Experts warn of rapidly evolving avian flu virus

A worker stands in front of a seabird suspected to have died from H5N1 avian influenza on a beach in Lima, on December 1, 2022. The highly contagious H5N1 avian flu virus has killed thousands of pelicans, blue-footed boobies and other seabirds in Peru, according to the National Forestry and Wildlife Service (SERFOR). (Photo by Ernesto BENAVIDES / AFP)

The H5N1 virus, which led to a record wave of avian flu in the world, is evolving rapidly, warn experts, while increasing requests for countries to vaccinate their birds.

If the risk for humans remains small, the growing number of cases among mammals is considered worrying, according to experts interviewed by AFP.

Since its appearance in 1996, the H5N1 avian flu virus has caused seasonal infections.

But “something happened” in mid-2021, as the virus became more infectious, according to Richard Webby, a virologist and director of the World Health Organization’s Center for Research on Avian Pathologies.

Since then, epizootics have become annual and have spread to new regions, causing large-scale deaths of wild birds and the elimination of tens of millions of birds.

For Webby, this is the biggest bird flu epizootic ever known.

Richard Webby coordinated the research, published this week in the journal Nature Communications, which shows that the virus evolved rapidly, spreading from Europe to North America.

Scientists also infected a ferret with one of nine strains of avian flu. They found a “huge” and unexpected amount of virus in his brain, which shows a more severe disease than with previous strains, he told AFP.

Although noting a still small risk for humans, Webby highlighted that “this virus is not static, it evolves, which increases the risk that, even by chance, the virus may acquire genetic traits that allow it to become a human virus” .

There are few cases of humans who have contracted the sometimes deadly virus, usually after close contact with infected birds.

But detection of the disease in a growing number of mammals, including new species, is “a truly worrying sign,” Webby said.

Last week, Chile announced that nearly 9,000 seabirds had died of bird flu off the country’s northern coast since early 2023. Most reportedly contracted the virus after eating infected birds.

“Recent transmissions to mammals must be closely monitored,” warned World Health Organization Director General Tedros Adhanom in February.

However, there is “no clear evidence that this virus remains readily in mammals”, according to Ian Brown, director of virology at the UK Plant and Animal Health Agency.

And even if the virus continues to evolve to be “more effective in birds”, it remains “inappropriate for humans”, he told AFP.

One of the biggest ways to decrease the number of avian flu cases and reduce the risk to humans would be to vaccinate birds, said Richard Webby.

Some countries, including China, Egypt and Vietnam, have already organized vaccination campaigns. But others balk at possible restrictions on imports and fears that infected birds will slip through controls.

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2023-06-05 02:02:48