Key Points

• Since August 2025, there has been a constant circulation of highly pathogenic avian influenza viruses of subtype A(H5N1) from clade 2.3.4.4b among wild birds in Europe, including France; this circulation became very intense starting in mid-October 2025.

• Mass mortality has been observed since mid-October in the common crane population along their southward migration route in Germany, Belgium, France, and Spain. In France, more than 10,000 carcasses of infected cranes had been recorded as of November 10, 2025, across numerous departments along the northeast-southwest diagonal. The epizootic risk level for highly pathogenic avian influenza has been raised to “High” across the entire metropolitan territory, and preventive and biosecurity measures for poultry farms have been strengthened.

• Given this situation, there is a high risk of HPAI introduction into facilities housing wild or domestic birds.

• Increased risk, though difficult to quantify based on current knowledge:

  • Contamination of the environment and other species of wild and domestic birds and mammals exposed to carcasses: wild boars, wild carnivores (foxes) and domestic carnivores (cats, dogs), as well as ruminants with access to pastures;

  • Human exposure to infected animals.

• From the start of the 2025–2026 surveillance season (August 1, 2025) through November 10, 2025, 16 outbreaks occurred in poultry farms and 7 in backyard flocks or other establishments keeping birds in France.

• Plausible impact of mandatory duck vaccination on reducing the scale of the A(H5N1) clade 2.3.4.4b epizootic in poultry farms observed in France since the 2023-2024 winter season.

• No cases of human infection with avian influenza virus have been detected in France to date.

• Since 2022 and as of October 6, 2025, 129 human cases caused by the A(H5N1) virus have been reported by 13 countries and attributed to 3 different clades, with no human-to-human transmission detected.

• Low frequency of detection of markers of adaptation to humans in A(H5N1) viruses of clade 2.3.4.4b in wild birds.

• Based on currently available data, the risk associated with avian influenza viruses of subtype A(H5N1) from clade 2.3.4.4b is assessed as low for the general population and low to moderate for individuals regularly exposed.