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What’s the ‘sitch’ on swimmer’s itch?

Swimmer’s itch is steeped in local folklore and the myths about what causes it are unfortunately mostly not true. While stories from unlucky itchy swimmers might sound scary, the symptoms aren’t quite as dramatic as the tales you may have heard. In reality, swimmer’s itch is a temporary skin rash caused by an allergic reaction to microscopic parasites that infect some birds and mammals. While the word parasite might make your skin crawl, fear not: the itchiness and bumps that are the telltale signs of swimmer’s itch are not caused by a parasite actually living under your skin. In fact, they cannot survive in humans at all and die almost immediately upon burrowing into your skin.

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Featured

 Summer bummer: How to treat swimmer’s itch

After a nice relaxing day on the lake, there’s nothing worse than discovering a skin irritation. Unfortunately, cercarial dermatitis (also known as swimmer’s itch) is extremely common during the summer months. Thankfully, this parasitic infection is easily treatable and sometimes completely avoidable.

Articles of Interest

Identifying, treating, and preventing swimmer's itch

Swimmer’s itch is a water-borne parasitic disease, and the normal life cycle of the disease-causing parasite involves different animals. Several species of birds (e.g., geese, ducks, gulls) and mammals (e.g., beavers, raccoons) that live near water can be infected with parasites. The adult parasites produce eggs, which are passed in the feces of these animals. If the parasite eggs are released into or near water, they can hatch into larvae (immature forms), which can then infect fresh-water snails.

New Methods for the Detection and Diagnosis of Swimmers' Itch

Swimmers' itch, also known as cercarial dermatitis, is a summer affliction that many of us have suffered following a swim in a freshwater pond or lake, or even occasionally after a dip at the seashore.

Swimmer’s Itch: Incidence and Risk Factors

The onset of swimmer’s itch depends on how humans interact with the lake. Exposures to shallow water and areas with onshore winds are key risks for swimmer’s itch. The more days a person used the lake in July, the higher his or her chances of having any episode. The underlying biological reasons relate to density of snails, movement of cercariae, and cumulative chances of encountering cercariae. In public health terms, people should avoid using shallow water and areas with persistent onshore winds. If they still choose such places, the less often, the better.

Symptoms, treatment and prevention of swimmer’s itch

The parasites that cause swimmer's itch normally live in waterfowl and some mammals. These parasites can be released into the water. Humans aren't suitable hosts, so the parasites soon die while still in your skin. Swimmer's itch is uncomfortable, but it usually clears up on its own in a few days. In the meantime, you can control itching with over-the-counter or prescription medications.

What you should know about Swimmer’s Itch

Many species of parasitic flatworms are naturally occurring in most lakes. However, not all larval species cause swimmer’s itch. The life cycle and host requirements of those species responsible for swimmer’s itch differ widely, and the natural history of most is poorly understood. In North America, at least 30 states and parts of Canada have documented the skin condition. In the United States, the problem appears to be concentrated in the most northern tier of states.

Resources

CDC

Swimmer’s itch, also called cercarial dermatitis, appears as a skin rash caused by an allergic reaction to certain microscopic parasites that infect some birds and mammals. These 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.

DermNet

Swimmer’s itch is an itchy skin rash caused by an allergic reaction to the larval forms of parasitic flatworms released from aquatic snails into fresh and salt water lakes, ponds, and lagoons. Swimmer’s itch is technically called cercarial dermatitis, as it is caused by cercariae, the immature larvae of schistosomes. Many countries have their own local name(s) for swimmer’s itch including ‘duck itch’ (New Zealand), ‘duckworms’ or ‘duck fleas’ (US), ‘hoi con’ (Thailand), ‘kobanyo’ or ‘kubure’ (Japan), ‘sawah’ (Malaysia), and ‘rice paddy itch’ or ‘clam diggers itch’.