Hungary is now Europe's West Nile virus hub, 111 autochthonous cases in 2024 mapped it

Hungary reported 113 human West Nile virus cases in 2024. A hundred and eleven of them were acquired inside the country. Ninety-two percent were neuroinvasive. Seven point nine percent were fatal. Every sequenced strain was lineage 2. And a single genomic study, published this spring, has now mapped the country as the persistent transmission hub of European WNV, with two viral corridors running outward from it, one west along the Danube and one southeast into the Balkans.

That is the institutional picture European public health now has to plan against.

What Hungary actually did in 2024

The numbers come from a comprehensive genomic and epidemiological study by Anna Nagy and colleagues at the National Public Health Center in Budapest, published in April 2026 in Eurosurveillance. Hungary has been a known WNV presence since 2004, but the 2024 season was the largest geographical distribution of the virus ever recorded in Europe. The 113 cases represented a 3.7-fold increase on 2023, lifting incidence from 0.31 to 1.16 per 100,000 population in a single year.

Of the 113 cases, 111 were autochthonous, acquired within Hungary, and only two were imported. Sixty-five point five percent were male. Sixty-three point seven percent were over 60. The clinical picture was severe: 104 of the 113 cases (92 percent) presented with neuroinvasive disease, meningitis, encephalitis, or acute flaccid paralysis, and nine patients died, for a case fatality ratio of 7.9 percent. The seasonal peak fell in epidemiological weeks 35 and 36, late August and the first week of September.

The geographic distribution was unusually wide. County-level incidence was highest in Fejér, on the western side of the Danube roughly halfway between Budapest and the southern border. Elevated incidence also appeared in Jász-Nagykun-Szolnok, Csongrád-Csanád and Heves, the Great Plain counties running south and east of Budapest toward the Serbian and Romanian borders.

What the genomes actually say

The Nagy team's contribution is not just a bigger case count. They sequenced 55 strains from 38 humans, 15 birds and two Culex pipiens mosquito pools, then combined those with 637 European WNV genome sequences collected between 2004 and 2024 to build a time-scaled Bayesian phylogeography of the virus across the continent. Every one of the 55 Hungarian strains was lineage 2, and Hungarian viral diversity sits inside six of the eight major European WNV clades. The country has not merely been a recipient of WNV introductions from elsewhere in Europe; it has been a source of them, repeatedly, since the lineage first established itself in Hungary in 2004.

Continuous spatial diffusion modelling identified two persistent viral corridors out of Hungary. The first runs westward along the Danube, into Austria and the rest of central Europe. The second runs southeastward, into the Balkans, Serbia, Romania, North Macedonia, and from there further south. Both corridors carry northward expansion as a structural feature. The viral traffic between Hungary and its neighbours is bidirectional, but Hungary is the centre of gravity.

That is the institutional meaning of the paper's conclusion. Hungary, the authors write, "remains a critical WNV transmission hub in Central Europe with established endemicity of multiple lineage 2 clades."

How this frames 2026

The 2026 European WNV season opened with the smallest opening tally in years. ECDC's weekly bulletin, produced on 26 June 2026 with data to 24 June, reports just two countries and three human cases: Italy, with two cases in the provinces of Caserta (Campania) and Firenze (Toscana), and North Macedonia, with one case in the Vardar region. There are no deaths. There are no new countries. There are no new areas. The W25 bulletin (data to 17 June) and the W26 bulletin (data to 24 June) sit seven calendar days apart and report identical totals. The W26 Communicable Disease Threats Report, published the same day, carries the season's institutional framing: "seasonal weather conditions are currently favourable for mosquito-borne transmission," with more cases expected across the coming weeks.

That framing is now read differently in light of the Nagy paper. Hungary's 2024 peak fell in late August and the first week of September, so a quiet June for Hungary is exactly what the phylogeography predicts. The 2025 Italian season finished at 779 cases and 72 deaths across nine regions, a case fatality of 9.2 percent. The 2026 European signal so far is in Italy and North Macedonia, with the Balkans, Hungary's southeast corridor, already represented through North Macedonia's Vardar case.

The structural question for 2026 is whether Hungary joins the tally in late summer. The Nagy analysis makes clear that the country has not lost its endemic status. The reservoir is in the Culex pipiens populations of the Great Plain, in the migratory birds that rest there, and in the lineage-2 viral diversity that has now been continuously circulating in Hungary for over two decades.

What the land-cover picture adds

A separate 2026 paper, by Riccetti and colleagues at the European Commission's Joint Research Centre, analyses WNV incidence across European provinces from 2005 to 2019 using spatial regression. Shrubland cover is the strongest and most spatially consistent positive predictor of human WNV incidence; forest cover is generally negative; urban and cropland have weaker, regionally variable effects. Warm summer temperatures and seasonal moisture balance are the dominant climatic predictors. Hungary's Great Plain counties sit precisely in the mosaic land cover the Riccetti analysis flags as most WNV-supportive: open agricultural land, riparian shrubland along the Danube and Tisza rivers, and scattered urban settlements.

The two papers together, genomic phylogeography on one side, pan-European land-cover spatial regression on the other, give the clearest institutional picture yet of where European WNV transmission is structurally supported. Hungary sits at the centre of both.

What to watch across the rest of the 2026 season

The next three ECDC bulletins, W27 (data to 1 July 2026, expected today or Friday 3 July), W28 (data to 8 July), and W29 (data to 15 July), are the season's first real expansion test. The 2025 baseline points to Greece, Romania, Hungary, Serbia and Spain as the most likely next countries to report. Hungary's corridor structure makes a late-summer 2026 case in Fejér, Bács-Kiskun, Csongrád-Csanád or Budapest itself the single highest-probability event in the European WNV calendar.

The Culex pipiens ecology around Budapest and the Great Plain has not changed; the viral diversity in the local bird populations has not been disrupted; and the 2024 strain is part of an endemic lineage-2 reservoir, not a one-off introduction. The 2026 European WNV season is about to test the structural prediction that Hungary remains the continent's persistent hub.

For travellers and residents in the Hungarian WNV belt, Budapest, the Great Plain, the Danube bend, the operative advice has not changed in a decade: cover up at dusk and dawn when Culex pipiens is most active, use a proven repellent on exposed skin, empty standing water weekly from gardens and balconies, and sleep under treated netting or in screened rooms in rural and peri-urban areas.

What we know

• Hungary reported 113 human WNV cases in 2024-111 autochthonous, 2 imported, a 3.7-fold increase on 2023, with incidence rising from 0.31 to 1.16 per 100,000 population. Nagy A et al., Euro Surveill 2026;31(16):2500785 (PMID 42141881)
• 92 percent (104 of 113) presented with neuroinvasive disease; nine patients died, for a case fatality ratio of 7.9 percent. Nagy A et al., Euro Surveill 2026;31(16):2500785
• All 55 sequenced strains (38 humans, 15 birds, 2 Culex pipiens mosquito pools) were WNV lineage 2; Hungarian viral diversity sits in 6 of 8 major European clades. Nagy A et al., Euro Surveill 2026;31(16):2500785
• Phylogeographic analysis identified two persistent viral corridors out of Hungary: westward along the Danube and southeastward into the Balkans, with bidirectional flow and northward expansion as a structural feature. Nagy A et al., Euro Surveill 2026;31(16):2500785
• ECDC's W26 weekly (data to 24 June 2026) and W25 weekly (data to 17 June 2026) both report identical 2026 totals: two countries, three cases, three areas, Italy (Caserta and Firenze) and North Macedonia (Vardar); no deaths. ECDC WNV weekly; ECDC W26 CDTR

Sources cited

1. Nagy A, Erdélyi K, Molnár Z, Bagóné Lőrincz R, Nagy O, Koroknai A, Csonka N, Kerényi K, Forgách P, Horváth E, Soltész Z, Nagy G, Takács M, Barcsay E, Szomor K, Tóth GE, Cadar D. Hungary as a source of West Nile virus diversity and spread in Europe: insights from the 2024 transmission season. Euro Surveill 2026;31(16):2500785. DOI: 10.2807/1560-7917.ES.2026.31.16.2500785. PMID 42141881; PMCID PMC13109698. https://pubmed.ncbi.nlm.nih.gov/42141881/
2. European Centre for Disease Prevention and Control, West Nile virus infection weekly bulletin, data as of 24 June 2026, produced 26 June 2026. https://wnv-weekly.ecdc.europa.eu/
3. European Centre for Disease Prevention and Control, Communicable Disease Threats Report, 19-26 June 2026, Week 26, published 26 June 2026. https://www.ecdc.europa.eu/en/publications-data/communicable-disease-threats-report-19-26-june-2026-week-26
4. Riccetti N, Cescatti A, Ciscar JC, Dubois G, Fanelli A, Figuerola J, Ibarreta D, Szewczyk W, Massaro E. Spatial role of land cover on West Nile virus disease in Europe. iScience 2026;29(6):115754. DOI: 10.1016/j.isci.2026.115754. PMID 42317728; PMCID PMC13273564. https://pubmed.ncbi.nlm.nih.gov/42317728/
5. European Centre for Disease Prevention and Control, Surveillance Atlas of Infectious Diseases: West Nile virus infection, current season (2026). https://www.ecdc.europa.eu/en/west-nile-virus-infection/surveillance-and-disease-data
6. Santé publique France, Bilan annuel 2025, Surveillance des arboviroses en France hexagonale, published 6 May 2026. https://www.santepubliquefrance.fr/