Italy Reports 432 West Nile Virus Cases, 17 Deaths

Cases of mosquito-borne West Nile virus are rising in Italy. So far this year, 432 people have tested positive for the virus, with 17 deaths reported. More than 100 new cases were detected within a week, prompting health authorities to step up vigilance over the situation.

The latest report from Italy’s National Institute of Health (ISS), released on Thursday (August 27), provided the figures. According to the report, 223 of the 432 patients developed neuroinvasive disease affecting the nervous system. Another 144 patients had fever symptoms, while the virus was also detected in 63 asymptomatic blood donors.

According to ISS data, West Nile virus has spread across 66 provinces in 17 regions of Italy this year. Lombardy has recorded the highest number of cases at 114, followed by Veneto with 74, Lazio with 63, Piedmont with 60 and Emilia-Romagna with 42. This indicates that the virus is circulating across a wide area of the country rather than being confined to specific regions.

The current case-fatality rate among patients with neuroinvasive disease is 7.2 percent, down from 13.9 percent during the same period last year. Although the total number of cases is slightly higher than at the same point last year, the number of deaths is lower. At the same time in 2025, 27 deaths were reported among 430 cases.

Meanwhile, evidence of increased virus circulation among mosquitoes has been found in Italy’s Veneto and Friuli-Venezia Giulia regions. Local mosquito surveillance tested around 168,000 mosquitoes and identified 73 positive mosquito pools. The virus detection rate was 4 percent in Veneto and 0.5 percent in Friuli.

The main vectors of West Nile virus are mosquitoes of the Culex genus. Wild birds generally serve as the natural reservoir of the virus, which can spread to humans and horses through the bites of infected mosquitoes. The virus is not generally transmitted through direct human-to-human contact. However, rare cases of transmission through blood transfusion, organ transplantation and from mother to child during pregnancy have been documented.

According to surveillance by Italian health authorities, the risk of West Nile virus infection is higher during summer and autumn. The country is therefore carrying out coordinated surveillance to control mosquito populations, monitor affected areas and ensure the safety of blood and organ donations. The ISS said infection data are being updated weekly based on the evolving situation.