West Nile virus reported in 12 European countries

Twelve countries in Europe have reported locally-acquired cases of West Nile virus so far this year, the EU health agency said Friday, urging the continent to boost its control efforts.

The mosquito-borne virus can cause symptoms similar to flu but in extreme cases it can result in tremors, fever, comas and a lethal swelling of the brain tissue known as encephalitis. It can also cause meningitis.

The 12 countries are Albania, Austria, France, Germany, Greece, Italy, Kosovo, the Netherlands, North Macedonia, Romania, Serbia and Spain, with infections reported in 99 regions, according to the Stockholm-based European Centre for Disease Prevention and Control (ECDC).

Italy and Greece had the highest number of cases — 311 and 157 respectively — while 21 regions across Europe reported their first ever cases.

By comparison, 67 regions in nine European countries had reported cases during the corresponding period in August 2025.

“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,” Celine Gossner, ECDC’s head of food-, water-, vector-borne and zoonotic diseases said in a statement.

“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.”

In Europe, most human infections occur during mosquito season, which generally runs from late spring to autumn, with a peak in transmission between July and September.

There are no approved human vaccines and no specific treatments for the virus, according to the WHO.

Care is limited to managing symptoms and providing supportive hospital treatment for severe cases.

While the mosquitoes that spread West Nile virus (Culex mosquitoes) are already widely present in Europe, the Asian tiger mosquito (Aedes albopictus), which can transmit the dengue and chikungunya viruses, is now established in 16 European countries, double the number from 12 years ago, the ECDC said.

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