Bird flu can infect horses asymptomatically, recent research suggests, prompting concerns that the virus could have found ways to spread undetected.
H5N1, the technical name for the bug which has killed millions of birds directly and led to the culling of millions more to prevent outbreaks, is a growing worry for scientists.
Some believe it is the bug most likely to drive the next pandemic, with specialists closely monitoring for any mutations that could make it a greater risk to humans.
Research from scientists at the Medical Research Council-University of Glasgow Centre for Virus Research offers a striking insight into the challenges of keeping it in check, with the discovery that horses in Mongolia had antibodies to bird flu.
Professor Pablo Murcia, who led the research, says their findings suggest that horses all around the world could be at risk in regions with a prevalence of the avian virus.
He also believes they could potentially infect humans with H5N1, Sky News reports.
“It’s very important, now we know these infections can occur in nature, that we monitor them to detect them very rapidly,” he told the outlet.
“Horses, like many other domesticated animals, live in close proximity to humans and if this virus was to be established in horses the probability of human infection increases.”
However, no outbreaks of respiratory disease were reported in the herds the team looked at according to the research, published in the journal Emerging Infectious Diseases in early December, suggesting the cattle that tested positive for H5N1 antibodies had infections without symptoms.
But it is feared that simultaneous infections of both equine and bird flu could see the viruses exchanging genetic material and quickly evolving.
For several decades, bird flu outbreaks were largely limited to poultry, though in recent years a new variant has seen it spread globally via migrating birds and is now infecting mammals.
It comes as scientists are closely monitoring recent outbreaks in US dairy cattle across various states, which have infected dozens of farm workers.
US authorities are bringing in new rules on testing of raw milk, which can contain live virus. The UK Health Security Agency (UKHSA) says the virus is highly unlikely to affect cattle in Britain and the risk to the public is low.
Bird flu infections in humans remain rare, and there is currently no evidence that it can transmit from person to person, as per Nature.
A Government spokesperson said: “We continually update our pandemic planning as concerns about infectious diseases emerge and recently announced the purchase of more than five million doses of human H5 influenza to ensure we are prepared.”
Meanwhile, the UK government announced in early December that a contract had been agreed for more than five million doses of human H5 influenza vaccine to boost the country’s resilience in the event of a possible H5 influenza pandemic.
“The procurement will strengthen the UK’s preparedness for a H5 influenza originated pandemic by ensuring that vaccines are immediately available, while a pandemic specific vaccine is made ready,” the press release said.
“The UK Government already has an advance purchase agreement for pandemic vaccines if or when they are needed, that would be tailored to combat the specific pandemic flu strain identified at the time.”
