Assessment
Questionnaire

Have a symptom?
See what questions
a doctor would ask.
 
Articles » Cercarial dermatitis: DPD
 

Cercarial dermatitis: DPD

Article title: Cercarial dermatitis: DPD

Conditions: Cercarial dermatitis

Source: DPD


 


Cercarial dermatitis
Swimmer's Itch
(SIR-care-ee-uhl DER-muh-TIGHT-iss)


What is swimmer's itch?

Swimmer's itch, also called cercarial dermatitis, is a skin rash caused by an allergic reaction to infection with certain parasites of birds and mammals. These microscopic parasites are released from infected snails to swim in fresh and salt water, such as lakes, ponds, and oceans used for swimming and wading. Infection is found throughout the world. Swimmer's itch generally occurs during summer months.

What are the signs and symptoms of swimmer's itch?

Within minutes to days after swimming in contaminated water, you may experience tingling, burning, or itching of the skin. Small reddish pimples appear within 12 hours. Pimples may develop into small blisters. Itching may last up to a week or more, but will gradually go away.

Because swimmer's itch is caused by an allergic reaction to infection, the more often you swim or wade in contaminated water, the more likely you are to develop more serious symptoms. The greater the number of exposures to contaminated water, the more intense and immediate symptoms of swimmer's itch will be.

Be aware that there are other causes of rash that may occur after swimming in fresh and salt water.

Do I need to see my health care provider for treatment?

No. Most cases do not require medical attention.

If you have a rash, you may try the following for relief:

  • corticosteroid cream
  • cool compresses
  • bath with baking soda
  • baking soda paste to the rash
  • anti-itch lotion
  • Calamine* lotion
  • colloidal oatmeal baths, such as Aveeno*

Try not to scratch. Scratching may cause the rash to become infected. If itching is severe, your health care provider may prescribe lotion or creams to lessen your symptoms.

How does water become infested with the parasite?

The adult parasite lives in the blood of infected animals such as ducks, geese, gulls, swans, as well as certain aquatic mammals such as muskrats and beavers. The parasites produce eggs that are passed in the feces of infected birds or mammals.

If the eggs land in the water, the water becomes contaminated. Eggs hatch, releasing small, free-swimming larvae. These larvae swim in the water in search of a certain species of aquatic snail.

If the larvae find one of these snails, they infect the snail and undergo further development. Infected snails release a different type of larvae (cercariae, hence the name cercarial dermatitis) into the water. This larval form then searches for a suitable host (bird, muskrat) so they can start the lifecycle over again. Although humans are not a suitable host, the larvae burrow into the skin of swimmers, which may cause an allergic reaction/rash. The larvae cannot develop inside a human and they soon die.

Can swimmer's itch be spread from person-to-person?

No.

Who is at risk for swimmer's itch?

Anyone who swims or wades in infested water may be at risk. Larvae are more likely to be swimming along shallow water by the shoreline. Children are most often affected because they swim, wade, and play in the shallow water more than adults. Also, they do not towel dry themselves when leaving the water.

Once an outbreak of swimmer's itch has occurred in water, will the water always be unsafe?

No. Many factors must be present for swimmer's itch to become a problem in water. Since these factors change (sometimes within a swim season), swimmer's itch will not always be a problem. However, there is no way to know how long water may be unsafe. Larvae are generally infective for 24 hours once they are released from the snail. However, an infected snail will continue to produce cercariae throughout the remainder of its life. For future snails to become infected, migratory birds or mammals in the area must also be infected so the lifecycle can continue.

What can be done to reduce the risk of swimmer's itch?

  • Avoid swimming in areas where swimmer's itch is a known problem or where signs have been posted warning of unsafe water.
  • Avoid swimming near or wading in marshy areas where snails are commonly found.
  • Towel dry or shower immediately after leaving the water.
  • Encourage health officials to post signs on shorelines where swimmer's itch is a current problem.
  • Do not attract birds by feeding them to areas where people are swimming.
For further information on protecting yourself from recreational water illnesses, please visit www.healthyswimming.org

Is my swimming pool safe to swim in?

Yes. As long as your swimming pool is well-maintained and chlorinated, there is no risk of swimmer's itch.

This fact sheet is for information only and is not meant to be used for self-diagnosis or as a substitute for consultation with a health care provider. If you have any questions about the disease described above or think that you may have a parasitic infection, consult a health care provider.

 

 

By using this site you agree to our Terms of Use. Information provided on this site is for informational purposes only; it is not intended as a substitute for advice from your own medical team. The information on this site is not to be used for diagnosing or treating any health concerns you may have - please contact your physician or health care professional for all your medical needs. Please see our Terms of Use.

Home | Symptoms | Diseases | Diagnosis | Videos | Tools | Forum | About Us | Terms of Use | Privacy Policy | Site Map | Advertise