Britain is on red alert for bird flu after two poultry workers tested positive for the killer virus.
Health chiefs today revealed they are monitoring the threat ‘very carefully’ amid ever-growing fears another human pandemic is lurking around the corner.
No signs of human-to-human transmission have yet been detected in the UK.
Officials have already hunted down close contacts of the two infected workers in efforts to contain any potential outbreak.
Neither of the pair — who worked on the same farm in an undisclosed location — suffered any symptoms of the illness. Both have since tested negative after being diagnosed earlier this month.
The new cases come after Alan Gosling (pictured), a retired engineer in Devon, caught the virus after his ducks, some of which lived inside his home, became infected in 2022
UK scientists tasked with developing ‘scenarios of early human transmission’ of bird flu have warned that five per cent of infected people could die if the virus took off in humans (shown under scenario three). Under another scenario, the scientists assumed 1 per cent of those infected would be hospitalised and 0.25 per cent would die — similar to how deadly Covid was in autumn 2021 (scenario one). The other saw a death rate of 2.5 per cent (scenario two)
Professor Susan Hopkins, chief medical advisor at UK Health Security Agency (UKHSA), told the BBC Radio 4’s Today programme: ‘Clearly this is an ongoing risk that we need to monitor and watch for very carefully and understand how transmission may occur.’
Both workers have since ‘become negative on PCR swabs’ and it remains ‘uncertain whether they were a true infection’, she added.
A true infection occurs if ‘the virus was replicating in their nose’ and therefore posed a risk to others.
The virus could otherwise have sat ‘in the back of the nose from contamination,’ she said.
Read more: Two Brits are struck down with bird flu but health chiefs insist there’s no proof killer virus is spreading between humans
Professor Hopkins told the programme: ‘These are people who are working in very close contact and the proximity with infected birds on infected farms.
‘So there will be a lot of dust and a lot of potential virus fragments in the air, but also on the ground, on their clothing as they’re working in this environment.
‘They wear a lot of PPE to prevent them from getting infected.
‘But there is always still a risk that this virus and the contaminants from the environment can get under the nose and therefore we can detect bird flu when we do swabs from that.’
She added: ‘We are testing the contacts of individuals, we are offering tests at least to the contacts of individuals.
‘We will continue to do that as part of our surveillance.’
H5N1 — the avian influenza strain behind the current outbreak sweeping the world, considered the biggest ever — does not transmit easily between humans.
But mutations to the virus that makes mammal-to-mammal transmission easier could change that, some experts fear.
Globally, fewer than 900 human cases of H5N1, which kills close to 50 per cent of everyone it strikes, have ever been recorded.
The virus is usually picked up through close contact with an infected bird, whether dead or alive.
Like other forms of flu, humans can get infected if the virus gets into their eyes, nose, mouth or is inhaled.
But with bird flu, this usually occurs in people who spend a lot of time with infected creatures, such as bird handlers.
A spate of human bird flu cases have emerged in the early parts of 2023.
Earlier this year, a Cambodian man and his daughter were diagnosed with H5N1.
Their cases sparked international concern, with many experts fearing the infection was proof the virus had mutated to infect people better after tearing through the world’s bird population.
Further testing found the Cambodian family did not have the H5N1 strain rapidly spreading among the world’s wild birds — but instead a variant known to spread locally in the Prey Veng province they resided in.
Over 700 confirmed cases of H5N1 have been detected among wild birds in England since September 2022, according to the UKHSA. Pictured above, a bird flu outbreak in February in Queens Park, Heywood, Rochdale
Both the British workers were spotted through routine testing of people came into contact with infected birds, the UKHSA confirmed yesterday. Neither was named.
The two individuals ‘were tested repeatedly over a period of time’, Professor Hopkins told the Today programme.
‘They manifested no symptoms which is really good and they didn’t transmit to anyone else,’ she added.
‘We don’t think this increases the risk to the population across the UK at present.’
Health officials said one of the persons infected likely tested positive for bird flu after inadvertently inhaling infected material, like faeces, from diseased animals.
But they added how the second person had come into contact with the virus was currently unclear.
There has only ever previously been one case of a British person becoming infected with H5N1 since the ongoing outbreak took off in October 2021.
Read more: Fresh pandemic fears as virologists discover bird flu spreads ‘efficiently’ in ferrets – sparking warning that strain could be 100 TIMES worse than Covid if it ever jumps to humans
Alan Gosling, a retired engineer in Devon who kept ducks at home, caught the virus in early 2022 after his ducks became infected.
He later tested negative while he was quarantined for nearly three weeks.
All 160 of Mr Gosling’s ducks — including 20 that lived inside his home — were culled after he tested positive.
Government advisor, Professor Ian Brown, the director of scientific services at the Animal and Plant Health Agency (APHA), said: ‘Deep surveillance programmes of personnel in close contact with infected poultry are insightful to understand what could happen.
‘To date out of the reported detections in humans it is clear that careful investigation and interpretation is required.’
However, he added: ‘Detection by PCR alone does not necessarily prove active infection and supports the virus still remains strongly avian in its tropism.
‘But programmes such as those being deployed in Great Britain are valuable to gain better understand of the true risk these viruses currently pose to human health.
‘The one health joined up approach being applied in Great Britain sets best international practice for vigilance.’
Current advice from the UKHSA states the risk to public health from the virus is very low.
People are advised not to touch or pick up any dead or visibly sick birds that they find.
In the UK, there have been 183 confirmed wild cases of H5N1 since October 2022.
British farms have already faced tough, lockdown-esque biosecurity rules in efforts to combat the deadly disease.
A housing order keeping birds indoors — even those reared as free range — to avoid contact with wild birds was only lifted last month.
Asked this morning if the mandatory housing order for bird should be returned if further human cases are detected, Professor Hopkins said: ‘I think we’re seeing much less detections in farms than we saw pre-winter and even last summer and therefore the overall risk to poultry on our farms is much less than it was before.’
Some nations, including China, have been vaccinating birds against the H5N1 strain for years.
Birds are vaccinated either via an injection into the egg or a spray onto chicks when they are still in boxes.
Under UK health policy however, vaccinating chickens is currently illegal.
APHA, an arm of DEFRA, is reviewing the bird flu risk to humans every week.
The government agency has currently set the threat level to level three, given there is ‘evidence’ of changes in the virus genome that could trigger ‘mammalian infection’, it said.
Any ‘sustained’ mammal-to-mammal transmission of the pathogen would raise the threat level to four, while human-to-human would push it to five.
British scientists have predicted the virus could kill one up to one in 20 people it infects, if it ever manages to take off in humans.
Bird flu outbreak: Everything you need to know
What is it?
Avian flu is an infectious type of influenza that spreads among birds.
In rare cases, it can be transmitted to humans through close contact with a dead or alive infected bird.
This includes touching infected birds, their droppings or bedding. People can also catch bird flu if they kill or prepare infected poultry for eating.
Wild birds are carriers, especially through migration.
As they cluster together to breed, the virus spreads rapidly and is then carried to other parts of the globe.
New strains tend to appear first in Asia, from where more than 60 species of shore birds, waders and waterfowl head off to Alaska to breed and mix with migratory birds from the US. Others go west and infect European species.
Which strains are currently spreading?
H5N1 and H3N8.
So far the virus H5N1 has been detected in some 80million birds and poultry globally since September 2021 — double the previous record the year before.
Not only is the virus spreading at speed, it is also killing at an unprecedented level, leading some experts to say this is the deadliest variant so far.
Millions of chickens and turkeys in the UK have been culled or put into lockdown.
But earlier this year, on March 27, the World Health Organization (WHO) was also informed that a Chinese woman had become the first person to ever die from the H3N8 strain.
The 56-year-old woman from the southern province of Guangdong was the third person known to have been infected with the H3N8 subtype of avian influenza, according to the WHO.
Although rare in people, H3N8 is common in birds, but it causes little to no sign of disease.
It has also infected other mammals.
Can bird flu infect people?
Yes, but only 873 human cases of bird flu have been reported to the World Health Organization since 2003.
The risk to people has been deemed ‘low’.
But people are strongly urged not to touch sick or dead birds because the virus is lethal, killing 56 per cent of people it does manage to infect.