Summer is officially here and after the mega heatwave we experienced last week, many of us have been swimming in the lake trying to cool down. With so many stunning beaches along Lac Léman to choose from, one big issue still threatens to interrupt beach-goers’ enjoyment – The dreaded duck fleas or puces de canard!
Read on to find out all you need to know about duck fleas in this article written by Living in Nyon’s founder Catherine over 10 years ago. The advice is still just as relevant today!
Lac Léman beaches
Below is an approximate translation from a publication Carte des Plages du Leman produced by CIPEL. It has a map of all the beaches and places you can swim around the entire lake. It also lists the water quality around all of these beaches and you will be pleased to know that many of these fall into “good quality water” category, a few fall into the “average quality” mark and only one beach (on the French side) out of a total of 116 around the entire lake falls into “bad quality” and where you cannot swim.
Living in Nyon is delighted that Dr Michelle Wright an English speaking General Practitioner has helped with this translation and added some advice of her own.
Here is the translation from the leaflet from CIPEL
“The beaches around Lac Léman are practically all favourable for swimming. 50 metres from the edge, the water is of good quality to swim in, however it is not safe to drink. Even on an extremely clean beach, there may be a risk of ‘swimmers dermatitis’ or ‘duck fleas’, especially in shallow waters which are rich in vegetation and where the temperature is over 20 degrees centigrade. This is a natural phenomenon and bears no relation to pollution.
This dermatological problem is caused by the larvae of a duck parasite that penetrate human skin and cause intense itching. Fortunately it is not dangerous. To avoid ‘swimmers dermatitis’, it is recommended to take a shower immediately after swimming and to dry yourself off vigorously with a towel afterwards. It is also advisable to avoid swimming close to the plants and vegetation near to the water’s edge.
If you do get a rash, you should avoid scratching it in order to prevent secondary bacterial infection. The rash should disappear without any traces within 10-20 days.”
What are ‘duck fleas’?
Duck fleas or puces de canard are actually a relatively common problem that can result from swimming in Lac Léman. They can lead to an itchy skin rash known as ‘swimmers itch’ or ‘swimmers dermatitis’. It is not caused by fleas exactly but by a worm-like parasite whose usual host is the ducks that live in the lake. Whilst you are swimming in the lake, immature forms of the parasite larvae can penetrate ‘mistakenly’ through your skin rather than finding their usual host, a duck. So humans are infected ‘accidentally’. The parasite actually dies when it enters your skin but your body develops an allergic reaction to the parasite and it is this that causes the rash.
What are the symptoms?
On your first exposure to the parasite, you may not have any reaction or develop any symptoms. However, you can still become ‘sensitized’ to the parasite and the next time that you are exposed to it, symptoms can develop.
If symptoms do develop, you may notice tiny red spots at the points at which the larvae have penetrated your skin.
The spots can be tingly or itchy. After a few hours, the spots tend to become bigger and more ‘pimple-like’ or bumpy. Intense itching is usual at this stage. Occasionally, blistering can occur over the next few days. The rash will develop on areas of the skin exposed to the water. So, skin under a swimsuit can be protected and therefore spared from the rash.
If you have developed swimmer’s itch before, you may develop a more severe rash the next time you are exposed to the parasite.
What treatment do I need if I get ‘duck fleas’?
The rash will eventually go away of its own accord but may take between 10-20 days to disappear completely. If you have just a few itchy patches, you may not need any treatment. However, most of the time, itching is quite intense. It is important to control itching because scratching can damage your skin further and sometimes lead to a secondary bacterial infection which may need treatment with antibiotics.
Calamine lotion or an antihistamine may help to treat itching. Antihistamine liquid is available for children. However, do take care when using antihistamines as some can make you drowsy. Take advice from your local pharmacist to make sure that they are safe for you to use.
A mild corticosteroid cream such as 1% hydrocortisone can also sometimes be helpful. Rarely, in very severe cases, steroids taken by mouth may be needed.
How can I avoid ‘duck fleas’?
As suggested by CIPEL:
- Take a shower as soon as you get out of the water. Most of the beaches around the lake have showers available on the lakeside.
- Dry yourself off with a towel after your shower. The brisk rubbing motion with a towel can help to stop the larvae from penetrating your skin.
- Avoid swimming close to the plants and vegetation at the water’s edge. These can be a particular habitat for the parasite
General points about safety around water:
Always take care whilst swimming in the lake or anywhere else. Many drowning incidents could have been prevented.
- Never leave children unattended. If you are watching children playing in or near water, take care not to become distracted.
- Learn to swim. Teach children to swim.
- Don’t swim alone; swim with a buddy.
- Don’t swim whilst under the influence of alcohol.
- Know the water where you are swimming. Remember that lakes and rivers can have strong currents.
- Don’t dive or jump into unfamiliar or shallow water.
- Everyone on board should wear a life jacket when in a boat.