Avian Influenza A (H5N1) Emergence Unit
Status: active - level 1
Last updated on 31 October 2025
Key facts
- Avian influenza A(H5N1) is an infectious disease caused by an influenza A virus.
- From January 1, 2003, to September 29, 2025, a total of 991 human cases of avian influenza A(H5N1) and 476 deaths (a case fatality rate of 48%) have been reported to WHO from 24 countries.
- The 11 recent deaths that occurred in Cambodia (8), India (2), and Mexico (1) were associated with direct contact with poultry and/or wild birds.
- No person-to-person transmission has been identified in any of these cases.
The route by which the avian influenza virus is introduced into cattle remains uncertain, potentially linked to the consumption by dairy cows of bedding soiled by infected bird droppings.
These sporadic human infections are accompanied by infections in new species of wild and domestic mammals that were previously spared. This follows a continuous circulation of the virus in wild bird colonies, leading to an unprecedented increase in the number of outbreaks in poultry farms in many countries in Africa, Asia, Europe and North America.
Learn more about EmergenceFollow the latest scientific news on the subject
As part of the ANRS MIE Emergence program, the agency publishes a monthly scientific review on avian influenza A (H5N1), providing updates on the most recent research findings.
Find out more
Avian influenza A (H5N1)
Avian influenza, also known as bird flu or formerly fowl plague, caused by A strains of the influenza virus, is an infectious disease affecting wild and domestic birds.
29 July 2024
Viral haemorrhagic fevers
Viral haemorrhagic fevers (VHFs) include various diseases (Ebola, Lassa fever, Marburg fever, Crimean-Congo fever, etc)
12 March 2024
Viral hepatitis
Viral hepatitis is inflammation of the liver caused by any of the viruses A, B, C, D and E
12 March 2024