Gorgeous summer weather isn’t just ideal for swimmers—annoying duck fleas also thrive in high temperatures. In local bodies of water, they lie in wait for their victims and cause severe itching. This is actually a case of mistaken identity: the parasites cannot distinguish between humans and animals.
Strictly speaking, duck fleas are not fleas, but rather the larvae of flukes, also known as cercariae. They live as parasites in the intestines of native ducks, geese, and swans. The worm eggs enter the lakes through the feces of waterfowl. When the larvae hatch, the first things they attack are water snails. When water temperatures exceed 20°C, the larvae (cercaria), which are about one millimeter in size, leave the snails and set out in search of a host.
“In the worst-case scenario, patients can’t sleep a wink at night because of the itching.”
Annoying, but harmless
If someone happens to be swimming by, it will be unpleasant for them. This is because the larvae cannot tell the difference between human skin and duck skin and try to burrow into it. But human skin is too thick for the larvae—they get stuck inside and are killed by our immune system. They cause what is known as “swimmer’s dermatitis,” which manifests as a red rash accompanied by severe itching, hives, a burning sensation, tingling, and numerous pustules and small blisters. It is important to note that the symptoms caused by duck fleas are generally harmless. But the annoying itching can last up to two days, and without treatment, the inflammation doesn’t subside until 10 to 20 days later.
How to Treat Duck Fleas
“How bothersome the itching is perceived to be varies from person to person,” says Claudia Lang, senior physician at the Dermatology Clinic. “Just like pain processing, the body’s response to itching varies greatly from person to person. Patients who experience it a second time may react very strongly, as the immune response can be more severe the second time around. In the worst-case scenario, patients can’t sleep a wink at night because of the itching, which naturally affects their daily lives.”
In addition, there is a small risk of secondary infections caused by vigorous scratching, similar to what happens with mosquito bites. Not every encounter with duck fleas has to end in a pustule nightmare. “There are pills and ointments that relieve the itching,” Lang explains. “If someone is really suffering from severe itching, we can prescribe lotions containing polidocanol. This is a local anesthetic that soothes the skin. There are also anti-allergy pills, known as antihistamines, that help relieve the itching. Some are even available over the counter.” Fortunately, swimmer’s itch is not contagious.
What works against duck fleas?
Prevention is still the best approach: You should avoid swimming spots with particularly large numbers of waterfowl, since that’s where duck fleas thrive—just as they do in shallow, warm water. In addition, you can prevent these pests from getting into your skin by showering thoroughly after bathing and drying off vigorously. If you want to play it safe, you should only swim in flowing water. In rivers, duck fleas aren’t really a problem. The same is true in the ocean: the parasites cannot survive in saltwater.
Five Simple Tips for Getting Rid of Duck Fleas
- Do not swim where there are many waterfowl
- Shower thoroughly immediately after bathing
- Rub vigorously with a cloth until dry
- Avoid warm, shallow water
- Change clothes after swimming
