The World Health Organization warned Wednesday that the recent surge in bird flu outbreaks among mammals could help the virus spread more easily among humans.

Since late 2021, Europe has been gripped by its worst-ever outbreak of bird flu, while North and South America have also experienced severe outbreaks.

This has led to the culling of tens of millions of poultry worldwide, many with the H5N1 strain of the virus, which first emerged in 1996.

But there has recently been a worrying spike in infections in mammals.

“Avian influenza viruses normally spread among birds, but the increasing number of H5N1 avian influenza detections among mammals—which are biologically closer to humans than birds are—raises concern that the virus might adapt to infect humans more easily,” the WHO said in a statement.

“In addition, some mammals may act as mixing vessels for influenza viruses, leading to the emergence of new viruses that could be more harmful to animals and humans.”

Outbreaks have been reported in 26 species, including farmed mink in Spain and sealions in Chile. H5N1 was recently detected in cats in Poland.

‘Paradigm change’

The WHO, along with the UN’s Food and Agriculture Organization (FAO) and the World Organisation for Animal Health (WOAH), urged countries to work together to save animals and protect people.

“There is a recent paradigm change in the ecology and epidemiology of avian influenza which has heightened global concern as the disease spread to new geographical regions and caused unusual wild bird die-offs, and alarming rise in mammalian cases,” said WOAH science chief Gregorio Torres.

Infections in humans can cause severe disease with a high mortality rate.

Human bird flu cases are usually the result of direct or indirect exposure to infected live or dead poultry or contaminated environments.

“The virus does not appear to be able to transmit from one person to another easily, but vigilance is needed to identify any evolution in the virus that can change that,” said the WHO’s pandemic preparedness chief Sylvie Briand.

Experts were looking for changes that could be more dangerous to humans, and urged countries to boost their monitoring capabilities, she added.