West Nile virus in Europe: Dutch deaths rise, while France and Spain report continued animal and human expansion

West Nile virus activity remained substantial across Europe during this week, with some of the clearest new signals coming from the Netherlands, France, Italy and Spain. The Netherlands reported four additional deaths alongside new infections in people, horses and birds. France added 28 locally acquired human cases in one week while its equine outbreak reached 364 symptomatic cases, and Spain recorded the first equine outbreak of the season in Aragón.

The figures below cover developments reported between 24 September and 2 October 2026. Because national surveillance systems update on different days and use different definitions for animal cases and outbreaks, they should not be combined into a single European total.

Netherlands: 12 new human infections and four additional deaths

The Netherlands recorded one of the most notable developments of the week. On 1 October, the Dutch National Institute for Public Health and the Environment (RIVM) reported 12 additional human infections since its previous update of 24 September. Four of these patients had died, bringing the 2026 total to 56 reported infections and nine deaths. All 12 newly reported infections were acquired through mosquito bites.

The geographical concentration remains strongest in South Holland, which accounts for 32 human cases, followed by Utrecht with 12, North Holland with five, North Brabant with four, Gelderland with two and Overijssel with one. RIVM nevertheless considers that the outbreak has probably passed its peak because the number of new infections is declining.

Animal surveillance shows the same slowing but continuing circulation. During the week, 14 additional horses tested positive, increasing the Dutch total from 136 to 150 horses. Seven more birds were also confirmed, taking the national total to 178 infected birds. No additional positive mosquito pools were detected; the cumulative total remains four.

The Dutch epidemic remains particularly informative from a One Health perspective because the same transmission system is being followed simultaneously in people, horses, wild birds and mosquitoes.

France: 28 additional human cases and 364 symptomatic horses

France also recorded a substantial increase this week. Santé publique France reported 145 locally acquired human infections as of 28 September, compared with 117 the previous week — an increase of 28 cases in seven days. Transmission now extends across Provence-Alpes-Côte d'Azur, Occitanie, Île-de-France, Auvergne-Rhône-Alpes, Nouvelle-Aquitaine, Pays de la Loire and Centre-Val de Loire. For 14 patients, the precise location of infection could not be established.

The animal situation is considerably larger. An epidemiological update issued on 30 September by the French equine veterinary community, based on data from the national reference laboratory, reported 364 symptomatic equine cases and 18 positive avian cases since the start of the surveillance season. WNV circulation has now been demonstrated in 33 departments across eight regions. This represents a major increase from the 253 equine cases documented by 11 September and confirms that equine transmission continued throughout the second half of the month.

Île-de-France illustrates how closely the human and animal signals now overlap. By 28 September, the region had recorded 23 autochthonous human cases, including 13 neuroinvasive infections and three deaths, alongside equine and avian detections.

Italy: 27 more human infections in one week

Italy remains the largest human focus in Europe. The national surveillance bulletin published on 1 October recorded 727 confirmed human WNV infections as of 30 September, up from 700 one week earlier. Of these, 383 were neuroinvasive, 247 presented as West Nile fever, 93 were asymptomatic blood donors and several had other presentations. Fifty-four deaths had been reported, including one imported case.

The geographical footprint also expanded during the week. WNV circulation is now documented in 85 provinces across all 20 Italian regions, compared with 83 provinces in 19 regions a week earlier. This integrated definition includes evidence from humans, animals and vectors.

Italy therefore remains distinct from the newer north-western European focus: rather than an emerging localised event, it represents widespread and established transmission across a large part of the country.

Spain: first 2026 equine outbreak in Aragón

The main new Spanish animal signal came from Aragón, where the first equine West Nile outbreak of 2026 was reported in San Esteban de Litera, Huesca.

The affected premises housed 30 susceptible equids, with one animal reported infected. This extends the geographical range of documented animal circulation into Aragón after previous outbreaks in Catalonia, Andalusia, Castilla-La Mancha and Extremadura. Spain had accumulated 29 animal WNV outbreaks in 2026 by the beginning of October.

The detection is epidemiologically relevant because it represents another north-eastern expansion of equine activity rather than continued concentration solely in the traditional southern Spanish hotspots.

The late-season pattern is therefore no longer confined to southern Europe. Animal surveillance, particularly in horses and wild birds, continues to reveal active virus circulation across a broad band extending from the Mediterranean to north-western Europe.