Italy’s West Nile Surge Signals a Warming Europe

Rome – It’s hard to miss the hum of a summer night in Italy, but what’s often invisible is the buzzing of millions of mosquitoes that thrive in the heat. Scientists at the Italian National Institute of Health (ISS) are now warning that a hotter, longer summer is letting these pests travel farther and stay active longer, spreading West Nile virus (WNV) across a broader swath of the country.

“When the mercury climbs, mosquitoes reproduce faster and the virus lingers longer in the environment,” explained Antonino Bella, a senior researcher in ISS’s Infectious Diseases Department. “That means a higher chance that an infected mosquito will bite a person, and the season can stretch into November.”

So far this year, more than 650 Italians have tested positive for West Nile – about half of all cases reported in Europe for 2026. Most infections are mild or asymptomatic, but a small slice, especially older adults or those with pre‑existing health issues, can develop serious neurological complications.

The surge isn’t entirely new. Since 2020, Italy has classified West Nile as endemic, with annual spikes every summer and early autumn. Yet the current climate patterns are nudging the virus into provinces that previously saw few, if any, cases. Researchers point to the expanding geographical footprint as a clear sign of climate‑driven change.

Italy’s meticulous surveillance – tracking mosquito populations, wild birds, blood donors and human patients – gives it a clearer picture than many of its neighbours. That thoroughness attracted a delegation from Belgium’s public‑health institute in May, keen to learn how the Italian system works.

Further north, the Netherlands has recorded its first locally acquired West Nile infections since 2020, along with several fatalities, prompting alarm bells at its public‑health agency. “Warmer weather lengthens the replication window for both the virus and its vectors,” said Marc‑Alain Widdowson, head of the WHO Europe’s Pandemic Threats Division. “Climate change isn’t the sole cause, but it certainly stretches the mosquito season and improves viral survival.”

Widdowson also highlighted other ecological factors: dwindling biodiversity and altered land use may favor bird species that act as efficient virus reservoirs, while a richer mosquito population simply provides more opportunities for transmission.

Europe’s broader battle with invasive mosquito species adds another layer of complexity. The European Centre for Disease Prevention and Control (ECDC) warned earlier this year that heatwaves, floods and longer summers are creating a hospitable playground for Aedes albopictus and Aedes aegypti. The latter, notorious for spreading dengue, Zika and yellow fever, has been established in Cyprus since 2022 and could hop to other nations. A decade ago, Aedes albopictus was found in eight EU countries; this year it’s entrenched in 13, covering 337 regions.

For now, Italy’s health officials stress vigilance: continued monitoring, public awareness about mosquito protection, and rapid response to outbreaks. The message is clear – as Europe warms, the tiny winged carriers of West Nile are poised to travel farther, linger longer, and remind us that climate and health are inseparably linked.