Swimmer's Itch (also known as Cercarial Dermatitis) 

Swimmer's itch, also called cercarial dermatitis, appears as a skin rash caused by an allergic reaction to certain microscopic parasites that infect some birds and mammals. These parasites are released 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.

  1. Signs and Symptoms
  2. Treatment
  3. Prevention

Symptoms usually persist for a few days up to two weeks and include:

  • tingling, burning, or itching of the skin
  • small reddish pimples
  • small blisters

Healthcare providers should report suspected cases of swimmer’s itch to the Maricopa County Department of Public Health at 602-506-6767 so that areas of risk can be monitored and posted as necessary.

Want to know more? Visit the CDC's Swimmer's Itch FAQs page.