West Nile virus infections have been reported in five European countries as the 2026 transmission season gathers pace, with health authorities warning that mosquito activity and weather conditions could lead to further spread.
Locally acquired cases have been recorded in Greece, Italy, Spain, Romania and North Macedonia, according to the latest data from the European Centre for Disease Prevention and Control.
Greece has reported 21 locally transmitted infections since the start of its 2026 surveillance season through July 22, the country’s National Public Health Organisation said. Twenty patients developed neurological complications affecting the central nervous system, including encephalitis, meningitis or acute flaccid paralysis. One patient experienced mild symptoms.
No deaths have been recorded in Greece so far, while 13 patients remain hospitalised. Fourteen new locally acquired infections were reported during the latest week.
A separate case involving a person with a complex travel history was also identified, but authorities have not yet determined the likely country of exposure. That case was excluded from Greece’s local epidemiological analysis.
Across Europe and neighbouring areas, 33 locally transmitted cases had been reported in five countries in data submitted to the ECDC through July 15.
Italy recorded the largest number, with 20 cases spread across 16 areas. Novara reported three cases, while Cremona and Verona each recorded two. Other affected locations include Milan, Florence, Naples, Padua, Modena and Ferrara.
North Macedonia reported two cases in the Skopje and Vardar regions. Romania recorded infections in Argeș and Suceava, while Spain reported cases in Alicante and Seville.
The ECDC data also show how quickly the virus has expanded geographically. In Italy, 11 of the 16 affected areas were added during the latest reporting week.
In Greece, most cases have been reported in the Attica region, with infections recorded across several municipalities. Two additional cases were identified outside Attica, in the Regional Unit of Larissa and the Municipality of Palamas.
Greek authorities have also designated several municipalities as high-risk areas despite no human infections being reported there so far. The assessments were based on epidemiological and geographical factors, as well as proximity to areas where transmission has already been detected.
EODY said the repeated appearance of human cases in Greece almost every year since 2010 shows that West Nile virus has become established in the country.
The virus is carried by mosquitoes and can circulate through populations of wild birds, which act as its natural reservoir. Transmission is influenced by temperature, rainfall, mosquito numbers and bird movements.
Health authorities are urging people across affected regions to use mosquito protection measures, including repellents, suitable clothing and screens, as it remains difficult to predict exactly where new infections will appear during the summer season.
