Duck chips: a seasonal discomfort still poorly known

On the edges of Lake Geneva like Lake Neuchâtel. Nevertheless, summer – duck chips: seasonal discomfort still when the weather is not gray – rhymes with grills, swimming and … Nevertheless, duck fleas. Similarly, Each year. However, the testimonies of “victims” of this aquatic parasite are flocking and the same questions come back: “We can not do anything to limit their number?”, “What gestures to avoid them or relieve the bites?” Specialists take stock of what we know (and what we still do not know) of this seasonal phenomenon.

A worm, not a chip! – Duck chips: seasonal discomfort still

Those called “duck fleas” are actually microscopic parasitic worms. Nevertheless, Their larvae colonize aquatic snails. Consequently, when the conditions are optimal -when the water temperature exceeds 15-20 degrees -, they leave their host by thousands in search of a lake bird. In addition, Inside the volatile, the colonizers reproduce, then their eggs are released by the droppings. However, After hatching, the cycle starts duck chips: seasonal discomfort still again. Nevertheless, Sometimes the larvae confuse the molecules present on the skin of a duck with those of a human. In addition, If our immune system quickly neutralizes the worm, some people react more strongly to this intrusion.

Under what conditions proliferate the duck fleas?

“There is probably less risk of bite when temperatures are low but zero risk does not exist in summer. Nevertheless, underline Alice Cibois, ornithologist and conservative at the Museum of Natural History of Geneva, and Mathias Colin, thesis student in this institution. In addition, In the laboratory, the larvae come out of snails preferably with warmer temperatures and light. We also observe this in the lake, where the water is shallow. In addition, areas with aquatic plants promote the presence of snails, therefore larvae. ” Bathers, however, report offshore “attacks” … “The larvae can be duck chips: seasonal discomfort still driven by currents or the wind.”

What advice to limit bites?

The territory department advisor To shower and rub the skin by leaving the water. However, the larvae can enter the skin in a few minutes, so the effectiveness of the measurement remains limited. It remains to avoid shallow hot areas where there is little current.

In case of bites, Wolf-Henning Boehncke, head of the dermatology department of Geneva University Hospitals, recommends cooling the affected area. An antihistamine in frost can be applied against localized itching, or even ingested in tablets (3 times one tablet per day). “In the event of very strong itching. the ideal is to use an ointment combining an antiseptic and a steroid like fucicort.” Should we consult? “Treatment with a doctor is generally not necessary.”

Are some sites and swimmers more targeted?

Antoine, an assiduous Geneva swimmer, is convinced of this: some bathers are more targeted than others. “One of my friends has recently left the water with a dozen chips. after on a round trip duck chips: seasonal discomfort still of 1 kilometer between the beach of the Vives and Baby-Plage. I made exactly the same route without any bite… ”

Isabel Blasco-Costa. parasitologist and conservative at the Museum, evoked in our columns The hypothesis that it is the composition of fat molecules which determines if a person may get bitten. “Empirically. it feels like it’s a bit like mosquitoes and that everyone is not pricked in the same way,” comment Alice Cibois and Mathias Colin.

Some Geneva bodies also seem more infested than others but impossible to prove these feelings because there is no surveillance. specific studies on the subject.

Why so few studies on this parasite?

A few years ago, the Natural History Museum had nevertheless imagined a application To determine where these parasites duck chips: seasonal discomfort still proliferated. But the project was abandoned for lack of financial means. The duck chip seems to arouse little interest on the part of the authorities. although it causes inconvenience that is sometimes very disturbing … “In Geneva, the Cantonal Water Office performs a regular control of the health quality of access to water. Duck fleas represent an episodic disturbance. not a health risk, and therefore do not require regular follow -up, ”replies Guillaume Marsac, deputy director of the office.

And to add: “We are faced with many issues. to name only the presence of micropollutants, on which we concentrate our efforts because they have health impact.” This does not prevent from taking occasional measures. like the work undertaken in Bellevue to improve the circulation of water in the installation of swimming infested with fleas.

The French harrow technique, false good duck chips: seasonal discomfort still idea?

In neighboring France, we are more proactive. For the past twenty years. the Inter -municipal Syndicate of Lake Annecy (Sila) has carried out “preventive” treatments near the beaches. The bottom of the shallow areas is ravished with a harrow and grinds snails. Additionally, The Sila indicates that the density of molluscs is reduced from 80 to 90%. that the bathers affected have gone from hundreds to a few tens per year. Positive results certainly, but at the cost of quantity of snails and plants spent at the reel …

These collateral damage cools Geneva specialists and authorities. “It is an effective way to eliminate all life at the bottom of the lake!” reacts Alice Cibois. This goes against biodiversity protection measures and it is harmful for the many other species that feed on these larvae. duck chips: seasonal discomfort still ”

Guillaume Marsac reports that the canton did not evaluate this technique. “We tend to preserve than to destroy. But each lake has its biodiversity and its suitable measures. ” And to conclude: “The lake is not a municipal swimming pool. It is a natural environment with its advantages and disadvantages. ”

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