Itching for answers

PABLO— It is every child’s worst summer time nightmare; small, itchy bumps cropping up on their bodies after a day swimming on the lake. The virulent allergic reaction, caused by a parasite native to Flathead Lake, has been reported in considerably large numbers this year, prompting local scientific research groups to look more into the parasite’s life cycle.

“One explanation for the amount of swimmer’s itch in the lake this year is the record temperature the lake has reached,” commented Flathead Lake Biological Station research scientist Jim Craft. “The parasite comes from a snail, and the heat of the lake this year creates more algae, which those snails feed on. The warmer temperatures could also speed up the life cycle of the parasite after they leave the snail, which would increase the rate of parasites attempting to enter human hosts.”

In 1999, Flathead Lake Biological Station (FLBS) published a handout about the basic lifecycle of swimmer’s itch. The parasite develops inside snails, and then is released at its “young-adult” stage in search of its next host — typically a duck or a goose. The parasite develops into an adult inside the waterfowl and lays its eggs, which are then excreted by the bird.

“In 2003, a young biologist named Andrea Grahan did a study for us about swimmer’s itch. She looked at five different parks and tested both snails and ducks. She found that roughly 60-80 percent of ducks are infected with the parasite, but less than three percent of snails are,” said Craft.

Humans interrupt the life cycle when the parasites are seeking their second host. The parasites try to burrow into human skin, but the human immune system kills the trespasser and creates itchy red bumps.

“We have very little data to work with, but it doesn’t seem now that there is a lot we can do to exterminate, or effectively test for, the parasites before they enter the human body,” commented Craft.

It is such a test that researchers at Salish-Kootenai College have been trying to develop for the past two summers. The project, led by SKC faculty member in the department of life sciences, Libby Rutledge, has made impressive strides and is looking forward to more in the next few summers.

“I began this project last year with two students who received grants out of the National Science Foundation in Minnesota to study with us,” said Rutledge. “We didn’t find the parasite last year because we didn’t know what we were looking for, but this year we were finally able to identify it.”

Rutledge went on to say that her newest research partner, SKC biology professor Kirwin Werner, was instrumental with much of the progress that was made this year.

“Kirwin was very important this year for helping us know what to look for because he specializes in parasites that find hosts in amphibians and reptiles. Several different types of parasites can occupy a snail at a time, and he helped us find the right ones for our research,” commented Rutledge.

According to Werner, the search for the parasite made the ultimate goal more complicated.

“Our focus this summer was to find the parasite and the type of snail that the parasite attacks. We found that about four or five types of parasites can cause swimmer’s itch, which makes developing a test more complicated,” said Werner.

A significant amount of research still needs to be done before the SKC research team can get to the point of developing a test.

“Right now, we want to find a parasite at the beginning of its life cycle — right when it comes out of the duck. If we can find it then, we could infect a snail and study its life cycle over the winter,” said Rutledge.

Eventually, the project goal will be to develop a water test for the parasite.

“Right now the only way to know if the parasite is inhabiting a certain area is to test individual snails, which is time-consuming,” said Werner. “If we could find a way to test the water, it would become much simpler.”

The main concern remains that swimmer’s itch increases in severity in each case for an individual person, and that it is difficult to prevent.

“Putting lotion on before swimming and towel drying immediately after can help to prevent the infection, but at this point there is no easy solution,” commented Rutledge. “In the past some people have tried putting copper sulfate in the water to kill the parasite, but that also kills other native species.”

The research team at SKC plans to continue its efforts to subdue the annual swimmer’s itch problem each summer that students choose to study with them.

“We want to study things that are local and relevant,” said Rutledge. “And swimmer’s itch hasn’t been studied here in depth before. It’s a big ecological question and we’ll keep going.”