Reports of "swimmer's itch" at Willow Creek Reservoir on the Rocky Mountain Front northwest of Augusta, have prompted the Montana Department of Fish, Wildlife and Parks to issue an advisory.

According to the Centers for Disease Control, "swimmer's itch, also called cercarial dermatitis, appears as a skin rash caused by an allergic reaction to certain parasites that infect some birds and mammals.

Left: Cercariae of Austrobilharzia variglandis (left), which can cause swimmer's itch. Right: A group of geese, a preferred host of the parasite that causes cercarial dermatitis. Credit: CDC-DPDx

These microscopic parasites are released from infected snails into fresh and salt water (such as lakes, ponds, and oceans). While the parasite's preferred host is the specific bird or mammal, if the parasite comes into contact with a swimmer, it burrows into the skin causing an allergic reaction and rash. Swimmer's itch is found throughout the world and is more frequent during summer months. Most cases of swimmer's itch do not require medical attention." (source: CDC website)

Symptoms of swimmer's itch may appear withing minutes of swimming in contaminated water, but may take hours or even a few days to appear. Initial symptoms include tingling, burning, or itchy skin. Small reddish pimples appear within 12 hours, and may form small blisters. According to the CDC, the itching may last up to a week, but will gradually go away.

In most cases, home treatments will help alleviate the itching:

  • Use an over-the-counter corticosteroid cream or anti-itch lotion
  • Apply cool compresses to the area
  • Bathe in Epsom salts of baking soda
  • Soak in colloidal oatmeal baths
  • Apply baking soda paste to the rash (mix baking soda with enough water to make a paste)

It's easier said than done, but try not to scratch, which may cause the rash to become infected. For severe itching not helped by the treatments listed above, your doctor may suggest a prescription-strength lotion or cream.

Click HERE for more information on the cause and treatment of swimmer's itch, or call the Lewis & Clark City/County Health Department at (406) 447-8352.