The European Food Safety Authority (EFSA) and the European Centre for Disease Prevention and Control (ECDC) said on Thursday that 18 European countries had reported 1,855 human infections with West Nile virus since the start of 2026. As of early October, the count included 141 deaths.
Giusi Amore, a scientific officer in EFSA’s Biological Hazards and Animal Health and Welfare unit, said the virus has reached “record levels” in Europe this year. Both the number of human cases and animal outbreaks have passed historical records, she said.
Human case numbers reach record highs
Since the previous update in September, 769 new human cases have been reported. The total for the EU and European Economic Area now stands at 1,715, well above the average of 693 cases recorded over the past decade.
Greece and France reported their highest case numbers ever, with 445 and 144 cases respectively. Italy remains the most affected country in Europe, with 748 cases.
Animal outbreaks and the end of the season
On the animal side, fifteen European countries reported 511 outbreaks among equines and 595 among birds. Health officials said the transmission season is approaching its close.
They cautioned, however, that low-level transmission could continue in the coming weeks. Authorities are therefore not treating the threat as over.
How the virus spreads and who is most at risk
West Nile virus is a single-stranded RNA virus from the flavivirus genus, which also includes the agent related to Japanese encephalitis. It was first isolated in Uganda in 1937 and now circulates in Africa, Europe, the Middle East, Asia, Australia and North America. In nature, it moves in a cycle between mosquitoes and birds.
Mosquitoes, mainly Culex species, become infected by feeding on infected birds and can then pass the virus to people and animals through their bites. The virus is not spread directly from person to person. Rare cases of transmission have occurred through blood transfusion, organ transplant, or from mother to baby during pregnancy, delivery or breastfeeding.
Most infected people, about 80%, show no symptoms. Around 20% develop a mild, flu-like illness known as West Nile fever, which can cause fever, headache, aches, vomiting, diarrhoea, rash and fatigue lasting weeks. In under 1% of cases, the virus affects the central nervous system and can cause serious conditions such as meningitis, encephalitis or acute flaccid paralysis.
Among people with neuroinvasive disease, the risk of death is about 10%, and recovery can take weeks to months. People over 60, very young children, and those with weakened immune systems or conditions such as diabetes, kidney disease or cancer face the highest risk of severe illness. Symptoms usually appear 2 to 14 days after a mosquito bite.
