- In rare cases, humans have contracted the virus, sometimes fatally, usually after coming into close contact with infected birds.
- „Something happened’ in mid-2021 that made this group of viruses much more infectious.
- The study showed that the virus has increased in virulence, meaning it causes more dangerous diseases.
While stressing that the risk to humans remains low, experts who spoke to AFP said the increasing number of cases of bird flu in mammals was a cause for concern. Since its emergence in 1996, the H5N1 avian influenza virus has previously been confined to outbreaks of avian influenza, mostly seasonal. „Something happened” in mid-2021 that made this group of viruses much more infectious, according to Richard Webby, head of a World Health Organization collaborating center that studies influenza in animals.
Since then, outbreaks have lasted throughout the year, spreading to new areas and leading to mass deaths among wild birds and the culling of tens of millions of poultry. Webby, who is a researcher at St Jude Children’s Research Hospital in the US city of Memphis, told AFP that he is „absolutely” the biggest bird flu outbreak the world has seen.
He led research, published this week in the journal Nature Communications, that shows how the virus evolved rapidly as it spread from Europe to North America. The study showed that the virus increased in virulence, meaning it causes more dangerous disease, when it reached North America.
The virus causes more serious illness than previous strains
The researchers also infected a ferret with one of the new strains of bird flu. They found an unexpected amount of „huge” amount of virus in his brain, Webby said, indicating that it caused more severe disease than previous strains.
Stressing that the risk in humans is still low, he said that „this virus is not static, it changes.” „This raises the potential that, even just by chance,” the virus could “pick up genetic traits that allow it to be more of a human virus,” he said.
In rare cases, humans have contracted the virus, sometimes fatally, usually after coming into close contact with infected birds.
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