West Nile virus: ECDC counts 625 autochthonous cases in twelve European countries

The European Centre for Disease Prevention and Control updates the count of West Nile virus infections acquired in European territory every week. As of August 21, 2026, the autochthonous cases reported total 625, distributed across twelve countries.

Country	Autochthonous cases
Italy	311
Greece	157
Spain	63
North Macedonia	37
Romania	28
France	17
Serbia	6
Netherlands	2
Albania, Austria, Germany, Kosovo	1 each

In the reference week, 21 areas were reported as affected for the first time this season. This is the indicator describing geographic extent, distinct from the one describing intensity: a new area means that virus circulation was detected where it had not been recorded in previous weeks.

The trend of detections

Comparing ECDC publications over the span of a few weeks shows the seasonal progression. In the joint monthly ECDC-EFSA report, as of August 5, 2026 there were 245 autochthonous cases in seven countries, with onset dates ranging from May 12 to August 1. On August 20, on the occasion of World Mosquito Day, ECDC reported 429 autochthonous cases in nine countries as of August 13, also noting six European regions with autochthonous infections for the first time ever.

A methodological caveat is necessary: the three figures cannot be compared as if they were homogeneous measurements of the same quantity. They come from surveys with different update dates and reflect cases reported by national surveillance systems, which record diagnosed and communicated infections, not the total number of people infected. Variations from one week to another also depend on reporting times.

The vector

ECDC reports that the tiger mosquito (Aedes albopictus) is now permanently established in 16 European countries, double the figure from twelve years ago. This is entomological distribution data, not a transmission count: it describes where the species is stably present, not how many cases it causes.

On response capabilities, Céline Gossner, an ECDC expert, stated: “Europe must upgrade its mosquito control capacity” (transl. from English). This is a position of the European agency, reported as such.

What the agencies expect

ECDC and EFSA expect further human cases in the coming weeks: transmission, they recall, normally peaks between August and September. The forecast concerns the seasonal trend as a whole across the countries under surveillance, not individual areas.

The documents underlying this article do not report the number of deaths, the distribution by clinical form, nor the breakdown by region within individual countries. The next verifiable data point is ECDC’s weekly update, which will move the count from August 21 to the following week.

Sources: ECDC, West Nile weekly surveillance; ECDC, press release for World Mosquito Day 2026; EFSA Journal, joint ECDC-EFSA monthly report; Medical Xpress.