United States: A type of bird flu called H5N1 was found in a dairy worker in Texas this spring. Scientists at the University of Wisconsin–Madison studied this virus and found that it can spread through the air between ferrets, even though it doesn’t spread very well. Sadly, all the ferrets that got infected with this virus in the study died.
The good news: The dairy worker had mild symptoms and recovered completely while neither has the H5N1 strain that infected the worker continued circulating in the wild.
Nevertheless, these revelations raise potential danger from a virus which persists in circulating through the dairy herd and occasionally jumping to farm personnel, and the study ‘s principal investigator said he was taken aback by just how effectively this particular strain of virus was able to kill ferrets.
As reported by the Medicalxpress, “This is one of the most pathogenic viruses I’ve ever seen in ferrets,” says Yoshihiro Kawaoka, a UW–Madison professor of pathobiological sciences who led the work, detailed in a Nature article published October 28.
Ferrets are used commonly as a model to understand how avian influenza viruses capable of infecting mammals are transmitted, a subject of interest of Kawaoka and his team at Influenza Research Institute at UW–Madison.
As with other influenza viruses, H5N1 viruses, in their interactions with new hosts, evolve relatively quickly. At other times the viruses are able to increase their infection rates by transitioning to new host organisms at increased rates. This is how the current viruses, which have been flowing throughout the avian populations of the world in the recent years, started spreading among the mammals, with the instance of some North American dairy cattle in 2024.
Kawaoka and his collaborators confirmed that the H5N1 virus that infected the Texas dairy worker carried a mutation that the team identified in 2001 as being relevant to severe disease. Thankfully, though, the strain with that mutation appears to have gone away, according to Kawaoka.
“This isolate is rather different from other circulating H5N1 viruses in cows,” he says.
Kawaoka estimates that H5N1 viruses followed two directions the moment they quarantined from bird and infected the mammals, thanks to mutation that compiled the virus to end host cows.
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