West Nile virus reaches 12 European countries as cases rise to 311 in Italy and 157 in Greece

Geographic expansion across 12 European countries

Public health authorities across Europe are monitoring the spread of West Nile virus after infections were detected in 12 countries during the 2026 transmission season. Data compiled by the European Centre for Disease Prevention and Control (ECDC) records infections in 99 separate regions, indicating a broader geographic distribution than in the corresponding period of 2025, when 67 regions across nine countries reported cases. The 12 countries with documented transmission are Albania, Austria, France, Germany, Greece, Italy, Kosovo, the Netherlands, North Macedonia, Romania, Serbia, and Spain. In 21 of the 99 affected regions, local health authorities identified West Nile virus infections for the first time. Italy documented the highest transmission volume across Europe with 311 cases, while Greece reported the second highest count at 157 infections.

National infection figures and county breakdown in Romania

Romania recorded the third-highest number of affected administrative zones among the 12 European countries, behind Italy and Greece. Figures released by the National Centre for Surveillance and Control of Communicable Diseases within the National Institute of Public Health (INSP) show 34 cases reported between 3 June and 20 August 2026. Of these 34 cases, 26 are laboratory-confirmed and eight are classified as probable. Two infected patients died, both of whom were elderly individuals with existing comorbidities. The municipality of Bucharest registered the highest concentration of infections, followed by Călărași and Giurgiu counties. Probable exposure locations span Bucharest alongside 14 counties: Argeș, Bihor, Botoșani, Călărași, Cluj, Giurgiu, Harghita, Ialomița, Iași, Ilfov, Mureș, Satu Mare, Suceava, and Vaslui.

Demographic distribution and clinical characteristics

Infection data from Romania indicates that older age brackets represent the majority of reported cases. Patients aged 50 to 59 years and those aged 70 to 79 years each account for seven cases, followed by six cases among patients aged 80 years and older. Four cases each were recorded in the 40 to 49 age bracket and the 60 to 69 age bracket. West Nile virus transmits to humans primarily through bites from infected mosquitoes. While many infections result in mild, flu-like symptoms, severe presentations lead to neurological complications such as meningitis or coma. Public health agencies point out that there is no specific antiviral therapy or treatment for West Nile virus infection, meaning clinical interventions are limited to supportive care for affected patients.

Vector control measures and seasonal transmission patterns

In Europe, the transmission cycle of West Nile virus runs from summer into autumn, with infection rates typically peaking in August and early September. The ECDC stated that additional cases may emerge before the end of the 2026 transmission season. The European agency linked the geographic expansion of infections to the ongoing spread of invasive mosquito species across the continent. Céline Gossner, an ECDC expert in foodborne, waterborne, and vector-borne diseases and zoonoses, called for a coordinated European strategy to counter the transmission. Recommended interventions include regular surveillance of mosquito populations, active community involvement, and targeted vector control programs integrated with environmental impact evaluations.