Climate change extends mosquito activity

From a researcher’s point of view, climate change will prolong the activity of mosquitoes – this means that the risk of virus transmission also increases in Germany. “The earlier in the year and the longer it is warm, the longer the common house mosquito is active outside and also bites,” said biologist Doreen Werner from the Leibniz Center for Agricultural Landscape Research (Zalf) in Müncheberg, Brandenburg.

The development of pathogens in mosquitoes is a temperature-dependent process that could accelerate. The transmission period could also be extended. “That’s not ideal for us. The West Nile virus, for example, will then spread more quickly,” said Werner, who is the initiator of the nationwide mosquito atlas. According to her, this year the mosquito season started in April, about three to four weeks earlier than usual, but did not last longer than usual.

Mosquitoes look for winter quarters in apartments

Currently, house mosquitoes can often be found in basements and apartments, as Werner said. “They like it humid and warm.” Given the cold outside temperatures, the females looked for warmer winter quarters and pushed into the living area. “They also want to bite, but above all they want to get through the winter without frost,” said Werner.

Mosquito findings at home and peak season for professionals

“In a damp basement and with the window ajar, you can have thousands of mosquitoes in the basement,” Werner said. “We are also in high season right now because people see the mosquitoes at home and want to know what they are all about.” She calls on more people to catch mosquitoes and send them to the experts for analysis Mosquito Atlas to send.

West Nile virus can also be transmitted by house mosquitoes

In 2019, according to the Robert Koch Institute (RKI), the first West Nile fever infections transmitted to humans by mosquitoes were reported in eastern Germany. Since then, they have continued to be registered predominantly in Berlin, Brandenburg, Saxony-Anhalt, Saxony and Thuringia. In 2024, individual cases were also detected in other federal states.

According to the RKI, at least 26 people in Germany have now been proven to have been infected with the West Nile virus this year through the bite of a local mosquito. However, the vast majority of infections occur without serious symptoms. Werner emphasized that not every mosquito carries the pathogen, as it first has to become infected from a bird. According to the RKI, around 20 percent of those infected develop a feverish, flu-like illness. Only about one in 100 infected people become seriously ill.