West Nile virus is spreading: Bavaria is a hotspot - severe courses can be fatal
Created: 05/15/2022 11:23 am
By: Katarina Amtmann
Mosquitoes spread West Nile Virus (stock image).
© IMAGO / ZUMA Wire
The West Nile Virus is spreading in Germany.
In addition to the East, Bavaria is also a hotspot.
Severe courses can be fatal.
Munich – A buzzing and an itchy wheal on the skin signal: the mosquito is active again.
Exotic species can transmit viruses.
An expert is therefore calling on the population to support science in researching the dangers.
West Nile Virus is spreading in Germany: Bavaria is a hotspot
With spring-like weather, the mosquitoes are out and about again.
In most cases they are just annoying, in rare cases they can make you ill.
Because: For several years it has been known that native mosquitoes can transmit the pathogen of West Nile fever.
Bavaria is a hotspot.
In addition to the Free State, eastern Germany is also badly affected.
"We don't know why yet," said Doreen Werner, biologist at the Leibniz Center for Agricultural Landscape Research (Zalf) in Müncheberg (Märkisch-Oderland), the German Press Agency.
Thuringia, Saxony-Anhalt, Saxony and Brandenburg are affected.
West Nile Virus comes from warmer regions of the world
The West Nile virus originally occurs mainly in warmer regions of the planet.
However, scientists from the Friedrich Loeffler Institute (FLI) had already identified domestic house mosquitoes as carriers of the pathogen.
The virus can overwinter in mosquitoes.
"The warmer it gets, the better the pathogens can develop," explains Werner.
According to the Robert Koch Institute (RKI), an infection is usually not even noticed, and some infected people suffered from flu-like symptoms.
Now especially in East Germany: West Nile virus is spreading (video)
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West Nile Virus: Severe cases can lead to death
Severe courses of West Nile fever are therefore rare - but they can be fatal.
According to the RKI, human cases have been registered in Germany since 2019.
It is to be expected that the pathogen will continue to establish itself in Germany.
Climate change also plays a role in the spread of viruses via mosquitoes.
“Climate change means that the pathogens can multiply better in the mosquitoes.
The central linchpin, however, is increasing globalization,” estimates Werner.
For example, exotic mosquito species can spread from continent to continent via trade in goods, such as the Asian tiger mosquito with the global trade in used tires.
The eggs traveled in the tires as stowaways, explains the mosquito expert.
When these are wetted with water, the larvae hatch.
Good development opportunities at the destination could lead to settlement.
But Werner also cites camping tourism from southern Europe as a possible way of spreading the word.
West Nile Virus – “The colder the winters are, the better it is for the mosquitoes”
At the Zalf, scientists are investigating the spread of mosquitoes that have been introduced in Germany and the question of whether they can also transmit pathogens in this country.
In order for that to happen, for example for a tiger mosquito to spread the pathogen of a tropical disease, it first has to come into contact with infected travelers returning from travel, explains Werner.
To do this, the mosquito and the virus must be compatible – the virus must be able to develop further in the mosquito.
The probability is low, but no longer at zero, says the expert.
The population must be informed and can also support science: the institutes call for mosquitoes to be sent to the Zalf to research their spread.
There the species is determined and entered in a mosquito atlas.
According to Werner, the more than 50 different mosquito species in Germany have different strategies to get through the winter.
They usually hibernate as eggs or larvae, or they survive the winter as adult insects in damp cellars or in warm buildings - for example when they sit near firewood.
"The colder the winters are, the better it is for the mosquitoes," says the researcher, dispelling the myth that freezing cold is harmful to insects.
"Mosquitoes have a built-in antifreeze".
West Nile Virus - weather conditions in spring crucial
According to the expert, when the temperatures fluctuate around 0 degrees, the insects consume a lot of energy because they have to constantly freeze and thaw again.
Many then starved.
In addition, fungal spores are also active at 0 degrees, which overgrow the mosquitoes.
No matter how many or few survive the winter - the weather conditions in spring are decisive.
With the mild temperatures, mosquitoes would have laid their eggs relatively early this year, for example in rain barrels and small puddles of water.
(came/dpa)
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