West Nile virus is no longer a rare or unexpected disease in Europe. Over the past ten years, it has become a regular summer health concern in many parts of the continent, especially in southern, central, and eastern Europe. Data collected by the European Centre for Disease Prevention and Control, show that the virus now appears almost every year in several countries.

At first, cases were reported only occasionally, but that has changed. Countries such as Italy, Greece, Spain, and Hungary have seen repeated outbreaks, which suggests the virus has become established rather than appearing by chance. In many of these areas, people and health authorities now expect West Nile virus to return each summer.

The number of infections can vary widely from one year to the next. Some seasons pass with relatively few cases, while others see large outbreaks. In 2022 and again in 2024, Europe recorded more than a thousand locally acquired human infections, and dozens of people died in each of those years. These spikes show that while many infections are mild, the virus can cause serious illness, especially in older people or those with existing health problems.

West Nile virus spreads mainly through mosquito bites, and cases usually rise during the warmer months when mosquitoes are most active. Most infections are reported between late spring and early autumn. Hot weather and long summers help mosquitoes breed and spread the virus more easily, which is why outbreaks tend to be seasonal.

ECDC data also show that the virus has gradually spread to more areas. Places that once reported only a few cases now see infections almost every year, and some countries have recorded their largest outbreaks in recent seasons. This growing presence has raised concerns that changing environmental conditions may be making it easier for the virus to survive and spread.

Health authorities across Europe closely monitor the situation each year. The ECDC coordinates reporting between countries and publishes regular updates during the mosquito season. This information helps governments take action, such as controlling mosquito populations, screening blood donations, and advising the public on how to avoid mosquito bites.

Even with these efforts, West Nile virus is likely to remain a recurring summer issue in Europe. Experts say continued monitoring and public awareness will be key to reducing its impact in the years ahead.