Heat raises risk of swimmer’s itch in shallow water

Prolonged heat is increasing the risk of swimmer’s itch, particularly in still, shallow water, ORF Vorarlberg reports. Bathers may develop skin redness, itching or raised welts at current water temperatures, although paediatricians say there has been no increase in cases so far.

Cases can become more common when water remains above 24 to 26 degrees Celsius for extended periods. Near the shore in Bregenz, the water is currently around 27 degrees at a depth of 0.5 metres. Gerhard Hutter from the water quality department of the Vorarlberg Environmental Institute said these temperatures promote the formation of cercariae, the organisms responsible.

Parasites cause an itchy rash

Cercariae are larvae of parasitic flatworms that can naturally occur in water. They normally infect waterfowl, especially ducks, but contact with human skin can trigger an allergic reaction. Symptoms include itching, red patches and a rash with small pustules.

Humans are an accidental host. If the larvae penetrate the skin, they cause a superficial, itchy rash but cannot progress further into the body and eventually die, according to Hutter and the Federal Ministry of Health. The condition is considered unpleasant but harmless.

How to reduce the risk

Hutter advises avoiding shallow, still shoreline areas with abundant aquatic plants. Bathers should also avoid feeding ducks and other waterfowl at swimming areas. After swimming, they should shower immediately, dry themselves with a towel and change out of wet swimwear.

The formation of cercariae is unrelated to water quality. Water quality at all bathing sites in Vorarlberg is currently rated excellent, with further measurements planned for mid-August.

Cercariae can develop in both fresh and salt water, meaning swimmer’s itch can also occur while on holiday. Children are often affected because they tend to play in shallow water.