http://etat.geneve.ch/dt/eau/puces_canard-80-989-2006.html

Apparently the water is already above 20°C in some places so that's when duck fleas develop.

Hello,

You do catch them in the lake when the water is "too" warm. You can try to avoid them by taking a shower as soon as you are out of the water and then dry yourself by rubbing vigorously with a towel...

Hi, thank you for the tips as well as the link! much appreciated. I got some Fenistil to relieve the itching. will be a bit more careful where i go swimming in the lake next time....

I had the same prob but it has gone away after few days ;)

Are they in all the local lakes, or just Leman? How is Annecy?

http://genevalunch.com/2011/05/12/itching-to-swim-in-geneva-lake/

http://genevalunch.com/2013/07/12/warm-weather-lake-geneva-duck-fleas-time-to-beware/

Comment from  a reader of this article 15 hours ago:

Swam at Geneve Plage yesterday and covered in hundreds of little "bites" today - swimmers there beware!

Never been bit and swim in the lake alot. Just started wearing a wetsuit though as I am training for a triathlon I swim at BDP on the side where the current is strong which I think probably helps. Also do the longer open water swims in Versoix and again no issues.

Une baignade sur les bords du lac provoque parfois d'étranges éruptions cutanées. La responsable : une larve microscopique, la cercaire, appelée communément " puce de canard ".

Le ver femelle de ce parasite du canard pond des œufs qui seront rejetés dans l'eau avec les selles d'oiseau. A l'éclosion, les larves colonisent les escargots dans lesquels elles se transforment en cercaires. De retour dans une eau qui a atteint au moins 20 degrés, la cercaire s'attaque au canard pour s'y développer. Mais parfois, elle se trompe de cible et se colle à la peau des baigneurs.

La cercaire pénètre sous la peau, lorsque le baigneur sort de l'eau. Elle y mourra rapidement. Toutefois, elle cause l'apparition de boutons qui ressemblent à des piqûres d'insecte.

Des démangeaisons peuvent survenir pendant quelques minutes après la fin de la baignade. Dans quelques cas, elle peuvent durer plusieurs jours, voire jusqu'à 1 mois. Chez certains individus, le fait de se gratter peut conduire à une infection mineure de la peau.

Actuellement, aucun moyen ou crème répulsive n'est reconnu comme réellement efficace.

Its ok I have a basic entry level speedo one I bought of wiggle when in the UK was £120 personally wouldnt buy anything here as you cant try it on (which first time is a funny experience but they are simple to get on) . They do pinch a bit but depends on your shape. I am not built for swimming at 20+ years of rugby and weights to its a bit big in places but tight in the others if your normal size they are fine. It makes it a lot easier to swim adds bouancy, streamlining and warmth people seem to think just because the water is warm to paddle in its warm to swim in. Quite frankly they are wrong.. Took me a while to get used to it but would t swim without it now tbh. Only downside people look at you like an idiiot when there all in speedos and you are suited and booted.

My husband was bitten earlier this week after swimming in the same Pere du Lac area.  It seems to be pretty bad this year.

Dear All,

here is an iPhone app I just launched: Beach Guide Lake Geneva I : it has all the 114 beaches of Lake Geneva, 200 photos + beach weather (water temperature, UV index etc.), webcam images.

Obvioulsy, I am biassed, but I love it!!! :) 

It also has some info on duck fleas, however best advice is to avoid shallow beaches, or you can try Vaud or French side beaches as there is less problem.

https://itunes.apple.com/us/app/lake-geneva-beach-guide/id666030358?l=hu&ls=1&mt=8

mercryl lauryl is what the locals use! 

I am covered in itchy red spots...so disappointed that I am allergic as I love swimming in the lake. Never had it other years...must be the humidity and lake warth this year

thanks for the advice but I live in France nowhere near la gare. 

I was exaggerating a bit , I maybe got about 20 bites sunday. Was feeling a bit poorly from them, anyway they have nearly gone. It's not a huge deal but you are right antihistamine is a very good idea, mercryl laurel is a natural antihistamine. It's happened twice so far this summer both times at Corsier beach.