The bovine flu virus that has spread through US dairy herds may have taken a “dangerous” step towards infecting humans through respiratory infections, scientists have warned.
He H5N1 viruswhich is most commonly found in birds, has until now been confirmed in cattle on more than 100 farms in 12 states, and inactivated fragments of the strain were found in pasteurized milk on supermarket shelves.
So far, four people who work with animals have been infected, although the symptoms were mild and they did not transmit the virus to anyone else.
Now, a detailed analysis by scientists at the University of Wisconsin-Madison in the US shows that viral samples taken from cows were able to bind to receptors found on cells in the human respiratory tract.
The version of H5N1 found in birds cannot do that, suggesting that the bovine virus has mutated.
Additional testing on ferrets, which are commonly used in flu research, found that the cow virus did not spread easily through respiration.
However, Dr Ed Hutchinson, of the Medical Research Council and Virus Research Center at the University of Glasgow, said there was still “reason for concern”.
“Urgent” action needed
“When they compared their bovine flu isolate to bird flu, they found that it had already begun to acquire some of the properties that would be associated with the ability to spread effectively through respiratory infections in humans,” said Dr. Hutchinson, who did not participated in the study. study, he said he.
“To be clear, it does not appear to be doing this yet, and none of the four human cases reported so far have shown signs of further transmission.
“However, this new H5N1 influenza virus would be even more difficult to control, and even more dangerous to humans, if it gained the ability to spread effectively via the respiratory route.
“While it is good news that bovine flu cannot yet do this, these findings reinforce the need to take urgent and decisive action to closely monitor this outbreak and try to control it as soon as possible.”
Unlike normal human flu, which is contained in the respiratory tract, H5N1 can spread to other organs in the body, with as yet unknown effects.
The US government recently gave COVID vaccine maker Moderna £139 million to develop a vaccine against H5N1.
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The company’s mRNA technology can be easily modified to match evolving viruses and then quickly deployed if there is an outbreak in humans.
The World Health Organization says the current risk to people is low.
But scientists were stunned by the sudden appearance of the virus in cattle, a species not previously recognized as at risk, raising fears that it could cause a human pandemic in the future.
The research is published in the scientific journal Nature.
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