Doctors are alarmed by a mutated form of bird flu that infected a farm worker in Texas.
The patient contracted the virus, his eyes became red and itchy, from contact with an infected dairy cow or chicken in Texas.
Government-backed researchers sampled the virus, infected mice and ferrets, and found that it had evolved to become much more lethal than the wild strain currently spreading on American farms.
It also spread among animals through the air, a key milestone that would theoretically allow it to be more contagious in humans.
But most importantly, tests showed that some antiviral drugs could work against this strain of the virus if this were the case.
Experts are now warning health officials to more closely monitor the movement of the virus to contain the outbreak before it can evolve further and infect more humans.
Discussing the research, government officials said: “These mutations underscore the need for continued monitoring and evaluation of viruses from the current H5N1 outbreak.”
So far, 34 humans in the US have been infected with bird flu in 2023, 33 of which have been linked to contact with infected cows or poultry.
The image above of the symptoms suffered by the Texas dairy farmer who contracted bird flu was published in the New England Journal of Medicine.
The virus is not known to be transmissible between humans. Still, an unidentified Missouri man contracted the disease without ever coming into contact with an infected animal.
Researchers have suggested that drinking unpasteurized milk from an infected cow or raw egg from an infected hen could also spread the virus.
Bird flu has been ravaging the United States for the past few months, affecting Texas, New Mexico and Missouri.
It causes redness, itchy eyes, and mild respiratory symptoms.
Last week, the bodies of dairy cows piled up in California as farm workers tried to contain the spread of the disease, which affected 124 dairy cow herds.
In the new paper, researchers funded by the National Institute of Allergy and Infectious Diseases (NIAID) took a sample of the H5N1 virus from the eye of a Texas dairy worker who had been infected with the disease to see how it would affect animals in the laboratory. .
They tested it in both mice and ferrets, and observed that ferrets tend to have a similar response to the flu virus as humans.
They published their findings as a preprint, meaning they have not yet been reviewed by other scientists, in the nature magazine.
They found that the virus had mutated and could pass through the air, affecting between 17 and 33 percent of ferrets placed in neighboring cages.
Dead cows are piling up in California as dairy farmers battle H5N1 bird flu, which made landfall in the state in August.
The study also compared the amount of the huTX37-H5N1 strain needed to kill a mouse and compared it to a non-mutated H5N1 strain from a study published in Nature in July.
It found that it took less than one unit of the huTX37-H5N1 virus to kill a mouse, compared to 31.6 units of the H5N1 virus in July.
This suggests that the mutated virus could be 30 times more potent than older strains.
One week after being directly infected with the virus, all of the ferrets that were directly infected with the virus by the researchers died from the disease. It is unclear whether the animals that contracted the virus in the air died.
At this point, researchers say that humans can only contract the virus when they come into direct contact with bodily fluids from an infected animal.
But if the virus can spread through the air, it has the potential to infect many more people.
The NIAID study found that some antiviral drugs were able to stop the symptoms of the virus, including some, like Xofluza, that are already on the market.
The study authors said: “Based on these observations, every effort should be made to contain outbreaks of HPAI H5N1 in dairy cattle to limit the possibility of further human infections.”