The strain of bird flu that infected one person in Texas has mutated to spread more easily, officials say, amid growing alarm that the disease could spread to more people.
The CDC said tests on the H5N1 sample showed it had a mutation that was “known to be associated with viral adaptation to mammalian hosts,” but insisted the mutations were minor and the overall risk to the public was low. .
This mutation was not detected in cattle or wild birds, and officials said it “may have been acquired in the patient during the development of the (eye infection).”
Meanwhile, three pet cats have reportedly died from bird flu after contracting the disease on Texas dairy farms, as fears grow that infected animals living near humans could spread the disease to people.
And the largest US egg producer has revealed that bird flu has been detected in its flock, and almost 2 million chickens will now be culled. There is growing concern that the outbreak on farms could cause supply chain problems or drive up the price of eggs and dairy products.
It comes amid concerns that H5N1, which has already triggered a pandemic in the animal world, could soon do the same in humans.
A cat photographed in close contact with dairy cows. Three domestic cats on an infected dairy farm in Texas died after contracting H5N1 (file image)
Infectious disease experts warn that each infection in mammals or humans increases the risk of the virus acquiring new mutations that allow it to infect people.
Dr. Francois Balloux, a UK epidemiologist, warned in X that the situation “could worsen over time.”
But he added: “People who are not professionally involved in pandemic prevention/mitigation and who are worried or miserable now won’t make any material difference to what it might affect us, except that their life would be shit, a lot more than what should”.
Dr Peter Hotez, a virologist at Baylor College of Medicine in Texas, told DailyMail.com that the cases were “a reminder that avian flu is continually circulating and jumping to new mammalian hosts”.
“So far, post-human jumps remain rare and do not cause serious illness,” he added, “but I think this could change over time.”
The mutation detected in the virus that infected a dairy farm worker in Texas was recorded previously, the CDC said, and did not cause a major outbreak at the time.
The change, in the PB2 gene related to the way the virus copies itself, has not been recorded in wild poultry or infections in cows.
The graph above shows human cases of avian influenza reported globally by year. The colors represent different countries, with light blue being Egypt and orange being Cambodia.
The CDC said: ‘It is important to note that this substitution has not been observed in the available PB2 genes of viruses circulating in wild birds or in the recently described bovine viruses detected in Texas.
“(This suggests that) the mutation may have been acquired in the patient during the development of conjunctivitis.”
Bird flu makes millions of copies of itself in infected cells before infecting other cells.
Several of these copies contain mutations that could be dangerous and improve the virus’s ability to infect or spread among mammals.
The Texas patient had only one symptom, an eye infection, although experts warn that the mutations could cause more serious cases.
All infections in the three cats were reportedly confirmed on dairy farms that experienced outbreaks of the virus.
So far, seven dairy farms in Texas have reported outbreaks, two in Kansas, one in New Mexico and one in Michigan. There are also suspicions about another outbreak at a farm in Ames, Iowa.
Infected cows are reported to be “lethargic,” eating less feed and producing less milk than before, although they do not die from the disease.
Bird flu began to take off in 2020 after a wild bird flu swapped genes with a version of the virus from domestic poultry.
It spread rapidly through migratory birds and in May 2021 it was confirmed to have crossed the barrier between birds and mammals for the first time. – after two fox cubs in the Netherlands tested positive for the disease.
One died from the infection, while the other was euthanized due to his symptoms. The route of infection was not confirmed, but scientists said it was probably by eating the carcass of an infected bird.
In January 2022, the first case in a human being was diagnosed: Alan Gosling, 79, from the United Kingdom.
The former engineer had contracted the virus from one of the 20 Muscovy ducks he shared his home with and only had mild symptoms.
Just three months later A second human case was reported in an inmate working on a poultry farm in Colorado.
The patient also suffered only mild symptoms (“fatigue for a few days”) and then recovered after taking the antiviral drug oseltamivir.
In November 2022, China recorded the first death from the virus: a poultry farm worker who was infected with H5N1.
Sporadic cases have been detected since then, but experts say the numbers are still much lower than the outbreak in Egypt around 2015, when more than a hundred cases were detected.
Bird flu began spreading to domestic birds in February 2022, when the United States revealed that it had detected H5N1 in a flock of turkeys.
That year alone, an estimated 52 million birds had to be slaughtered to stop the spread of the virus, driving up the price of eggs and chicken meat.
More cullings were carried out in 2023 and again this year, and the total number of birds culled is now estimated to exceed 82 million.
There are also concerns that the virus could spread to other animals that come into closer contact with humans after a dog in Ottawa, Canada, tested positive in April 2023.
And there are signs that it is gaining the ability to spread among mammals, including seals, after 17,000 pups died in a colony in Patagonia.
Experts said at the time that the animals had been infected with bird flu and warned that it was likely spreading among local animals.