Europe is facing one of the worst waves of bird flu in recent years. Between September and November 2025, recorded cases reached unprecedented levels for this time of year, with thousands of outbreaks among wild and domestic birds. And, according to experts, the situation is destined to persist in the coming weeks.
An unprecedented epidemic among wild birds
The data released by the European Food Safety Authority (EFSA), the European Center for Disease Prevention and Control (ECDC) and the EU reference laboratory are clear: between 6 September and 28 November 2025, 2,454 outbreaks were reported in wild birds in 29 European countries (2,896 if farms are also considered). This is the highest number ever recorded at this time of year since 2016 and is therefore an unprecedented epidemic.
Waterfowl such as ducks, geese and swans have been particularly affected by highly pathogenic avian influenza (HPAI) type A(H5N1). The situation of common cranes was particularly dramatic, as they suffered episodes of mass mortality along their migratory routes across the European continent.
The causes of the surge in cases
Scientists have identified two possible explanations for this sudden escalation. The first concerns the lack of pre-existing immunity in wild bird populations, which therefore find themselves vulnerable to a recent variant of the virus. The second hypothesis calls into question the increased transmissibility of this specific HPAI A(H5N1) genotype, already present in the area but now becoming more aggressive.
Unfortunately, experts’ forecasts are not reassuring in the short term: the levels of circulation of the virus in wild birds will remain high in the coming weeks. Only towards the end of winter should we see a significant drop in infections.
Avian flu on farms
The spread of the virus in poultry farms was equally worrying, with 442 outbreaks recorded among domestic birds during the 3 months indicated above. The main route of infection was indirect contact with wild birds, favored by massive environmental contamination in the areas surrounding the farms.
Turkeys proved to be the most vulnerable species, while the new outbreaks that emerged among vaccinated ducks are attracting particular attention, a sign that the protection provided by vaccines may not be total. Environmental factors such as humidity and weather conditions have contributed to exacerbating the situation, creating ideal conditions for the transmission of the pathogen.
Faced with this scenario, experts have issued clear indications for breeders. The first recommendation is to house domestic birds in protected areas, especially where the virus is actively circulating among wild birds or where mass mortality incidents have occurred.
Rigorous biosecurity is also necessary and represents the first line of defense: access controls, constant disinfection, separation between clean and contaminated areas. Finally, strengthened surveillance is equally crucial to promptly detect new outbreaks and intervene before the infection spreads to other animals.
Cases are increasing among carnivorous mammals
Bird flu does not even spare mammals. During the period analyzed there was a slight increase in cases detected in wild carnivores, in particular foxes, directly related to the high circulation of the virus in wild birds.
After a long period without reports, the virus has also reappeared in domestic cats in two European countries. The animals probably became infected through direct or indirect contact with wild birds. Fortunately, no evidence of transmission through contaminated raw pet food has emerged, but caution remains a must.
To protect their pets, experts recommend that owners avoid feeding raw meat or other uncooked animal products. In areas where circulation of the HPAI virus is particularly high, it is advisable to keep pets indoors or at least on a leash during walks, to minimize exposure to potential sources of infection.
And the risks for humans?
In terms of transmission to humans, 19 cases of avian influenza virus infection were reported between 9 September and 28 November 2025 in four countries: Cambodia – three A(H5N1) cases, with one death; China – 14 A(H9N2) cases; Mexico – one A(H5N2) case and United States with one fatal A(H5N5) case.
All cases of A(H5) had one common feature: exposure to poultry or avian environments before the onset of the disease. However, no cases of person-to-person transmission have been documented, an element that contributes to keeping the alert level low.
Despite the widespread circulation of avian influenza viruses in animal populations, human infections therefore remain rare. As ECDC writes:
The risk posed by avian influenza A(H5N1) clade 2.3.4.4b viruses currently circulating in Europe remains low for the general population in the European Union/European Economic Area and low-moderate for those exposed, for occupational or other reasons, to infected animals or contaminated environments.
The avian influenza situation in Europe will continue to require attention and vigilance in the coming months. The key to containing the epidemic lies in an integrated approach that combines surveillance, biosecurity on farms and protection of domestic animals.
Only with the end of winter and the change in environmental conditions can we hope for a significant reduction in the circulation of the virus. In the meantime, constant monitoring of the situation and prompt intervention remain the most effective weapons to protect both animals and people.
Sources: Efsa / ECDC
