Rapidly mutating ‘bovine flu’ takes ‘dangerous step towards infecting humans’, scientists warn

The bird flu virus spreading in US dairy cows may be better at infecting humans than other circulating strains of the virus, scientists have warned.

The H5N1 virus, normally found in poultry, has been confirmed in cows from 140 farms in 12 states, with traces also found in pasteurized milk sold on supermarket shelves.

4

The outbreak is believed to have started when cows on a Texas farm contracted the virus from wild birds.

At least four people who work closely with the animals contracted the virus, although their symptoms were mild and they did not transmit the virus to others.

New research carried out by scientists at the University of Wisconsin-Madison, in the USA, shows that the new bovine virus can bind to receptors on cells in the human respiratory tract.

These receptors are how flu viruses normally enter and infect human cells.

The version of H5N1 found in birds cannot do this, suggesting that the bovine virus has mutated.

This new H5N1 flu virus would be even more difficult to control, and even more dangerous to humans, if it gained the ability to effectively spread respiratory infections.

Dr. Ed Hutchinson

The study also confirmed that the virus can be transmitted efficiently through contaminated milk.

Milk from an infected cow in New Mexico sickened rats and ferrets after consuming just a drop.

Additional testing on ferrets, however, revealed that the virus could not spread as effectively by simply breathing.

4

In the experiment, a sample of the H5N1 strain of bird flu was placed close to healthy animals, but not close enough for physical contact.

None of the four healthy ferrets on display became sick or showed symptoms.

Only one ferret produced antibodies against the virus, experts later discovered, suggesting it had been infected.

A virus that can easily spread through the air between humans would pose a greater pandemic threat than H5N1 currently poses.

‘HARDEST TO CONTROL’

Despite this good news, Dr Ed Hutchinson, from the Medical Research Council and Virus Research Center at the University of Glasgow, said there is still “cause for concern”.

“When they compared their bovine flu isolate to bird flu, they found that it had already begun to gain some of the properties that would be associated with the ability to spread effectively through respiratory infections in humans,” said Dr. Hutchinson, who was not involved in the study. study, he said.

“To be clear, this does not appear to be happening yet, and none of the four human cases reported so far have shown signs of onward transmission.

“However, this new H5N1 flu virus would be even more difficult to control, and even more dangerous to humans, if it gained the ability to spread effectively respiratoryly.

“While it is good news that cow flu cannot yet do this, these findings reinforce the need for urgent and determined action to closely monitor this outbreak and try to control it as quickly as possible.”

4

WHAT IS BIRD FLU?

H5N1 first emerged in 1996, but since 2020 the number of outbreaks in birds has grown exponentially.

Since then, the virus has killed millions of birds and thousands of mammals around the world.

The World Health Organization (WHO) states that the current risk to people is low, as there is still no evidence of any transmission between humans.

Experts fear that the scale of the current outbreak could give the virus more opportunities to mutate, allowing H5N1 to spread better in humans.

Existing evidence shows that the mortality rate in humans can reach 60%.

At least 882 people have been infected with bird flu in the last 20 years – and 461 of them have died.

There is no human bird flu vaccine on the market, but the UK government is said to be drawing up plans to stockpile regular flu vaccines in case of a pandemic.

The research is published in the scientific journal Nature.