The recent surge in bird flu outbreaks among mammals could help the virus spread more easily among humans, United Nations agencies Food and Agriculture Organization (FAO), the World Health Organization (WHO) and World Organisation for Animal Health (WOAH) warned July 12, 2023.
The agencies urged countries to strengthen disease surveillance and improve hygiene at poultry farms.
A new H5N1 strain of bird flu explosively spread to new geographical regions earlier this year, the agencies said. The strain, which was highly contagious to wild birds, infected and killed a variety of mammal species and raised fears of a pandemic among humans.
“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 agencies said.
Human bird flu cases are usually the result of direct or indirect exposure to infected live or dead poultry or contaminated environments.
About 10 countries have reported cases of avian flu outbreaks in both land and sea mammals since 2022, including in farmed mink in Spain, seals in the United States, and sea lions in Peru and Chile. Outbreaks have been reported in 26 species and H5N1 was recently detected in cats in Poland.
Some of these infected 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, the agencies feared.
However, only about half a dozen cases in people who had close contact with infected birds have been reported to the WHO and most of those have been mild.
“We encourage all countries to increase their ability to monitor these viruses and to detect any human cases,” said Sylvie Briand, the director of epidemic and pandemic preparedness and prevention at the WHO.
The agencies urged countries to share genetic data of viruses from humans and animals in publicly accessible databases. They also suggested several measures to curb the spread of the virus:
A host of mammal species are known to be infected to date, like ferret, mink, several otter species, European badger, skunk and Virginia opossum.
Felines like Amur leopard, Amur tiger, mountain lion, European polecat, lynx, bobcat, and domestic cats have been reportedly infected as well, along with red fox, coyote, racoon, racoon dog, South American bush dog, American black bear, brown Bear and grizzly bear.
The goose / Guangdong-lineage of H5N1 avian influenza viruses first emerged in 1996 and has been causing outbreaks in birds since then. Since 2020, a variant of these viruses has led to an unprecedented number of deaths in wild birds and poultry in many countries in Africa, Asia and Europe.
In 2021, the virus spread to North America, and in 2022, to Central and South America.
In 2022, 67 countries in five continents reported H5N1 high pathogenicity avian influenza outbreaks in poultry and wild birds to WOAH, with more than 131 million domestic poultry lost due to death or culling in affected farms and villages. In 2023, another 14 countries reported outbreaks.