Swimmer's Itch
Causes, control efforts, and treatment
What causes swimmer’s itch?
Swimmer’s itch is an itchy skin rash caused by microscopic parasites naturally found in freshwater lakes. These parasites live in aquatic snails and waterfowl, especially common mergansers. Humans are not a natural host, but the parasites can penetrate skin and cause irritation when people swim or wade in near-shore waters.
Research shows that flightless common merganser ducklings are the primary carriers because they remain on the lake all summer and can become highly infected.
What’s been done — and what’s ongoing
The Higgins Lake Property Owners Association (HLPOA) was instrumental in advancing research into the causes of swimmer’s itch at Higgins Lake. Working with leading scientists and wildlife professionals, HLPOA helped develop a science-based, humane approach to controlling swimmer’s itch. Those efforts led directly to the creation of the Higgins Lake Swimmer’s Itch Organization (HLSIO), which has coordinated research, monitoring, and control efforts for more than a decade.
Key actions include:
- Lake-wide bird surveys each spring and summer
- Sealing merganser nesting sites
- GPS tracking and ongoing research to improve control strategies
- Since 2015, humane trapping and relocation of merganser hen and ducklings under state and federal permits
- Snail monitoring, which showed dramatic reductions in parasite levels when mergansers are relocated.
While swimmer’s itch can’t be completely eliminated from a natural lake, these efforts have significantly reduced risk and reported cases across Higgins Lake.
Treatment: what to do if you get swimmer’s itch
Swimmer’s itch usually clears on its own within a few days to two weeks.
Helpful treatments include:
- Rinse skin promptly after swimming and towel dry vigorously
- Apply anti-itch lotions (calamine or menthol-based)
- Use 1% hydrocortisone cream to reduce inflammation
- Take oral antihistamines for itching (if appropriate for you)
- Avoid scratching to prevent infection
If symptoms are severe, prolonged, or show signs of infection, contact a healthcare provider.
How you can help
Community reporting is essential for keeping swimmer’s itch levels low:
HLSIO Donations
Help HLSIO by donating to prevent and protect our lake
HLSIO Donations
Help HLSIO by donating to prevent and protect our lake
Learn more:
Detailed Scientific Studies
Studies, annual reports, and ongoing research relying on continued research, monitoring, and community involvement provided by the HLSIO foundation.