Europe’s mosquito problem is getting harder to control

The European Centre for Disease Prevention and Control (ECDC) warned that Europe needs to strengthen mosquito surveillance and expand the tools available to control the insects as West Nile virus continues to spread and invasive mosquito species become established in new areas.

“The expansion of West Nile virus transmission as well as the spread of invasive mosquito species demonstrate why Europe needs to strengthen its mosquito-control capacity,” said Céline Gossner, ECDC expert in food, water, vector-borne and zoonotic diseases.

The warning comes as the summer transmission season enters its most active period. Six European regions have reported locally acquired West Nile virus infections for the first time this year, while 429 locally acquired cases had been recorded across nine European countries as of August 13, according to the ECDC. Transmission typically peaks in August and early September, meaning the tally is expected to rise.

At the same time, the Asian tiger mosquito, Aedes albopictus, has become established in 16 European countries — twice as many as 12 years ago. The species can transmit dengue and chikungunya, diseases that were once largely associated with tropical and subtropical regions.

A patchwork across Europe

The changing picture is exposing a less visible problem: Europe does not have a consistent system for controlling the mosquitoes that carry these diseases.

A new ECDC survey of mosquito surveillance and control practices found substantial differences between countries in how programmes are organised, funded and implemented. Of the 38 countries and jurisdictions contacted, 26 returned questionnaires.

The report found that many mosquito surveillance and control programmes rely on short-term funding and lack long-term planning. Responsibility can also sit at different levels of government — national, regional or local — making approaches difficult to coordinate across borders.

That matters because mosquitoes do not respect those borders.

“For effective mosquito control, we need close cooperation in Europe and an integrated approach that brings together mosquito monitoring, community engagement, and targeted mosquito control solutions that take environmental impact into account,” Gossner said.

The ECDC says reactive mosquito control is often ad hoc and focused on adult insects, while longer-term strategies to eliminate invasive populations are frequently missing. For Aedes mosquitoes, countries use a mixture of chemical and non-chemical measures, including efforts to target immature mosquitoes and campaigns to get communities involved.

Climate change is adding urgency to the problem. Longer and more intense transmission seasons are already being observed for West Nile virus, dengue and chikungunya, according to the ECDC's new report. Warmer conditions can create more favourable environments for mosquitoes and extend the periods during which viruses can circulate.