What Is Swimmer’s Itch And Can You Get ‘IT’ In CNY?
The CDC says swimmer's itch is also called cercarial dermatitis.
Swimmer’s itch also called cercarial dermatitis, appears as a skin rash caused by an allergic reaction to certain parasites that infect some birds and mammals. These microscopic parasites are released from infected snails 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. Most cases of swimmer’s itch do not require medical attention. [CDC]
This is what happens in the ecosystem to potentially infect humans:
- The parasite lives in the blood of infected animals such as ducks, geese, gulls, swans, and certain mammals such as muskrats and raccoons and produces eggs that are passed in the feces of infected birds or mammals.
- When the eggs hatch in a pond or lake, small, free-swimming microscopic larvae are released.
- The microscopic larvae search for a certain species of aquatic snail to infect it and multiply.
- Infected snails release a different type of microscopic larvae (or cercariae, hence the name cercarial dermatitis) into the water.
- The snail's larva will swim searching for a suitable host (bird, muskrat) to continue the lifecycle.
- Humans come into contact with the larvae while swimming in these waters.
- Humans are not suitable hosts, but the microscopic larvae burrow into the swimmer’s skin and may cause an allergic reaction and rash. Because these larvae cannot develop inside a human, they soon die.
Here are some common questions according to the CDC:
What are the signs and symptoms of swimmer’s itch?
- tingling, burning, or itching of the skin
- small reddish pimples
- small blisters
The more often you swim or wade in the contaminated water, the more likely you are to develop more serious symptoms.
Do I need to see my health care provider for treatment?
Most cases of swimmer’s itch do not require medical attention. If you have a rash, you may try the following for relief:
- Use corticosteroid cream (Cortizone cream)
- Apply cool compresses to the affected areas
- Bathe in Epsom salts or baking soda
- Soak in colloidal oatmeal baths
- Apply baking soda paste to the rash (made by stirring water into baking soda until it reaches a paste-like consistency)
- Use an anti-itch lotion
Can swimmer’s itch be spread from person-to-person?
Swimmer’s itch is not contagious and cannot be spread from one person to another.
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 present in shallow water by the shoreline. Children are most often affected because they tend to swim, wade, and play in the shallow water more than adults. Also, they are less likely to towel dry themselves when leaving the water.
After an outbreak of swimmer’s itch, 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 generally survive 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.
Is it safe to swim in my swimming pool?
Yes. As long as your swimming pool is well maintained and chlorinated, there is no risk of swimmer’s itch. The appropriate snails must be present in order for swimmer’s itch to occur.
What can be done to reduce the risk of swimmer’s itch, or developing it?
- Do not swim in areas where swimmer’s itch is a known problem or where signs have been posted warning of unsafe water.
- Do not swim near or wade in marshy areas where snails are commonly found.
- Towel dry or shower immediately after leaving the water.
- Do not attract birds (e.g., by feeding them) to areas where people are swimming.
- Encourage health officials to post signs on shorelines where swimmer’s itch is a current problem.