What diseases do mosquitoes transmit?

The most important things in brief

• The bites that mosquitoes leave on our skin usually itch for a few days, but they are not dangerous.
• Indigenous mosquito species have so far hardly been suspected of transmitting diseases.
• But that has changed, even if the symptoms are mostly tolerable up to now.
• The situation is different with exotic mosquitoes, which have found their way to Europe and also to Switzerland.

It happens that very soon after a mosquito bite, we realize that our blood has been tapped. Severe itching quickly sets in, and it is not uncommon for relatively large wheals to develop on the skin, which can also become quite hot and do not go away for a few days. A mosquito bite is usually harmless. But it doesn't always stop with itching and swelling - especially mosquito species introduced from Asia sometimes transmit dangerous pathogens.

West Nile virus: the mosquito would not necessarily be the problem

The West Nile virus has only been identified in Europe for a few years. The potentially deadly virus usually causes an abrupt flu-like illness with fever, the incubation period after the sting is about two to 14 days. If the infection is severe, the virus can also cause meningitis. Fortunately, only harmless and mild courses have been observed to date.

The immigrant mosquitoes would not be the problem at all if there were no migratory birds. According to experts, it is they who carry pathogens such as the West Nile virus. The exotic insects only act as carriers - first they bite the birds, then humans or horses, thus ensuring that the viruses find new hosts. Climate change has an unpleasant side effect: because it is getting warmer and warmer in our latitudes, pathogens such as the West Nile virus in mosquitoes also multiply faster. It's not quite that far yet, but it could happen.

What diseases do mosquitoes transmit?

So you have to know: The West Nile virus is most likely brought in by migratory birds - but transmitted by all kinds of mosquito species, including our native ones. However, other viruses have also been detected in these, such as the Batai virus, the Sindbis virus and the Usutu virus, which is related to the West Nile virus.

At the same time, invasive mosquito species have settled here, such as the Asian bush mosquito, the Asian tiger mosquito or the Korean bush mosquito. They are also carriers of these and other viruses, which usually mean mild infections with fever and cold symptoms and usually headaches. More dangerous are Zika or dengue fever, which also spread from these mosquitoes to humans. However, there is no reason to panic: Fortunately, the Swiss climate prevents virus transmission in many cantons and regions.

Already higher danger in warm regions

However, this does not apply to warmer climates. In warm German regions, but also in Ticino, tiger mosquitoes and bush mosquitoes are already native and can no longer be eradicated. And in these warm areas, disease transmission is more likely because the mosquitoes carry more pathogens due to the temperatures.

But even if the worst case does not occur and there is no virus transmission, you do not want to be bitten by the mosquito species that have been introduced: the bites are more painful than those of our native species and usually lead to larger spots on the skin. Allergic reactions are also more common when bitten by invasive mosquito species.