Seattle parks, the Canada goose population had dropped by 75 percent in 2003, three years after federal agents started rounding up the birds and killing them in portable gas chambers, according to the Seattle Times. The birds were blamed for swimmer’s itch and other problems.

Felton said he’d like to address the problem at the state parks somehow but lacks funding.

Gilbert offered a couple of ways to combat swimmer’s itch: Get people to quit feeding ducks and geese, which encourages them to stick around. And make lake habitats less hospitable for snails by removing riprap from the shoreline, the big rocks or concrete chunks thrown together to prevent erosion.

“Snails love to attach themselves to those boulders,” Gilbert said.

They also grow in size and number near net pens used to raise fish, such as those in Deer Lake, Gilbert said.

For biologist O’Connell, co-director of the Turnbull Laboratory for Ecological Studies and a professor at Eastern Washington University, her encounter amounted to a lesson learned. Now when she goes out scouting wildlife, she goes prepared.

“I’ve been putting waders on every time since,” she said.