Britain is in the midst of its biggest ever outbreak of bird flu and the virus has now spread to mammals, according to authorities.
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 it is believed that the mammals became infected after scavenging on a dead bird killed by bird flu.
Professor Ian Jones, a virologist at the University of Reading, said it is “not too surprising” that some mammals have caught the virus from birds because it is so rampant at the moment.
However, there is some concern that the virus picked up genetic mutations after entering the mammals.
But while some early signs have pricked the ears of scientists, they warn that persistent and widespread infection between mammals, including humans, would require much more significant genetic changes to overcome the natural barriers. bird flu from all animals to overcome its infection.
The UK is now expanding its bird flu surveillance to better track any changes in the virus.
However, health officials say there is no evidence that mammals in the UK are currently passing the virus among themselves and that the threat to human health remains low.
One strain of bird flu, H5N1 2.3.4.4b, is dominant and is driving the current outbreak which is extremely virulent and deadly in birds.
Bird flu has occurred before in mammals but they are rare and only occur when there is a large bird flu in circulation.
Nine positive cases in mammals
An 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.
It emerged in Spain last month that a mink farm was infected with bird flu and was being passed from mammal to mammal, which the UKHSA acknowledged was a “serious concern”.
Professor Munir Iqbal, head of the Avian Influenza Group at the Pirbright Institute, told the Telegraph: “There is one mutation called PB2 E627K which occurs very quickly after the animals are infected and it helps the virus to replicate better in mammals.
“But just because it can replicate better does not mean that the virus is also capable of transmission to a new host and chain of transmission. It’s just that, in that infected host, it can help replicate better.”
“Currently, there are no indicators of increased risk to human health,” the UKHSA said as it expanded its mammal surveillance and bird flu investigation.
They warn that due to the large number of birds that are catching and dying from the virus at the moment when the risk of catching it is the highest, such cases are still “rare”.
Scientists in Spain and the UKHSA have identified two mutations in the bird flu virus most prominent in infecting mammals.
The T271A mutation found on the Spanish mink farm is “rare” and “may have implications for public health”, scientists from the Spanish Ministry of Agriculture, Fisheries and Food said.
“In fact, the same mutation is present in the avian-like PB2 gene of the 2009 swine-origin pandemic influenza A(H1N1) virus.”
The UKHSA warns that the PB2 mutations “may suggest that this virus has a tendency to cause zoonotic infections”.
But after looking at all the available data, including the mink study, the APHA has concluded that there is no “widespread adaptation of this virus in mammals”.
Avian flu is now classified as level three, on a scale of one to five, meaning there is “evidence of viral genomic changes that confer an advantage to infecting mammals” but no sustained transmission.