Avian influenza overview September–November 2025

The magnitude and geographical extent of these detections were unprecedented for this time of the year, particularly in wild birds. Large numbers of waterfowl were affected by the disease, and mass mortality of common cranes was observed along their migratory routes in Europe. Given the high levels of virus circulation in wild birds and the resulting high environmental contamination, most HPAI outbreaks in domestic birds were primary, with indirect contact with wild birds being the most likely source of infection. 

Among poultry species, turkeys were proportionally the most affected, and HPAI outbreaks were once again reported in vaccinated ducks. A slight increase in HPAI virus detections in mammals was noted among foxes and domestic cats in Europe, consistent with the increase in detections in wild birds. 

Between 9 September and 28 November 2025, 19 cases of avian influenza virus infection in humans, including two deaths, were reported in four countries: Cambodia (three A(H5N1) cases, one death), China (14 A(H9N2) cases), Mexico (one A(H5N2) case), and United States of America (USA) (one fatal A(H5N5) case). All of the A(H5) human cases (n = 5/5) reported exposure to poultry or a poultry environment prior to detection or onset of illness. The current high level of avian influenza virus in bird populations increases the risk of human exposure to infected animals. Nevertheless, given the widespread circulation of avian influenza viruses in animal populations, human infections remain rare.

No instances of human-to-human transmission were documented during the reporting period. The risk posed by avian A(H5N1) clade 2.3.4.4b influenza viruses currently circulating in Europe remains low for the general public in the European Union/European Economic Area and low-to-moderate for those occupationally or otherwise exposed to infected animals or contaminated environments.