Bird flu can infect horses without causing any symptoms, according to new research, raising fears that the virus could be spreading undetected.

It’s another twist in the emerging threat of the H5N1 virus, widely seen as the most likely cause of the next pandemic.

Scientists at the University of Glasgow found antibodies to the virus in blood samples taken from horses living in Mongolia. Their results have been published in the journal Emerging Infectious Diseases.

Image:
The HPAI H5N1 virus. File pic: iStock

Professor Pablo Murcia, who led the research, told Sky News that the finding suggests horses worldwide could be vulnerable in areas where bird flu is present – and they could pass on the virus to humans.

“It’s very important, now we know these infections can occur in nature, that we monitor them to detect them very rapidly,” he said.

“Horses, like many other domesticated animals, live in close proximity to humans and if this virus was to establish in horses the probability of human infection increases.”

The team at the Medical Research Council-University of Glasgow Centre for Virus Research also believe horses could be a mixing bowl for new strains of flu.

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It’s already known that they can be infected with equine flu, caused by the H3N8 virus. But if a horse is simultaneously infected with H5N1, the viruses could swap genetic material and evolve rapidly.

The H5N1 virus has been around for several decades, largely causing outbreaks in poultry. But in recent years a new variant has spread worldwide with migrating birds and has repeatedly jumped species to infect mammals.

The virus is spreading in cows in the US, with more than 700 dairy herds in 15 states infected, according to the Centers for Disease Control.

Almost 60 farm workers have been infected, though so far all have had mild symptoms.

Scientists are concerned that the virus is developing mutations that would help it survive in mammalian cells and have criticised the slow response of US authorities.

Dr Tulio de Oliveira, the director of the Centre for Epidemic Response and Innovation in South Africa, who first detected the Omicron variant in the COVID pandemic, said he is watching events in the US with dread.

“The last thing that they would need at the moment is another pathogen that evolved and mutated,” he told Sky News.

“If you keep H5N1 circulating for a long time and across different animals and in humans, you give the chance that that can happen.

“They do not need another potential pandemic.”

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US authorities are bringing in new rules on testing of raw milk, which can contain live virus.

According to the UK Health Security Agency the virus is highly unlikely to affect cattle in Britain and the risk to the public is low.

But an order has been placed for five million doses of a vaccine against the H5 family of viruses if bird flu begins to spread in humans.