Highly Pathogenic Avian Influenza: Europe on Edge Until the End of Winter

Between mid-September and the end of November, Europe saw a resurgence in cases of highly pathogenic avian influenza (HPAI H5) among both wild birds and poultry. In a joint analysis, the European Food Safety Authority (EFSA) and the European Center for Disease Prevention and Control (ECDC) warn that new outbreaks are likely through the end of winter, even though the risk to the public is considered low.  

An autumn wave of a magnitude not seen since 2016

According to this report, covering the period from September 6 to November 28, 2025, 2,896 detections of the HPAI H5 virus were reported in Europe across 29 countries, including 442 in poultry farms or among domestic birds and 2,454 among wild birds. Waterfowl (ducks, geese, swans) are the most affected, with, notably, episodes of mass mortality among gray cranes. Most cases are linked to a new variant of the H5N1 genotype already encountered in Europe, but which appears to be either more transmissible or to affect bird populations with little or no immunity.  

Farms Caught in the Crossfire of Migration

As in previous seasons, the virus “enters” poultry houses via wild birds, most often indirectly (through droppings, contaminated dust, or soiled water or feed). Turkey farms are particularly affected, but authorities are also reporting cases in flocks of ducks that had been vaccinated, a sign of high viral pressure. EFSA and the ECDC recommend that, in all areas where avian influenza is circulating among wild birds and where mass mortalities are observed, poultry should be kept under confinement, biosecurity measures should be strengthened (restricting access, changing clothing and footwear, protection of water sources and feed), and to intensify clinical and virological surveillance to detect any outbreak at the earliest stage.  

Foxes and Cats: Unintentional Sentinel Species

The intense circulation of the virus among the avifauna has also led to a slight increase in cases among mammals, particularly foxes, which become infected after ingesting infected birds. Even more concerning, the virus has once again been detected in domestic cats in two European countries, following several months without any reports. Here again, the most likely source remains direct contact with sick birds or their carcasses. Experts are reminding the public of a few safety precautions: avoid feeding pets raw meat or offal, and in areas where the virus is actively circulating, limit unsupervised outings for dogs and cats by keeping them indoors or on a leash.  

A Low but Closely Monitored Risk to Humans

In humans, the ECDC continues to assess the risk as “low” for the general population and “low to moderate” for exposed professionals (livestock farmers, veterinarians, slaughterhouse workers, and outbreak cleanup crews). No human-to-human transmission has been documented in Europe to date, although sporadic infections linked to close contact with infected poultry have been reported worldwide in recent months. European agencies nevertheless emphasize the importance of personal protective equipment in the field (masks, goggles, gloves) and of seasonal flu vaccination for exposed workers, which can reduce the risk of coinfection and thus of recombination between human and avian viruses.  

A Test for the European Response

This new outbreak of avian influenza comes as the H5N1 virus has already led, since 2021, to the culling of hundreds of millions of poultry worldwide, undermining the poultry industry and the agri-food market. In Europe, the 2025–2026 season represents a real-world test: a test of Member States’ ability to combine the vaccination of certain flocks, the temporary confinement of animals, enhanced biosecurity, and coordinated surveillance of wildlife. The models presented by EFSA predict that viral circulation will continue in wild bird populations over the coming weeks, with a decline expected only at the end of winter, depending on migration patterns and weather conditions. Until then, vigilance remains essential, both to protect livestock and to monitor the rare potential links between animal health and human health.