ST. GEORGE — A petition to remove the parasite responsible for swimmer’s itch from Sand Hollow State Park has been circulating through social media, prompting St. George News to determine if an eradication program is possible and if so, what that operation would look like.
The Change.org petition to remove swimmer’s itch from Sand Hollow State Park was started by Nicolas Wagner on June 5, based on claims that the water in Sand Hollow Reservoir is “overwhelmed with a parasite known as Cercarial Dermatitis, aka Swimmer’s Itch.” The petition states that the water should be “treated for Swimmer’s Itch immediately.”
The Centers for Disease Control describes swimmer’s itch, or “cercaria,” as a skin rash caused by an allergic reaction to microscopic parasites carried by waterfowl, semi-aquatic mammals and snails.
The petition lists Utah State Parks and Recreation as the agency that should be responsible for the cleanup, but the department’s public information officer, Devan Chavez, told St. George News it is not possible to rid the water of swimmer’s itch “immediately,” adding that it doesn’t appear to be possible at all.
“We haven’t been made aware of any program that will remove swimmer’s itch from Sand Hollow or any other body of water in Utah,” Chavez said. “We have researched the issue but have yet to find anything that would be effective.”
Even if a solution were available, he said, there are multiple agencies that would need to “come to the table” to conduct impact studies on wildlife, agriculture and the food chain.
“But again,” he said, “we have not found a program that has any level of effectiveness.”
Why can’t we beat the itch?
The fundamental issues involved with implementing an eradication program have to do with the life cycle of the parasite, the effect a chemical additive may have on the environment and logistics.
First, the life cycle of the parasite that causes swimmer’s itch is a three-stage cycle, according to the Centers for Disease Control.
The larvae go through various stages of development, similar to a butterfly, starting with the adult flatworm that lives in the blood of infected birds. The female flatworm lays eggs that are released through the birds’ feces.
Once in the water, the eggs hatch and swim to the surface to optimally find a snail. If successful, the larvae enter the snail and continue to develop, producing thousands of new parasites that are then released into the water where they begin the search for a bird again, completing the cycle.
However, if the larvae find a human first, they burrow into the skin of the swimmer and die off, since humans aren’t appropriate hosts. This is what causes the “itch,” a rash that appears as red, bite-like welts within several hours of leaving the water.
To address the problem, different eradication attempts have been tested in various states, including treating the snail population with an insecticide such as copper sulfate, which can be added to the water in early June and has had some effect in reducing the number of snails.
However, according to research conducted in Michigan, chemical treatments are only effective on the snail population present at the time of treatment, with no residual protection going forward. These chemicals also kill other plants and animals and may contaminate sediments, which can have long-range consequences that are still being studied.
The second issue relates to water, which is critical to the life cycle of the parasite.
Any chemical added to Sand Hollow to eradicate the snail population could have far reaching effects on the water supply, said park ranger and assistant manager Stephen Studebaker.
“Anything that affects Sand Hollow can also have an affect on Quail Creek and the Virgin River, because the water flows between all three,” Studebaker said. “We have 3,500 acre feet of surface water at Sand Hollow, which is a huge area.”
Studebaker added that the water does not belong to the park; it is managed by the Washington County Conservancy District, an agency that diverts and stores more than 33 trillion gallons of surface water annually that is used to supply residents throughout the county.
Sand Hollow Reservoir is the largest of five reservoirs managed by the agency.
Water from the Virgin River is diverted into the Quail Creek Reservoir, as well as Sand Hollow, a reservoir that sits on a natural sandstone aquifer that stores and holds 17 billion gallons of water, Washington County Conservancy District’s general manager Ronald Thompson said.
That water is used to regulate levels between the two reservoirs before it is piped over to the Quail Creek Water Treatment Plant for processing and becomes part of the county’s water system.
Thompson told St. George News that copper sulfate is “occasionally” used at the water treatment facility to remove nonbeneficial algae during the treatment process but said it isn’t something they would put directly into the water at Sand Hollow to remove the snail population.
“We certainly wouldn’t treat the whole lake with copper sulfate because it would kill off the beneficial algae and would have little effect, if any, on the snail population,” he said, adding that the water ultimately serves as the drinking water for more than 150,000 residents.
More importantly, the bird population would have to be treated along with the snails, since both are necessary hosts for larvae development. This process involves capturing and administering a de-worming medication similar to the type used for cats and dogs.
However, Thompson said, the bird population surrounding Sand Hollow is migratory, which means that even if it were possible to treat every bird, the population changes from one day to the next.
“With today’s technology, I just don’t see any way to successfully treat both the snail and bird population,” he said. “It’s just not possible.”
Utah is not alone in the battle against swimmer’s itch. Thirty states across the country have reported cases of the parasite, along with Canada and Europe, the CDC says.
One state that has conducted extensive testing and research on swimmer’s itch is Wisconsin, with its 15,000 lakes along thousands of miles of coastline.
Even so, Wisconsin has yet to find a viable option to control or eradicate swimmer’s itch, according to the Wisconsin Department of Natural Resources.
“There is no effective way to eliminate swimmer’s itch, and any attempts at control are ineffective because cercariae are capable of swimming or drifting long distances from non-treated areas,” the agency’s website said.
The good news?
Without an available option to eradicate the parasite, educating the visiting public is the focus at Sand Hollow State Park, Studebaker said, including posting signs when the parasite is active, one of which is located at the park’s entrance.
“We want the public to be informed, which allows them to take precautions and protect themselves and their families,” Studebaker said, “even if that means turning around and leaving.”
Studebaker said that so far this season, the actual number of cases compared to visitor numbers is “marginal.”
In addition, not everyone will be affected. Less than 7 percent of the population is affected by swimmer’s itch, and of those who are, a majority build an antibody after one reaction and do not experience symptoms again. Small children playing in shallow water are most susceptible, as they cycle between being wet and dry throughout the day, which increases the risk of being infected as the larvae tend to burrow once the swimmer leaves the water.
The level of discomfort varies with the person’s sensitivity and the extent of infestation, said David Heaton, Southwest Utah Public Health spokesperson, adding that while swimmer’s itch is neither dangerous nor contagious, it can be painful and very uncomfortable.
“It’s one of those things that is a nuisance and uncomfortable but has no lasting effects,” Heaton said.
“Anytime there is heat, a large body of water with a lot of standing water, and snails and birds around, then we get a lesson on interacting with nature,” he added.
There are steps park visitors can take to minimize the risk of exposure, Studebaker said. The first is to avoid areas where plants or vegetation are growing and swim away from the shore whenever possible.
Areas where winds and wave currents tend to carry algae into the shallow water should also be avoided, as larvae can be carried as well.
Swimming during morning hours is also riskier, as cooler temperatures can increase the chance of coming into contact with the parasite.
Another suggestion is to rub down briskly with a towel immediately after leaving the water, which will remove or crush the larvae before they get a chance to penetrate the skin. If possible, showering right after swimming has also been shown to help.
Stapley Pharmacy carries a swimmer’s itch cream that can be used as a preventive measure and contains zinc oxide that serves as a protective barrier, according to a previous St. George News report.
Other swimmer’s itch remedies include the following:
- Corticosteroid cream.
- Cool compress to the affected area.
- Bathe in Epson salts or baking soda.
- Soak in colloidal oatmeal baths.
- Apply baking soda paste to the rash.
- Use an anti-itch lotion.
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Copyright St. George News, SaintGeorgeUtah.com LLC, 2018, all rights reserved.
Copyright St. George News, SaintGeorgeUtah.com LLC, 2018, all rights reserved.