Last reviewed by Editorial Team on August 13th, 2018.
What is Swimmer’s itch?
It is a skin condition in which you have an itchy rash after you go swimming or wading. It is also known as cercarial dermatitis, clam diggers itch, and duck itch. You can get swimmer’s itch from freshwater ponds and lakes. Occasionally you can get it from salt water. When you get swimmer’s itch it is from an allergic reaction to microscopic parasites that have burrowed into your skin. The parasite that is associated with this skin condition will normally live in waterfowl along with some of the animals that live near the water. Humans do not make suitable hosts for this parasite and die soon when they are still in your skin. Anyone regardless of age, gender, or race can get swimmer’s itch but it seems children are at a higher risk for getting swimmer’s itch. The reason is that they like to play in shallow water and most of them do not dry off with a towel and instead let the sun dry them. There have been cases of swimmer’s itch around the world. It was first described in 1928 in Michigan. Swimmer’s itch is not contagious so you cannot catch it from another person.
As mentioned with swimmer’s itch you have a rash. This rash looks like reddish blisters or pimples. The rash can appear within minutes after getting in the infested water or days after you have waded or swam in this water. Normally the rash will only appear on skin that is not covered by waders, swimsuits, or wet suits. The symptoms of swimmer’s itch will usually worsen with each exposure to these parasites. You may also have tingling feelings and usually this rash causes you to feel itchy. Normally the rash will go away on its own after a few days but there are some cases where it will last for seven days. It is a rash that is uncomfortable but not serious. Each raised area is the site of the parasite penetrating your skin. Because the rash is itchy you should try not to scratch the area(s) because it could cause the rash to become infected.
Swimmer’s itch is caused by the trematode parasites of which there are many different varieties. The ones that cause swimmer’s itch are of the Gigantobilharzia or Trichobilharzia genus. These parasites will usually infect snails, some mammals like beavers, or birds and it is an accident that they attach themselves to a human. The trematode parasite cannot survive in humans and the parasite will normally die within hours after attaching themselves to a non-suitable host. Most of the time a person will get swimmer’s itch when they are wading or sitting in shallow water. The reason is that there are snails that live near the shore and these snails have been the host for these parasitic worms. The eggs of this parasite get into the water via their host’s feces. The snails are the first host for this parasite and some mammals and aquatic birds are usually the last host.
If you do become infected with swimmer’s itch you can get some over-the-counter topical anti-itching creams. You can also use oral antihistamines to help with the itching. As it will go away on its own in a few days there is no other treatment that needs to be done. If the itching is severe you can soak in a bath to which you have added oatmeal, Epsom salts, or baking soda. You can also make a paste of water and baking soda and apply to the areas that are itching. If you have not seen any improvement within three days you should consult your physician or dermatologist if you have one to make sure that what you have is swimmer’s itch and not another disease or medical condition that has the same symptoms early in the early stages of the disease. Some of these can include impetigo, chickenpox, or herpes.
You can prevent yourself from becoming infected with this parasite by applying topically an insect repellant in which anthelmintic niclosamide or DEET. These are what are known as a parasitic worm killer. Other ways that you can prevent yourself from becoming infected with this parasite can include:
- Make sure that you are choosing your swimming areas carefully. Look to see if there are any warning signs posted about the water being contaminated. You should also avoid wading or swimming in marshy areas where snail are found.
- Avoid wading in the shoreline if possible.
- After swimming or wading make sure that you take the time to rinse your exposed skin immediately after you get out of the water, especially children. After rinsing off vigorously dry your skin with the towel.
- If you see birds or duck near the swimming area do not encourage them to come into the area by feeding them.