Por Renan Filho · 2026-10-21
**Lead**
Europe has recorded its highest ever number of West Nile virus cases this year, according to the European Centre for Disease Prevention and Control (ECDC). The disease, transmitted by infected mosquitoes, has spread more aggressively than in previous seasons, with multiple countries reporting outbreaks well into autumn. Health authorities across the continent are urging vigilance as climate conditions continue to favour the mosquito vectors responsible for transmission.
**Context**
West Nile virus is a flavivirus commonly found in Africa, Europe, the Middle East, North America and West Asia. It is primarily spread to humans through the bite of infected Culex mosquitoes. In most cases, the infection causes mild, flu-like symptoms, but it can occasionally lead to severe neurological disease such as encephalitis or meningitis, particularly in older adults or those with weakened immune systems. The virus has been present in Europe for decades, with seasonal outbreaks typically occurring from June to November. However, the current season has broken all previous records in terms of case numbers.
The ECDC’s latest epidemiological update indicates that the surge is concentrated in several southern and central European nations, including Italy, Greece, Spain, Serbia and Hungary. In Italy alone, regions such as Veneto and Emilia-Romagna have reported a sharp increase in locally acquired infections. Greece has also seen a significant rise, with cases appearing in areas that previously experienced only sporadic transmission. France, Germany and Austria have also reported a higher than usual number of human cases, along with an increase in confirmed infections among birds and horses, which act as sentinel species.
**Analysis**
This record-breaking season is believed to be driven by a combination of climatic factors. Warmer temperatures and prolonged periods of heat have extended the mosquito breeding season and increased the rate at which the virus multiplies inside the insects. This summer, much of Europe experienced intense heatwaves, with temperatures frequently exceeding 40°C in southern countries. Such conditions are known to accelerate the mosquito life cycle and boost the virus’s transmission potential. Furthermore, heavy rainfall in some regions created stagnant water bodies, ideal breeding grounds for mosquitoes, while droughts in other areas increased the use of water storage containers, which also serve as breeding sites.
The public health impact is considerable. Although the overall mortality rate remains low, a higher case load inevitably leads to more severe outcomes. Intensive care units in some affected regions have reported an increase in admissions for West Nile neuroinvasive disease. Blood transfusion services have had to implement enhanced screening protocols, as the virus can be transmitted through donated blood. Health ministries have ramped up vector control measures, including insecticide spraying, public awareness campaigns, and the promotion of personal protective measures such as mosquito repellents and bed nets.
Looking ahead, experts warn that without sustained efforts to address climate change and improve vector surveillance, Europe can expect more such record-breaking seasons. The ECDC has called for integrated surveillance systems that link human, animal and environmental data to detect early signals of viral activity. Additionally, vaccine development for West Nile virus remains in early stages; no licensed human vaccine is currently available in Europe. The reliance on preventive measures therefore places a heavy burden on public health systems and individual behaviour change.
**Sources**
European Centre for Disease Prevention and Control (ECDC) – West Nile virus seasonal surveillance reports, 2024. World Health Organisation (WHO) – Fact sheet on West Nile virus. National public health institutes of Italy, Greece, Spain, Serbia and Hungary – epidemiological bulletins.