Avian influenza, or bird flu, is not a new disease, despite recently occupying the spotlight after an outbreak among dairy cattle in the United States of America. In fact, the virus causing the current outbreaks – H5N1 – first emerged in 1996/1997 in Hong Kong and later re-emerged in 2003/2004.
Avian influenza has continuously evolved since then, and is commonly found in farmed poultry and wild birds around the world. It can also spill over into mammal populations; in the WHO European Region, it has been detected in farmed mink and foxes.
The Region experienced one of its worst spates of avian influenza infections between October 2021 and September 2023, resulting in the deaths of millions of wild birds and causing 2500 outbreaks on farms in 37 countries.
Globally, while the H5N1 virus continues to spill over to more mammals, infections in humans happen only very occasionally. As of July 2024, around 10 human cases have been reported from the outbreak among cattle in the United States, although it continues to affect over 100 cattle herds.
Recent global reports also detected different subtypes of the virus in the human population, with one fatality from H5N2 in Mexico and a recovered case of less pathogenic H5N1 in Australia – the first ever in the country.
Within the Region, Finland just announced that it will start vaccinating its at-risk populations, mainly farm workers and veterinarians, against the disease. WHO/Europe also has a quadripartite agreement with the United Nations Food and Agriculture Organization, the United Nations Environment Programme, and the World Organisation for Animal Health to strengthen and optimize the health of humans, animals, plants and the environment in the face of future threats.
So, is avian influenza cause for concern? Aisling Vaughan, an epidemiologist at WHO/Europe working specifically on zoonotic influenza, explains what avian influenza means for the Region now and whether it may pose a risk in the future.
This article was amended on 24 July 2024, as the previous version incorrectly mentioned that fewer than 10 human cases of H5N1 have been reported from the USA, when it should have been approximately 10, since 4 were reported following exposure to dairy cows and 7 were reported following exposure to poultry.