The European Food Safety Authority (EFSA) and the European Centre for Disease Prevention and Control (ECDC) said on Thursday that as of early October, 18 European countries had reported 1,855 people being infected by the West Nile virus since the beginning of 2026, including 141 deaths.
“In 2026, WNV has reached record levels in Europe, with the number of human cases and animal outbreaks surpassing historical records,” Giusi Amore, Scientific Officer in EFSA’s Biological Hazards and Animal Health & Welfare unit, told Reuters.
Human cases of the mosquito-borne virus in Europe have risen sharply, with 769 new cases reported since the previous update in September.
According to the report, the number of cases in the EU/EEA now stands at 1,715, which is well above the average of 693 cases recorded over the past decade. Greece and France reported their highest numbers ever at 445 and 144 cases respectively, while Italy remains the most affected European country with 748 cases.
On the animal side, fifteen European countries reported 511 outbreaks in equines and 595 outbreaks among birds. Health officials noted that the transmission season is nearing its end, but low-level transmission may still continue in the coming weeks.
About the virus
West Nile Virus, or WNV, is a mosquito-borne, single-stranded RNA virus in the flavivirus genus, 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. The virus exists in nature in a cycle between mosquitoes and birds.
Mosquitoes, mainly Culex species, get infected by feeding on infected birds and then transmit the virus to humans and other animals through bites. It is not contagious person-to-person, though rare transmission can occur through blood transfusion, organ transplant, or from mother to baby during pregnancy, delivery, or breastfeeding.
About 80% of people infected have no symptoms at all. Around 20% develop a mild, flu-like illness called West Nile fever with fever, headache, body and joint aches, vomiting, diarrhea, rash, and fatigue that can last weeks. In less than 1% of cases the virus affects the central nervous system and causes severe disease such as meningitis, encephalitis, or acute flaccid paralysis.
Severe symptoms include high fever, neck stiffness, confusion, tremors, seizures, muscle weakness, and coma. Recovery can take weeks to months, and the risk of death among those with neuroinvasive disease is about 10%. People over 60, the very young, and those with weakened immune systems or conditions like diabetes, kidney disease, and cancer are at highest risk for severe illness. Symptoms usually appear 2–14 days after a mosquito bite.