Swimmer’s Itch (Schistosome Dermatitis)

Swimmer’s itch is a temporary skin irritation caused by microscopic parasites that normally infect birds and mammals. These parasites are released by infected snails into freshwater (or saltwater) and can mistakenly penetrate human skin, causing an allergic reaction and rash.

Ducks, especially common and red‑breasted mergansers, are the primary hosts in Great Pond and Long Pond.

Swimmer's Itch Diagram

Symptoms

  • Tingling, burning, or itching skin
  • Small reddish pimples
  • Small blisters

Most cases resolve on their own without medical treatment.

More on Swimmer’s Itch from Maine DEP
More from the CDC

The Belgrade Lakes Association Swimmer’s Itch Program

The BLA monitors swimmer’s itch occurrences in Great and Long Pond. In past years, the program included capturing, inoculating, and relocating mergansers—the primary hosts of the parasite—with help from the USDA’s Wildlife Services. Trained BLA volunteers have made significant contributions to this effort.

We continue to need your help! Please report:

  • Merganser sightings
  • Known nesting areas
  • Any suspected cases of swimmer’s itch

Call the BLA at (207) 512‑5150 or USDA‑APHIS at (207) 629‑5181.

Identifying Mergansers

Common Merganser Male
Common Merganser – Male
Common Merganser Female
Common Merganser – Female
Red Breasted Merganser Male
Red‑breasted Merganser – Male
Red Breasted Merganser Female
Red‑breasted Merganser – Female

Learn more about Common Mergansers
Learn more about Red‑breasted Mergansers

Merganser Family

Reducing Merganser Broods on Great Pond
2009 Final Report, USDA Wildlife Services