Italy records 652 West Nile cases as the virus moves south and late into autumn

Italy has confirmed 652 locally acquired West Nile virus infections this transmission season, according to the European Centre for Disease Prevention and Control update covering data to 17 September. That is just under half of the 1,482 human cases reported across 16 European countries. Greece follows with 355. Spain has 114. Romania has 91.

The Istituto Superiore di Sanita had already counted 594 Italian cases by 9 September, including 306 neuroinvasive illnesses and 41 deaths, one of them imported. Antonino Bella, who tracks arboviruses at the ISS, told reporters this week that the 2026 totals are not out of line with recent summers. What has changed is the map and the calendar.

From the Po valley into the centre and south

West Nile has been treated as endemic in Italy since 2020. For years the load sat in Veneto, Emilia-Romagna, Lombardy and Piedmont, where rice fields, river basins and large bird roosts give Culex mosquitoes what they need. Massimo Ciccozzi, an epidemiologist at Campus Bio-Medico in Rome, said the 2026 season is defined by spread into central and southern regions that used to report little or nothing. ISS surveillance by late August had already found viral circulation in 66 provinces across 17 regions, including Campania, Puglia, Calabria, Sicily and Sardinia.

Padua, Milan and Rome sit at the top of the municipal counts published by Il Sole 24 Ore earlier this month: 50, 48 and 46 cases respectively at that snapshot. Latina, Turin, Oristano and Caserta were also on the list. Those last two names would have looked odd in a West Nile table ten years ago.

Why the season is longer

About 80 percent of infected people never feel ill. Most of the rest get a short fever. Severe neurological disease is uncommon and concentrated in older patients and people with other illnesses. Bella's warning is about mosquitoes, not a sudden change in the virus. Higher night temperatures help Culex breed later into the year. In some districts transmission now runs into November. Blood services already screen donors in affected provinces. That net will have to stay up longer if the first frost keeps arriving late.

ECDC's weekly map listed 180 affected areas in 16 countries as of 17 September, 19 of them newly reported in that week. Italy accounts for 65 of those areas. The Netherlands has passed two dozen human cases and several deaths, enough that a Belgian research team recently visited Italian labs to copy surveillance methods after Belgium recorded its own locally acquired infections.

Birds, horses and a quiet winter question

The virus spends most of its life in birds. Horses and humans are dead-end hosts. Italy reported early-season outbreaks in hooded crows and a golden eagle. France reported an outbreak in equids that began on 30 March. Those veterinary signals arrived before the human peak, which is how the system is supposed to work. The open question for 2027 is whether provinces that only lit up this August will start the next season earlier.

Italian local health agencies are repeating the same advice they issue every July: empty standing water, use repellent at dusk, keep window screens intact. None of that is new. The new fact is the geography. A virus that health ministries once filed under the Po valley now has a case list that includes Caserta and Oristano, and a season that no longer ends when August does.