West Nile virus spreads across 12 European countries as health agencies urge mosquito control

West Nile virus has taken hold across twelve European nations this summer, marking a significant expansion of a disease that most of the continent had managed to keep at bay. The Stockholm-based European Centre for Disease Prevention and Control reported the outbreak on Friday, noting that infections have surfaced in ninety-nine separate regions—a sharp jump from the sixty-seven regions across nine countries that had reported cases during the same window last August.

Italy and Greece have borne the heaviest burden. Italy alone has recorded three hundred and eleven cases, while Greece has confirmed one hundred and fifty-seven. What makes this year's spread particularly concerning is that twenty-one regions are reporting West Nile virus for the first time, suggesting the disease is establishing itself in areas where it had never taken root before. The twelve affected countries form a band across the continent: Albania, Austria, France, Germany, Greece, Italy, Kosovo, the Netherlands, North Macedonia, Romania, Serbia, and Spain.

The virus itself is deceptive in its presentation. Most people who contract it experience symptoms resembling ordinary flu—fever, fatigue, body aches. But in a subset of cases, the disease turns severe. Infected individuals can develop tremors, high fevers, and loss of consciousness. In the worst scenarios, the virus triggers encephalitis, a potentially fatal swelling of brain tissue, or meningitis, inflammation of the membranes surrounding the brain and spinal cord. There is no vaccine to prevent infection and no specific antiviral drug to treat it. Doctors can only manage symptoms and provide supportive care in hospital settings for those who become critically ill.

The virus spreads through the bite of Culex mosquitoes, which are already widespread across Europe. Transmission peaks between July and September, during the height of mosquito season, which runs from late spring through autumn. Celine Gossner, who heads the ECDC's division overseeing food-, water-, and vector-borne diseases, called the expansion a wake-up call. She emphasized that Europe must strengthen its capacity to control mosquito populations through coordinated effort—combining surveillance, public engagement, and targeted interventions that account for environmental consequences.

The challenge extends beyond West Nile virus alone. The Asian tiger mosquito, an invasive species capable of transmitting dengue and chikungunya, has now established itself in sixteen European countries. That number has doubled over the past twelve years, indicating that the continent's mosquito ecology is shifting in ways that favor disease transmission. The Culex mosquitoes that carry West Nile virus are already entrenched; the arrival and spread of new invasive species compounds the problem. Without coordinated action across borders, health officials warn, the geographic footprint of these diseases will continue to expand, and the regions where they circulate will keep growing.