I News 10 bush dogs at a zoo in England have caught and likely died from the H5N1 virus, suggesting some limited transmission between animals.
Scientists are investigating the possibility that bird flu was transmitted among a pack of bush dogs at a zoo in England.
Ten bush dogs at the unnamed zoo died in what is being described as an isolated event last November. The H5N1 avian influenza virus was detected in the dead animals through retrospective sampling, the UK Health Security Agency said.
While mammal to mammal transmission has not been confirmed in the dogs, it is one line of investigation. There is a possibility that the dogs caught the virus through infected birds fed to them by zookeepers.
In its updated risk assessment for bird flu, the UKHSA said the UK is currently at Level 3, meaning there is “limited mammalian transmission”.
This is a change in wording from the last assessment, when the alert level was described as “changes in the virus genome that could lead to mammal-to-mammal transmission”.
However, the UKHSA insisted the level of risk had not changed. A spokesperson said: “The risk to human health has not changed. As previously, there is low confidence evidence of limited transmission in mammals, but there is no current evidence that this risk is changing.”
A previous assessment defined the risk as spillover infections in mammals with non-sustained transmissions between mammals, and the scale of risk had been changed to provide more granular detail, a source said.
But scientists are on high alert for transmission between animals after incidents of mass infections and deaths of mammals in areas around the world, including farmed mink in Spain, seals in the Caspian Sea and sea lions in Peru.
There have been 23 deaths of wild mammals in the UK since the current outbreak of the highly infectious H5N1 virus began 18 months ago, including two dolphins, mainly due to isolated cases of animals scavenging on infected dead birds. The 10 bush dogs would take the total of wild and captive mammals who have died to 33.
Government scientists insist there is no change to the risk to human health, which is classed as very low.
Scientists at the UKHSA and the SPI-M group, which produced modelling of the covid pandemic for the government, have also revealed different scenarios for what would happen in a human pandemic of bird flu.
While there is still no evidence of human-to-human transmission, the UKHSA said it wanted to prepare for the emergence of novel influenza viruses.
The current risks assessment says the H5N1 virus can “successfully infect mammals and humans with high levels of direct exposure (for example, scavenger mammalian species, humans working closely with birds)”. There have been only seven cases of bird flu in humans since October 2021.
It adds: “Polymerase basic protein (PB2) mutations associated with mammalian adaptation, including E627K, are seen in mammalian infections. There is evidence of transmission in farmed mink and possible, though unconfirmed, transmission in populations of seals and sea lions.”
Dr Meera Chand, Deputy Director at UKHSA, said: “The latest evidence suggests that the avian influenza viruses we’re seeing circulating in birds do not currently spread easily to people.
“However, viruses constantly evolve, and we remain vigilant for any evidence of changing risk to the population. It is right that we prepare for the emergence of novel influenza viruses and we are working with partners to ensure that we have the tools and capabilities in place for these and other emerging infections.”