Experts confirm the first case: ScienceAlert

It’s now official: the highly pathogenic avian influenza A(H5N1) that has been spreading around the world since 2020 is now transmitted from a cow to a dairy farmer in the United States, the first confirmed transmission of this cow virus to man never recorded. .

The good news is that the case was detected quickly and the virus manifested itself as inflammation of the eye, rather than any type of upper respiratory infection. So the chances of it being passed on to someone else, if human-to-human transmission is still possible, are lower.

Additionally, after nervously watching its spread among poultry and wildlife, we now have solid data on how the bird flu occurs in humans, which should help experts assess the threat to public health – and identify more cases if and when they appear.

“It’s a huge thing that the virus jumped from birds to mammals, in this case to dairy cows, and then to humans,” says environmental toxicologist Steve Presley, director of the Biological Threat Research Laboratory at Texas Tech University .

Presley and his colleagues are behind the recently published paper on this unique case of bird-to-cow-to-human transmission. flu transmission, confirmed by testing conducted under highly biosafe laboratory conditions and shared with the U.S. Centers for Disease Control and Prevention (CDC).

The farm worker reported redness and discomfort in his right eye near the end of March 2024. Although he did not have contact with birds or poultry, he worked with cows, including some showed signs of illness.

It is only recently that this bird flu transmitted from poultry to livestock in the United States, which came as a surprise to experts because it was the first time highly pathogenic avian influenza (HPAI) had been detected in dairy cattle. Closer monitoring of dairy cows and those who come into contact with them will now be necessary.

This is only the second human case of this bird flu in the United States, and human-to-human transmission has not yet been observed anywhere. But each time the pathogen finds a human host, it is more likely to adapt and mutate to become more infectious to our species – which appears to have happened in this case.

“The virus identified in the worker sample exhibited a change (PB2 E627K) that has been associated with viral adaptation to mammalian hosts and previously detected in humans and other mammals infected with HPAI A(H5N1) and other subtypes of avian influenza A viruses,” Presley and colleagues from the CDC and Texas state health officials write in their paper.

The current bird flu The outbreak began in 2020, and although human infection is rare, the mortality rate is high. This means it is essential that we understand how diseases are transmitted between animals and where this happens.

We know that it now exists in a multitude of mammals, including foxes, seals, sea lions, bears and domestic cats. With the stakes so high and the pandemic still fresh in people’s minds, scientists are working tirelessly to try to minimize the current spread of the flu.

“(This study) is going to lay the foundation, I believe, for a lot of future research into the evolution of the virus,” Presley says.

The research was published in The New England Journal of Medicine.