Cases of West Nile virus infection have been reported in 12 European countries so far this year, according to the European Centre for Disease Prevention and Control (ECDC). The agency has called on European countries to strengthen mosquito-control measures to limit the spread of the virus.
Local transmission has been recorded in 99 regions across Albania, Austria, France, Germany, Greece, Italy, Kosovo, the Netherlands, North Macedonia, Romania, Serbia and Spain. Italy has reported the highest number of cases, with 311 infections, followed by Greece with 157. In 21 regions, the virus was detected for the first time.
By comparison, during the same period in August 2025, locally acquired cases had been reported in 67 regions across nine European countries.
The ECDC says the growing spread of West Nile virus, along with the expansion of invasive mosquito species, highlights the need for stronger mosquito-control programs. Celine Gossner, head of the agency's unit for food-, water- and vector-borne diseases, said effective prevention requires monitoring mosquito populations, raising public awareness and implementing targeted control measures while taking environmental impact into account.
Most human infections in Europe occur from late spring through autumn, with transmission typically peaking between July and September.
West Nile virus is primarily transmitted by mosquitoes of the Culex genus. In most infected people, the illness causes mild symptoms similar to influenza. In severe cases, however, patients may develop high fever, tremors, coma, meningitis and encephalitis, a potentially life-threatening inflammation of the brain.
There is currently no specific treatment for West Nile virus, and no vaccine for humans has been approved. Patients with severe disease receive supportive medical care.
Meanwhile, the Asian tiger mosquito (Aedes albopictus), which can transmit dengue and chikungunya viruses, continues to expand its range in Europe. According to the ECDC, the species has now become established in 16 European countries—twice as many as 12 years ago.
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