News that a Texan had been infected with H5N1 bird flu on Monday added a worrying wrinkle to a global outbreak that is edging closer to humans.

The patient was a dairy farmer and caught the virus from an infected cow, making them the second American to be infected after a person in Colorado in 2022.

While there is no sign of person-to-person spread — a development that would signal the start of a human epidemic — experts say the ease with which the strain is jumping between species raise the risk of it evolving to infect us more easily.

This variant of H5N1 has been detected in almost every corner of the globe, from the barren Antarctic to the depths of the ocean, since emerging in 2020. But it is the developments that are a little closer to home that are causing concern.

It has been in US poultry farms for years, goats and now cows (not to mention a pet dog in Canada). spoke to seven infectious disease experts and virologists who have been tracking bird flu H5N1 for years about what the development in Texas means.

Tests revealed that an unknown number of cows have tested positive for bird flu Type A H5N1 in Texas, Kansas and New Mexico. Iowa is currently ‘monitoring the situation’ as it is also a dairy-heavy state. It comes after a goat in Minnesota tested positive last week. Bird flu has also been found in foxes, bobcats, striped skunks, raccoons and coyotes since the 2022 outbreak

Dr Leonard Mermel, an infectious diseases expert in Rhode Island, warned repeat infections in mammals raised the risk of the virus gaining harmful mutations. Dr Diego Diel, from Cornell University, warned that cases were highlighting bird flu’s ability to spill over into mammals

Dr Aaron Glatt, an infectious diseases expert at Mount Sinai, New York, warned: ‘It is absolutely true that H5N1 has the potential to cause a pandemic.

‘People who work with these animals do need to be careful. 

‘The more that this virus is spread, the more likely it is that it could become a strain that could mutate and start to spread from human-to-human.’

The H5N1 spreading across the world emerged in 2020 after a bird was infected with both a bird flu from domestic poultry and a virus from wild birds.

During the infection, the two viruses met in the same cell and swapped genes — in a process scientifically termed re-assortment — to create the new virus that now had multiple attributes which made it better at infecting bird cells.

It quickly spread globally, with the first cases identified in Europe — before infections also being detected in Africa, the Middle East and Asia. 

Experts fear that infections in cattle and other mammals could raise the risk of the virus adapting to spread in humans (stock image)

Dr Leonard Mermel, an infectious diseases expert at Brown University, in Rhode Island, said the fact the disease was spreading in mammals ‘raised the risk’ of the virus evolving to infect humans.

‘Viruses have multiple mutations in every replication cycle [each time they make copies of themselves],’ he said.

‘Each time that process occurs, where the viruses replicate, there may be many, many mutated viruses that leave [an infected] cell to infect other cells.

‘One could, by chance, have a mutation allowing it to bind to these mammalian cells that would then allow it to transmit from mammal-to-mammal [and potentially human-to-human].’

While jumping between species carries the risk of a freak mutation, experts are particularly concerned about the virus getting into one population: pigs.

Pigs have the same receptors on their lungs — called alpha 2, 6 — as humans and they can harbor both bird and human viruses simultaneously.

Infections in pigs would be a warning sign that the virus has developed a mutation allowing it to bind to this receptor and a sign it could spread to humans.

There is also a risk of a pig being infected with a human and bird flu virus at the same time which could swap genes to make a new and potentially more dangerous virus.

In 2009, a swine flu outbreak occurred when a pig was infected with a human and bird flu virus simultaneously. This allowed the bird virus to use the human virus blueprint to start spreading between humans. 

The outbreak led to 60million swine flu infections in humans in the US alone, nearly 300,000 hospitalizations and an estimated 12,400 deaths.

John Fulton, a pharmaceutical industry expert working on a bird flu vaccine, told ‘I think we are way past “if” and well on our way to when…’ when asked if this H5N1 strain would cause an outbreak in humans.

He has been working on developing a vaccine against bird flu for years, because the seasonal vaccines used to protect against human flu does not offer protection.

He is now around 18 months away from creating a new shot for poultry.

Even the experts who aren’t too concerned about the case in Texas believe it could be symbolic of the virus beginning to become more dangerous to humans.

Dr Michael Osterholm, who has been tracking bird flu for decades, said: ‘These cases are of concern and we will be sure to follow what is happening with them.

‘We will have avian influenza pandemics, there is no question.’

Adding caution, he said: ‘But we are seeing no cases in swine and swine are the real bridge species for us because they have the same receptor sites in the lungs.’

Dr Bill Schaffner, an infectious diseases expert at Vanderbilt University in Tennessee, said: ‘[Bird flu cases] happen periodically with humans, but you rarely get human-to-human transmission.

‘The genetic part of the virus that would allow it to transmit readily from human-to-human is still missing.’ 

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