Bird Flu Virus Changing Rapidly In Largest-Ever Outbreak, Warn Experts

But "something happened" in mid-2021 that made the group of viruses much more infectious, according to Richard Webby, the head of a World Health Organization collaborating centre studying influenza in animals.

The virus causing record cases of avian influenza in birds across the world is changing rapidly, experts have warned, as calls increase for countries to vaccinate their poultry.

While emphasising that the risk to humans remains low, the experts who spoke to AFP said that the surging number of bird flu cases in mammals was a cause for concern.

Since first emerging in 1996, the H5N1 avian influenza virus had previously been confined to mostly seasonal outbreaks.

But "something happened" in mid-2021 that made the group of viruses much more infectious, according to Richard Webby, the head of a World Health Organization collaborating centre studying influenza in animals.