Posted by Dr Michelle Wright
My name is Dr Michelle Wright. Welcome to my Health Matters podcast.
I’m a British-trained doctor and General Practitioner, living and working in Switzerland for over 20 years.
In each episode, I bring you clear, evidence-based health information, relevant to your life here.
As summer arrives in Switzerland, so does a small but increasingly important public health concern: the Asian tiger mosquito, Aedes albopictus.
Although tiny, the tiger mosquito is one of the world’s most successful invasive species. Originally from Southeast Asia, it has spread across Europe through international travel and transport. In Switzerland, it was first detected in Ticino in 2003, in Valais in 2019, and became established in the Canton of Vaud in 2022.
Why is the Asian tiger mosquito attracting so much attention?
Well, there are two main reasons.
First, it’s extremely aggressive. Unlike our native mosquitoes, which usually bite in the evening or at night, the tiger mosquito bites during the day. And it often bites the same person repeatedly, so it can make gardens, balconies, and outdoor spaces unpleasant to use.
Second, and more importantly, it has the ability to transmit infections including dengue, chikungunya and Zika.
These viruses are mainly found in tropical and subtropical regions of the world. However, because international travel is so common, there is the potential for infected travellers to bring them back to Europe, and local transmission becomes possible if tiger mosquitoes are present.
Dengue is a viral infection that typically causes high fever, severe headaches, muscle and joint pain, and sometimes a rash. In rare cases, it can lead to serious complications and bleeding.
Chikungunya again causes fever but also intense joint pain, which can persist for weeks or even months after the infection.
Zika virus infection is usually mild, with no symptoms in up to 80% of cases. However, if symptoms do develop, again fever, rash, and joint pain are the main ones. But importantly, pregnant women who are infected can pass the virus to their developing baby which can lead to a risk of neurological problems for the baby.
At the moment, the risk of these diseases being transmitted locally in Switzerland remains very low. However, health authorities are working hard to keep tiger mosquito populations at low levels because increasing mosquito numbers raises the risk of local outbreaks if infected travellers return from affected countries.
An important point is that the tiger mosquito doesn’t spread rapidly by flying. In fact, it usually travels only short distances in this way. Instead, it spreads mainly by hitching rides in cars, trucks, buses, and other forms of transport. This is why it has gradually expanded from neighbouring countries into different regions of Switzerland.
According to the Swiss Mosquito Network surveillance system, complete eradication is unrealistic. The tiger mosquito will likely continue spreading as climate conditions become increasingly favourable. However, its population density can be controlled, and this makes a major difference.
Ticino provides an encouraging example of this. Through years of surveillance, public education, and preventive measures, authorities and residents have succeeded in stabilising, and even slightly reducing, the tiger mosquito population there. According to the Swiss Mosquito Network, Ticino is currently the only region in Europe to have achieved such results on a large scale.
What can each of us do?
The key message is simple: fight the larvae, not the adults.
Adult tiger mosquitoes are difficult to control. Once they are flying, there are very few effective options. Broad insecticides are not used because they would also kill many beneficial insects.
Instead, prevention focuses on eliminating breeding sites.
Tiger mosquitoes lay their eggs in very small amounts of stagnant water. A flowerpot saucer, a watering can, a bucket, a rainwater collection container, a blocked gutter, or even a small puddle trapped in a wall cavity can be enough.
So, to reduce breeding, it’s important to:
- Empty containers that hold standing water at least every three days.
- Turn unused containers upside down.
- Clean the edges of water containers regularly, especially in spring, to remove eggs that survived the winter.
- Cover rainwater tanks with fine mesh or fabric.
- Check balconies, terraces, gardens, and shared outdoor spaces.
Experts recommend starting these measures as early as May and continuing them through September.
And finally, it’s important to stay vigilant.
A mosquito that is active and biting aggressively during the day is very likely to be a tiger mosquito. Suspected sightings can be reported through the Swiss Mosquito Network website, helping specialists track the spread and support local control efforts.
The tiger mosquito is unlikely to disappear from Switzerland. But with continued surveillance, cooperation between authorities and residents, and simple preventive actions at home, we can significantly reduce its numbers and limit the health risks it poses.
That’s it for this episode of Health Matters. If you found it useful, please like, share, and follow on Spotify – it helps others find reliable health information in English.
