by Britain is in the midst of the biggest bird flu outbreak in history and the virus has now spread to mammals, authorities have discovered.
Bird flu has killed millions of birds worldwide, both wild and captive, and the UKHSA has reported that four otters and five foxes have died after contracting the virus.
These animals are known to eat carrion, and the mammals are believed to have become infected after eating a dead bird that died from avian influenza.
Professor Ian Jones, a virologist at the University of Reading, said it was “not too surprising” that some mammals have contracted the virus from birds because it is now widespread.
However, there is some concern that the virus will detect genetic mutations after entering mammals.
But while some early signs have piqued the interest of scientists, they caution that a sustained and widespread infection among mammals, including humans, would require much more significant genetic changes to overcome the natural barriers that prevent bird flu from infecting all animals. .
The UK is now expanding its surveillance of avian influenza in mammals to better track any changes in the virus.
However, health officials say there is no evidence that mammals in the UK are passing the virus between them and the threat to human health remains low.
One strain of avian influenza, H5N1 2.3.4.4b, is dominant and is causing the current outbreak that is incredibly virulent and deadly in birds.
There have been previous spills of bird flu in mammals, but they are rare and only occur when there is a large amount of bird flu in circulation.
Nine positive cases in mammals
Analysis of 56 mammals by the UK Health Security Agency (UKHSA) and the Animal and Plant Health Agency (APHA) found nine positive cases in mammals.
In Spain, news broke last month that bird flu had infected a mink farm and was passing from one mammal to another, which the UKHSA recognized as “of serious concern”.
Professor Munir Iqbal, head of the Pirbright Institute’s Avian Influenza Group, told The Telegraph: “There is a mutation called PB2 E627K that occurred very quickly after animals became infected and helps the virus replicate better in mammals. .
“But the fact that it can replicate better does not mean that the virus also has the ability to transmit to a new host and make a chain of transmission. It’s just that, in that infected host, it can help to replicate better.”
“At present, there are no indicators of an increasing risk to human health,” the UKHSA said as it expanded its surveillance of mammals and research into bird flu.
They caution that because of the large number of birds catching and dying from the virus at a time when the risk of a human contracting it is greatest, such cases are still “rare.”
Scientists from Spain and the UKHSA have identified two important mutations in the bird flu virus related to infection in mammals.
The T271A mutation found on the Spanish mink farm is “uncommon” and “may have implications for public health,” the scientists from Spain’s Ministry of Agriculture, Fisheries and Food said.
“Indeed, the same mutation is present in the avian-type PB2 gene of the 2009 swine-origin pandemic influenza A(H1N1) virus.”
The UKHSA warns that PB2 mutations “may imply that this virus has a propensity to cause zoonotic infections.”
But after analyzing all the available data, including the mink study, the APHA concludes that there is no “widespread adaptation of this virus in mammals.”
Avian influenza is now classified as level three, on a scale of one to five, meaning there is “evidence of viral genomic changes that provide an advantage for mammalian infection” but no sustained transmission.
