West Nile virus has produced the largest season of locally acquired human infections ever recorded in the EU and EEA, according to the European Centre for Disease Prevention and Control (ECDC). Its weekly threats report for 10 to 16 October 2026 counts 1,715 cases across 13 countries as of 7 October, against a ten-year average of 693 for the same point in the year. The numbers show how quickly a mosquito-borne disease once seen as a southern curiosity is reshaping public health planning.
How big is the West Nile virus season?
The scale of the West Nile virus season is the story. ECDC reports 130 deaths so far. Italy leads with 748 cases, followed by Greece with 445, France with 144 and Spain with 139. Greece and France both recorded their highest annual totals on record.
ECDC’s separate weekly tally to 14 October lists 1,926 cases in 19 countries and 222 affected areas. Because the two counts come from different reporting tables, readers should treat them as two views of one rising trend rather than a single series.
Belgium registered its first human cases of West Nile virus, 15 in total. That detail matters because it shows transmission reaching countries with no history of local infection.
What the severity data say
Higher West Nile virus case numbers have not been matched by a worse clinical picture. About 77% of patients were hospitalised and 57% had neurological symptoms, both within expected levels. The case fatality rate of roughly 8% sits below the ten-year average.
One reading is that surveillance has improved and that more mild infections are being detected. Another is that the disease is simply spreading widely enough to generate more severe cases in absolute terms, even at a steady severity. The data cannot separate the two explanations, and ECDC does not claim to.
Animal data point the same way. Outbreaks in horses reached 510 and outbreaks in birds reached 591, the highest on record for this period. Animal outbreaks often act as an early signal, so those totals deserve attention from veterinary and public health services alike.
Other mosquito-borne threats in the same report
West Nile virus is not the only vector-borne disease in the bulletin. France has logged 163 locally acquired chikungunya cases in 21 clusters, with the largest in Prayssac in Lot (35 cases) and Prignac-et-Marcamps in Gironde (30 cases). Italy has 70 locally acquired dengue cases in seven clusters, and Spain reports four locally acquired Crimean-Congo haemorrhagic fever cases this year.
Taken together, the figures describe a season in which several mosquito and tick-borne diseases circulated at once. That raises the cost of surveillance, because laboratories, hospitals and local authorities must test for and respond to several pathogens in the same weeks.
What the West Nile virus trend means for policy
ECDC notes that activity has declined since the August and September peak, but low-level transmission may continue and more cases are expected. The practical question for health ministries is whether the 2026 season is an outlier or a new baseline.
If it is a baseline, three areas need attention. Mosquito control budgets, which sit mostly with regional and municipal authorities, will have to be planned for longer seasons. Cross-border data sharing between human and animal health services will need to be faster. And clinicians in newly affected countries such as Belgium will need guidance on recognising neurological presentations early.
None of this requires new EU legislation, but it does test how well existing coordination between ECDC, national agencies and veterinary authorities works in practice.
What to watch next
Over the coming weeks, watch for the final tally once late reports are added, whether further countries report first-ever local cases, and how national authorities describe their preparations for 2027. A season that peaked in late summer may be over, but the long-term pattern is the real test.
The 2026 West Nile virus season has already set a European record, and the debate over how to prepare for the next one has only begun.
