Should I be worried about bird flu? Separating fact from fiction

Yahoo

29-01-2025

If you're battling a fever, aching muscles and a pounding headache, your first thought may be that you have caught the flu. But for one person in the West Midlands, their flu-like symptoms turned out to be avian influenza.
This virus was detected recently in the unidentified farm worker, who is the seventh person to test positive in the UK since 2021 and only the second to have any symptoms. They are said to be well and are being monitored at a specialist infectious disease hospital ward, according to the UK Healthy Security Agency (UKHSA).
The risk to the public of catching the virus is 'very low', according to health officials and all people who have been infected in the UK have been in close contact with birds.
Yet although there has not yet been any evidence of person-to-person transmission, this is the big worry and 'is one of the most feared infectious disease threats we face', says Prof Andrew Preston from the Milner Centre of Evolution at the University of Bath.
What is bird flu?
Can humans get bird flu?
Can bird flu kill humans?
How do you catch bird flu?
The symptoms
What happens if I become infected?
Bird flu, also known as avian flu, is an infection in birds caused by the influenza A virus.
It has an almost 100 per cent fatality rate in birds. Since October 2021, when the first case of the highly pathogenic influenza strain H5N1 was confirmed in the UK, there have been more than 280 million poultry birds deaths globally, according to data from the World Animal Health Information System.
Influenza A (H5N1) is the strain that is currently dominant and spreading, though other subtypes, including A (H7N9) have also been detected.
While the name may make it seem like the infection only affects birds, this is incorrect. It is possible for humans, as well as other animals, to become infected.
In the UK, there have been seven confirmed infections in people since 2021.
All cases have been among people who have had close and prolonged contact with a large number of infected birds. For example, Alan Gosling, a retired duck expert, caught the virus in early 2022 after his pet ducks became infected.
Bird flu has also been detected among mink, foxes, otters and seals. In recent months, it has spread among dairy cows in the United States and people working on those farms have been infected.
While bird flu has killed a huge number of birds, it can also still be fatal in humans.
No one has died in the UK as a result of the virus but, in January 2025, the US recorded its first death among a person infected with the A(H5N1) strain.
Worldwide, more than 950 bird flu infections in humans have been reported to the World Health Organization and half of those have resulted in death.
In cases that are fatal, the virus causes severe respiratory distress syndrome, Prof Preston explains. 'The virus starts to damage your respiratory cells but the [infected person's] response is so extreme that it sets off a cytokine storm [when the body releases a large number of cytokines].'
Too many cytokines (which direct immune cells toward the site of an infection) forces the immune system into overdrive. Ultimately, this can lead to organ failure and death.
The only way you can catch avian flu is through close contact with infected birds, such as touching these birds, their droppings or bedding. 'We need to breathe in the particles to become infected,' Prof Preston explains.
Theoretically, it is possible, though unlikely, that a bird could catch flu from a human, he says. 'It would require someone with active influenza to then go out and interact with a bird,' he adds.
Scientists are concerned that bird flu may eventually mutate so that it can readily spread among people – something it cannot currently do.
This is because birds and humans have very different molecules along their respiratory tract and bird flu currently struggles to bind strongly to the human respiratory system.
'One concern would be an evolution of avian flu to become better at binding to human molecules,' he says. This would most likely occur by the virus spreading to an intermediary species, such as a pig, as their respiratory tract contains molecules found both in humans and birds. In this scenario, pigs become a perfect mixing vessel and could transmit a mutated bird flu to humans, which is better able to spread among people, Prof Preston warns.
Another way that avian influenza could begin spreading among humans is if a person who is already infected with regular flu becomes infected with bird flu, he says. In this case, the two different flu viruses could recombine and produce a new one that can pass from person to person. 'That's the big Armageddon scenario,' he says. 'And we know it's entirely feasible for it to happen. We think it would then spread very widely and very rapidly.'
The latest evidence from the UKHSA is that the risk of avian flu remains very low.
While regular flu and bird flu are different viruses, that doesn't mean their symptoms vary.
In fact, bird flu symptoms overlap with those of regular flu and can include: a high fever, aching muscles, a headache, a cough or shortness of breath.
However, bird flu has caused no symptoms or only mild symptoms among people who have become infected in the UK.
A test is required to confirm whether symptoms are caused by regular flu or bird flu, Prof Preston explains.
The risk of catching bird flu among the general public is very low, though it is slightly higher among people who are in regular contact with poultry.
The UKHSA advises people not to touch or handle wild birds on their droppings and to stay at least two metres away from wild birds. 'If you see a dead bird, don't approach it or handle it,' says Prof Preston.
It is incorrect that you need to avoid poultry products to reduce the risk of catching bird flu, he says. 'The virus doesn't get into eggs and is not going to find its way into meat,' he says.
Theoretically, even if it was present on a piece of meat in your fridge, the virus dies quickly in response to heat, so would be eliminated during cooking, Prof Preston adds.
Once the UKHSA has confirmed a human bird flu case, the patient may be told to remain at home or admitted to a High Consequence Infectious Disease unit, which are hospitals equipped to manage and monitor contagious infections.
The infected patient, and those they have had close contact with, may be given antiviral medicine, such as oseltamivir (Tamiflu) or zanamivir (Relenza). These drugs reduce the severity of an infection, prevent complications and improve the chance of survival.
However, it is unclear if antivirals would be dished out if there was a large-scale avian flu outbreak in people, Prof Preston says. 'As soon as you start to use antivirals, you run the risk of selecting a variant that is resistant to them, which will make them less effective.'
There is no bird flu vaccine and the seasonal flu jab, offered to the over-65s and vulnerable groups each year, is not expected to protect against bird flu.
However, there may be a vaccine in the near future. Prof Preston notes that vaccine prototypes have been developed for the current H5N1 bird flu strain in circulation.
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