The World Health Organization expressed concern Thursday about the transmission of H5N1 avian flu to new species, including humans, who have a “extraordinarily high” fatality rate.
“This remains, I believe, an enormous concern,” the UN health agency’s top scientist, Jeremy Farrar, told reporters in Geneva.
The current bird flu outbreak began in 2020 and has killed tens of millions of chickens, as well as wild birds, terrestrial animals, and seabirds.
Cows and goats were added to the list last month, which surprised researchers because they were not previously thought to be susceptible to this kind of influenza.
According to Farrar, the A (H5N1) strain has become “a global zoonotic animal pandemic”.
“The great concern of course is that in… infecting ducks and chickens and then increasingly mammals, that virus now evolves and develops the ability to infect humans and then critically the ability to go from human to human.”
So far, there is no proof that the influenza A(H5N1) virus is circulating among humans.
However, “the mortality rate is extraordinarily high” in the hundreds of cases when humans have been infected through contact with animals, according to Farrar.
From the beginning of 2023 to April 1 this year, the WHO reported 463 deaths from 889 human cases in 23 countries, resulting in a case fatality rate of 52 percent.
In a disturbing development, US authorities reported earlier this month that a person in Texas was recovering from bird flu after being exposed to dairy cattle.
It was only the second incidence of a human testing positive for bird flu in the country, and it came after the virus infected cattle that had evidently been exposed to wild birds in Texas, Kansas, and elsewhere.
It also appears to be the first human infection with the influenza A(H5N1) virus subtype caused by contact with an infected mammal, according to WHO.
Whenever “you come into the mammalian population, then you’re getting closer to humans,” Farrar said. He added that “this virus is just looking for new, novel hosts” .
“It’s a real concern.”
Farrar emphasized the need for more surveillance, stating that understanding the number of human infections is crucial for virus adaptability.
“It is a horrible thing to say, but if I become infected with H5N1 and die, that will be the end of it. If I go around the neighborhood and spread it to someone else, you will start the cycle.”
He stated that work were underway to develop vaccines and therapies for H5N1, and emphasized the importance of ensuring that regional and national health authorities around the world are capable of diagnosing the virus.
This was done so that “if H5N1 did come across to humans, with human-to-human transmission,” the world would be “in a position to immediately respond,” Farrar said, advocating for fair access to vaccines, treatments, and diagnostics.