If for the time being the H5N1 virus is not very dangerous for humans, a few changes to the virus would be enough to change the situation.
By Le Figaro with AFP
Published
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The H5N1 virus, responsible for a record outbreak of bird flu across the world, is changing rapidly, experts warn as calls grow for countries to vaccinate their poultry. While the risk to humans remains low, the increasing number of mammalian cases is considered cause for concern.
Since its appearance in 1996, the H5N1 avian influenza virus has caused essentially seasonal epizootics. But “Something happenedin mid-2021 which made it much more infectious, according to Richard Webby, virologist and director of the World Health Organization’s (WHO) Avian Pathology Research Center. Since then, epizootics have become annual, extended to new areas and synonymous with massive deaths of wild birds and the slaughter of tens of millions of poultry.
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“The virus is not static, it evolves”
For Richard Webby, it is the most important epizootic of bird flu ever known. He conducted research, published this week in the journal NatureCommunications showing that the virus rapidly evolved as it spread from Europe to North America.
The researchers also infected a ferret with one of the new strains of bird flu. They found a quantityenormous” and unexpected virus in his brain, translation of a disease more serious than with the previous strains. While pointing to a still low risk in humans, Richard Webby observed that “this virus is not static, it evolves“, what “increases the risk that, even by chance“, the virus can”acquire genetic traits allowing it to be more of a human virus“.
For now, cases of humans contracting the sometimes fatal virus, usually after close contact with infected birds, are rare. But the detection of the disease in a growing number of mammals, including new species, is “a really worrying sign“, according to Richard Webby.
Last week, Chile announced that nearly 9,000 sea lions, penguins, otters, porpoises and dolphins have died of bird flu on its northern coast since early 2023. Most are believed to have contracted the virus from eating infected birds.
“Recent transmissions to mammals should be closely monitored“Warned WHO boss Tedros Adhanom Ghebreyesus in February.
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Of course, there is noclear evidence that this virus is easily maintained in mammals“, according to Ian Brown, head of virology at the UK Animal and Plant Health Agency. And, if the virus evolves to become “more efficient in birds“, he’s staying “unsuitable for man“.
Avian viruses indeed bind to different receptors on the host cell compared to human viruses, specified Richard Webby, explaining that it would be necessary “two or three minor mutations in a virus proteinto make them more human-friendly.
Vaccinate animals?
One of the ways to decrease the number of bird flu cases and reduce the risk to humans would be to vaccinate poultry, said Richard Webby.
Some countries, including China, Egypt or Vietnam, have already organized such vaccination campaigns. But many others are reluctant due to possible import restrictions and fears that infected birds will fall through the cracks.
In April, the United States began testing several vaccine candidates for potential use in birds. France recently indicated that it hopes to start vaccinating poultry this fall.
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Vaccination of poultry is nota miracle solution because the virus is constantly changing“, according to Christine Middlemiss, chief veterinarian of the United Kingdom. But traditionally reluctant countries should consider using it more often, she told an event at the UK Embassy in Paris last week.
For the Director General of the World Organization for Animal Health, Monique Eloit, the issue of vaccination of poultry should be “on the table“. After all, she recalls,everyone now knows that a pandemic isn’t just a fantasy, it could be a reality“.