Bird flu could cause the next pandemic in humans, the CDC warned, as the H5N1 strain spreading on farms continued to mutate.
In a report quietly released late last week, the agency said bird flu viruses “have pandemic potential” in a section on vaccine rollout if there is human contagion.
Also last week, a separate U.S. Department of Agriculture study released genetic data showing that the H5N1 strain sweeping dairy farms had acquired dozens of new mutations.
These changes could make the strain more likely to spread from cows to other animals, including people, and make the virus resistant to antivirals.
Despite this, the CDC and the World Health Organization (WHO) insist that the risk to the American public is low.
The map above shows states where avian flu infections have been detected in dairy herds.
This is the first photograph of the Texas farm worker infected with bird flu. The infection started in the right eye, before spreading to the left.
The WHO said today: ‘At present, based on available information, WHO considers the overall public health risk posed by H5N1 to be low.
‘(But) for those with exposure to infected birds or animals or contaminated environments, the risk of infection is considered low to moderate.
“This risk requires close monitoring and WHO and its partners will continue to regularly assess and publish public health risk assessments of avian influenza.”
The agency held a webinar today, attended by its own infectious disease experts as well as CDC officials.
The meeting came after USDA researchers warned about new H5N1 mutations.
They wrote: ‘Some (mutations) were detected in the virus population with low frequency that may cause changes in transmission (in other species)… after evolution in dairy cattle.
“Continued transmission of H5N1 among dairy cattle increases the risk of infection and subsequent spread of the virus to human populations.”
Cattle herds on at least 36 farms in nine states tested positive (file photo)
In the article, published as a preprint in BioRxiv Although it has not been reviewed by other scientists, researchers analyzed nasal and milk samples from dozens of infected cows with confirmed infections from March to April of this year.
At least 491 mutations were detected in the sample, of which 309 were associated with “functional changes” of the virus.
This included mutations that may make the virus more pathogenic or more likely to cause infection, better adapted to mammals, and more capable of infecting new species.
Tests also suggested that the outbreak in livestock actually began in late 2023, about four months before it was first reported.
Researchers suggested that the virus had first jumped from birds to cows in the Texas Panhandle, and then spread among herds in the state, as well as herds in Kansas, Michigan and New Mexico, among others.
Outbreaks in several herds could not be linked to others, suggesting that some infected herds have not yet been detected with the virus.
Cases were also reported where the virus had spread from cows to wild birds, poultry, domestic cats and a raccoon.
At least 36 flocks in nine states have been infected with bird flu, data show, although experts warn it is likely more widespread.
There are also fears that the virus will spread to farm workers, and veterinarians say they have heard of many people who are sick on farms but are unwilling to get tested.
