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Swimmer's itch is a rash caused by an allergic reaction to the larvae of certain parasites. The parasites can get under your skin when you swim in freshwater (such as lakes and ponds) and sometimes salt water. But you can't get swimmer's itch from swimming pools that are treated with chlorine.
The tiny parasites infect birds or mammals and lay eggs. Bird and mammal droppings that contain the eggs get into lakes and ponds. The eggs hatch into larvae, which then infect snails. The snails in turn release the larvae into the water, where the larvae look for a host. If they come in contact with people, the parasites can burrow under the skin. This causes an allergic reaction and a rash.
But the larvae can't survive in humans, so the parasites die. As a result, the rash usually goes away on its own and doesn't need treatment. The rash can't be spread from person to person.
Symptoms of swimmer's itch include:
A doctor can diagnose swimmer's itch by looking at your skin and asking if you've been swimming in ponds or lakes.
In most cases, swimmer's itch goes away on its own, so you don't need to see a doctor.
To treat the itching at home, you can:
Try not to scratch the rash. This could lead to an infection.
Call your doctor if you still have a rash after 1 week or if you have signs of infection, such as:
To lower your chance of getting swimmer's itch:
Other Works Consulted
Centers for Disease Control and Prevention (2011). Parasites—cercarial dermatitis (also known as swimmer's itch). Available online: http://www.cdc.gov/parasites/swimmersitch/faqs.html.
Current as of:
March 12, 2014
William H. Blahd, Jr., MD, FACEP - Emergency Medicine & H. Michael O'Connor, MD - Emergency Medicine
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