Italy opens 2026 West Nile season: Caserta and Firenze report the first mainland EU cases

Italy has reported its first locally-acquired human cases of West Nile virus for the 2026 season. The European Centre for Disease Prevention and Control's Communicable Disease Threats Report for Week 25 — released on 18 June 2026, with data complete to 17 June — confirms two autochthonous cases, in two separate parts of the country: one in Caserta, in the southern region of Campania, and one in Firenze (Florence), in central Toscana. No deaths have been reported.

These are the first 2026 West Nile cases anywhere in mainland EU. The earliest human case of the season in the wider European Region had already been logged in the Vardar region of North Macedonia — a single case, in an EU-candidate country that sits inside ECDC's surveillance for the EU/EEA and its neighbourhood, not an EU member. With Caserta and Firenze, Italy now joins North Macedonia as a 2026 West Nile country, and becomes the first EU member state to report.

This is the development the season had been waiting on. Here is what the numbers say, what the two-city pattern does and does not tell us, and what it means for households now.

What the numbers say

The 2026 figures are deliberately small: two cases, two locations, zero deaths. That is the whole of Italy's locally-acquired West Nile count for the year so far, as of ECDC's 17 June data cut-off.

The reason those two cases carry weight is the line they open from. In 2025, Italy was the largest single-country West Nile burden in the entire EU/EEA: 779 confirmed human cases and 72 deaths, a case-fatality rate of roughly 9.2%. That season concentrated in Lombardia, Veneto and Emilia-Romagna, with a further cluster in Lazio across July and August. Across the EU/EEA as a whole, West Nile killed 97 people in 2025 (ECDC).

A note on rigour, because it matters for how you read any single figure here: the 779 is ECDC's end-of-season, cross-country total. Italy's own integrated arbovirus surveillance — run by the Istituto Superiore di Sanità (ISS) under the national arbovirus plan (Piano Nazionale Arbovirosi), which tracks West Nile alongside Usutu virus — recorded 773 confirmed cases in its last integrated bulletin of the 2025 season (n. 16, 30 October 2025). The small gap reflects cases added after ISS paused weekly publishing, not a contradiction. The two authorities are measuring the same outbreak with slightly different cut-offs. We cite both rather than smoothing it over.

The point is not the decimal places. The point is that 2026 starts from a country that, twelve months ago, carried the heaviest West Nile season in the bloc — and that this year's first two cases are simply the front edge of a window that, by ECDC's own surveillance calendar, runs into late October.

Two cities, not one cluster

The detail worth pausing on is geography. Caserta and Firenze are not neighbours. Campania is in the south; Toscana is in the centre of the country. The two cases are several hundred kilometres apart.

That is worth stating plainly, and then not over-reading. Two distant cases are not a single local cluster — they are two independent points of local transmission, in two different regional mosquito populations, detected in the same reporting week. What it tells us is that the conditions for Culex pipiens — the common house mosquito that carries West Nile — to pick up and pass on the virus are present across more than one part of Italy this June. What it does not tell us is how large either focus will become, or whether more regions will follow. A two-point map is a starting condition, not a forecast.

ISS's integrated surveillance is in force and publishing weekly bulletins, which is the mechanism by which any widening will show up early. The honest read for now: the season has opened in two places at once, and the next few weeks of bulletins will say whether it stays there.

Why the barrier is the layer that holds

This is where our editorial posture is settled, and West Nile illustrates it cleanly. There is no widely deployed West Nile vaccine for the general public, and there is no specific antiviral treatment. The defences that actually exist are the boring ones: keep the mosquito away from the person.

Mosticare's position — argued at length in our season-opening piece — is barriers-first. A physical barrier, a window screen or a net built to WHO standards, is the layer that does not degrade. It cannot be conditioned around the way a repellent can, it does not wait for a vaccine restart date, and it does not need reapplying every few hours. Chemicals and any future vaccines are additional layers with their own place; they are not the dependable one. The dependable layer is the one that physically excludes the insect from the room you sleep in.

Underneath all of this sits the mechanism researchers keep returning to: transmission capacity for West Nile and dengue rises by roughly 20% for every additional degree Celsius. That is the quiet reason a season opens earlier, and in more places, than the old maps assumed — and the reason the barrier matters more each year, not less.

What to do at home

For households in or travelling to affected areas this summer, the measured response is unglamorous and effective:

1. Empty standing water on your property every week — planters, pet bowls, blocked gutters, drain trays, anything that holds a few days of rain. Most breeding happens within metres of where people are bitten.
2. Fit insect screens on bedroom and kitchen windows, and sleep under a net if you are in a transmission zone. This is the layer that holds.
3. Treat aerosol sprays and plug-in diffusers as the weakest layer, not the first — useful at the margin, unreliable as your main defence.
4. See a GP if you develop fever with headache and joint or muscle pain within about three weeks of being in an affected area, and mention where you have been.

This is general information, not a diagnosis. Most West Nile infections are mild or symptomless; a small minority become serious, which is exactly why awareness and the physical barrier matter rather than alarm.

What we are watching

Three questions will shape the next fortnight. Whether Caserta or Firenze widen into larger local foci. Whether other EU/EEA countries — several of which had resumed enhanced national surveillance heading into the season — report their own first 2026 West Nile cases. And what the next ECDC weekly bulletins show beyond Italy and North Macedonia.

We will track each of those here, and on the Mosticare Threat Map, which carries the live country-by-country surveillance picture. The data room holds the machine-readable incidence feed, now refreshed to reflect Week 25, and the West Nile virus page keeps the topic view current.

The season has opened in two Italian cities. The line it opens from is last year's. We will not let it pass quietly.