THE UK is to increase its surveillance of cases of avian influenza as well as the genome itself.

The Animal and Plant Health Agency (APHA) has detected nine positive cases of mammals with AI since 2021.

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The agency has tested 66 mammals over that period according to a report in the BBC, including seals, and the positive cases were in otters and foxes.

Prof Ian Brown, APHA’s director of scientific services, told the BBC: “A sick or a dead wild bird contains an awful lot of virus.

“So scavenging mammals that will be opportunistic and predate on dead or sick birds will be exposed to very large quantities of virus.

“That gives a possibility for the virus to enter a host population that it doesn’t normally maintain in.”

He added the UK’s national avian flu taskforce would now ramp up its surveillance of cases in mammals and genome analysis of the virus.

Dutch study

While surveillance may be increasing, recently published research from the Netherlands suggests the virus does not spread between mammals.

Despite that, a zoonotic mutation was found, a sign that the virus is adapting to a new host, according to Nancy Beerens, head of the Dutch National Reference Laboratory for Avian influenza.

In the Netherlands over the winter of 2021/2022 foxes, polecats, an otter and a badger tested positive for avian influenza.

They were noticed because of abnormal behaviour with neurological symptoms. When tested, the virus was particularly prevalent in the animals’ brains, with throats, nose and rectum swabs often testing negative.  

Zoonotic mutation

In some animals, a zoonotic mutation (PB2-E627K) was detected in analysis of mammalian viruses.

This allows the virus to multiply better in mammals. The mutation was not found in wild bird viruses. However, multiple mutations are needed before a virus can spread between mammals or to humans.

An HPAI H5N1 infection was recently detected at a mink farm in Spain, where there was concern over the possible virus spread between the animals. 

“The mutations found on the farm were not detected in the wild mammals in Wageningen Bioveterinary Research studies.

“Genetic analysis of the wild mammalian viruses showed that they are not closely related. There is no evidence of spread of the virus between these mammals.

“The mammals have become infected independently of each other by eating infected wild birds,” added Ms Beerens.