Experts warn of the pandemic threat of bird flu

Health experts have sounded the alarm about the potential pandemic threat posed by bird flu, which is showing signs of mutating as the disease spreads among cows and infects people in the United States.

There is no guarantee that bird flu will ever be transmitted between humans, and US health authorities have stressed that the risk to the general public remains low.

The deadly H5N1 bird flu strain first emerged in China in 1996, but over the past four years has spread more widely than ever before, reaching previously pristine areas such as the penguin paradise of Antarctica.

More than 300 million poultry birds have been killed or culled since October 2021, while 315 different species of wild birds have died in 79 countries, the World Organization for Animal Health told AFP.

Mammals that ate the infected birds, such as seals, have also suffered mass deaths.

The situation changed again in March, when the virus again began spreading among dairy cows in the United States for the first time.

Fifty-eight people have tested positive for bird flu in the U.S. this year, including two who are not known to have been exposed to infected animals, according to the Centers for Disease Control and Prevention.

There are also fears that some human cases may go undetected. Researchers said last month that eight of 115 dairy workers tested in Michigan and Colorado had antibodies against bird flu, indicating an infection rate of seven percent.

Meg Schaeffer, an epidemiologist at the US-based SAS Institute, told AFP that there are now several factors indicating that “bird flu is knocking on our door and could cause a new pandemic any day”.

“A bird flu pandemic would be one of the most predictable catastrophes in history,” was the headline in an opinion article in the New York Times late last month.

‘Simple step’ away

There are still several barriers that prevent H5N1 from spreading easily between people, including that the virus would have to mutate to become better at infecting human lungs.

But research published in the journal Science showed Thursday that the version of bird flu infecting American cows is now just a single mutation away from spreading more effectively among humans.

Virologist Ed Hutchinson from the University of Glasgow said this suggests H5N1 is just “one simple step” away from becoming “more dangerous to us”.

And last month, genetic sequencing of a Canadian teenager who was very ill with bird flu “implied that the virus was beginning to evolve to explore ways to bind more effectively to the cells in their body,” Hutchinson said.

“We don’t yet know whether the H5N1 flu viruses will evolve into a human disease,” and other barriers remain, Hutchinson points out.

But the more animals and different species the virus is allowed to infect, the “greater chance it has of adapting to better infect humans,” Schaeffer said.

And if a bird flu pandemic were to occur, it would be “remarkably severe” in humans because we have no built-up immunity, she added.

The cases of U.S. farmworkers have been relatively mild so far. But according to the World Health Organization, nearly half of the 904 human cases of H5N1 recorded since 2003 have been fatal.

Raw milk: ‘terrible idea’

Tom Peacock, a virologist at Imperial College London, told AFP there are several reasons to be “less pessimistic about the possibility of a pandemic”.

Antiviral treatments and vaccines are already available for bird flu, which is a big difference from Covid-19 in 2020, he pointed out.

To avoid the worst-case scenario, many health researchers have called on the U.S. government to increase testing and ensure information is shared between agencies and countries.

On Friday, the U.S. Department of Agriculture announced plans to test the country’s milk supply for bird flu.

Of particular concern is raw or unpasteurized milk, which has been repeatedly found to be contaminated with bird flu.

Vaccine skeptic and conspiracy theorist Robert F. Kennedy Jr., who was picked by US President-elect Donald Trump as health secretary, is known to be a fan of raw milk.

California raw milk producer Mark McAfee, whose products have been repeatedly recalled due to bird flu, told The Guardian last week that Kennedy’s team had approached him to lead the incoming administration’s raw milk policy.

Schaeffer said any suggestion to lift restrictions on raw milk “is unequivocally a terrible idea and absolutely endangers human health.”

© 2024 AFP