VERNAL — Low water levels, high temperatures and an abundance of aquatic snails have combined this year to cause an outbreak of "swimmer's itch" in the reservoir at Steinaker State Park.

"I've worked here for 16 years and this is the second time I know that we've had it," said park manager Mike Murray.

The park has recorded "seven to 10" cases of cercarial dermatitis — the scientific term for the skin condition commonly known as swimmer's itch — so far this summer, Murray said. It's the first time since 1999 that a case has been reported, he said.

"Usually it's kids that get it," Murray said, noting that children tend to spend more time playing in the warmer water near the shore.

"That's when these larvae try to attach to you," he said.

Swimmer's itch is caused when the free-swimming larvae of a waterborne parasite cast off by aquatic snails mistake humans for their intended host species — ducks.   

"It just comes into your skin, and once it's in there, you're an accidental host and the (larva) dies and it causes a little bug bite," said Dr. John Blake, a dermatologist at Uintah Basin Medical Center in Roosevelt.

"It's really more of a nuisance problem," Blake said. "You can't give it to anybody.

"Even without treatment, it's going to be a limited time that you'll have the problem," he added.

A typical case of swimmer's itch causes discomfort for two or three days. It can be treated with topical ointments and over-the-counter antihistamines, Blake said. More severe cases, however, can last longer and may mask a more serious problem.

"In those cases, it's always good to see a doctor and get a proper diagnosis," Blake said.

Steinaker isn't the only state park in Utah with reports of swimmer's itch this summer. Cases have also been reported at Sand Hollow Reservoir in Hurricane and at Wide Hollow Reservoir near Escalante, according to Utah State Parks spokeswoman Deena Loyola.

The parasite is present in lakes and reservoirs around the country, but no single state agency in Utah tracks the occurrence of swimmer's itch.

Not everyone who comes in contact with the parasites will be affected, according to research, because the blemishes they cause are the result of an allergic reaction.

"A lot of people aren't susceptible to it," Murray said.

Still, officials at state parks where the parasite has been detected are handing out pamphlets to visitors about the potential for problems and trying to spread the word online

At least one group isn't too upset about the parasite's presence. Boaters say word that swimmer's itch is present in a body of water often keeps many people away, and leaves places like Steinaker wide open for them to enjoy.

"We're just flaming red with all sorts of rashes and stuff, so don't come here," said Kent Mansfield of Vernal as he prepared to load up his boat after a day on the water.

"But seriously," Mansfield said with a chuckle. "We spent most of our time out in the middle of the lake where it's really not an issue, so I'm not all the worried."

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