- An itchy harmless rash caused by tiny parasites in fresh water lakes
- Less commonly occurs in salt water (called clam digger's itch)
Symptoms of Swimmer's Itch
- Itchy skin rash
- Begins within 2 hours of swimming in a fresh water lake. It can also occur in salt water, although this is less common.
- The rash only occurs on areas exposed to the lake water. The legs are commonly involved. The bathing suit area may be spared.
- The first symptom is itching or burning of the skin.
- Then small red spots appear within 1 or 2 hours. The spots appear at sites where a parasite has gotten into the skin.
- The spots turn into small red lumps over 1 or 2 days.
- The spots can be quite itchy for up to 7 days. The rash gradually fades away over 2 weeks.
- Also called cercarial dermatitis
- Swimmer's itch is caused by a very tiny parasite. You can only see it with a microscope. It gets into the skin of humans by mistake.
- The rash and itching are the body's allergic reaction to parasites in the skin.
- This parasite can be found in lakes in every state (US). It is also found in lakes in Canada and over 30 other countries. In the US, Michigan and other Great Lakes region states are most involved.
- It is less common in salt water (called clam digger's itch).
- The parasites get into the lakes from the droppings of water birds. Their normal life cycle involves birds and snails. It dies off quickly in human skin.
Repeat Contact (Exposure) and the Body's Reaction
- Swimmer's itch is the body's allergic reaction to the parasite. Each time the body is exposed, the more intense the reaction will be. This is called sensitization.
- After first-time contact, the onset of itching and rash takes 1 to 2 weeks.
- For repeat contact, the onset of itching and rash is within 2 hours.
- The more the exposures, the faster the rash occurs. It also causes the rash and itching to become more severe.