Yorkshire – Credit Wikipedia
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Just over a year ago, HPAI H5N1 was detected in goats in the United States (see Minnesota BOAH Statement On HPAI H5N1 Infected Goat Kids), which was followed a few days later (March 25th) by the first HPAI detection in dairy cattle (see USDA Statement on HPAI In Dairy Cattle in Texas & Kansas Herds).
As we discussed a year ago, in A Brief History Of Influenza A In Cattle/Ruminants, while cattle had been experimentally infected in 2008, there had been little previous evidence of natural infection of these species. Since then, however, an August 2024 Preprint did report finding evidence of H5 antibodies in goats and sheep in Pakistan,.Overnight Defra ( the UK's Department for Environment, Food, and Rural Affairs) released a brief statement on that country's first HPAI H5 detection in livestock; in one domestic sheep in Yorkshire on a premises where H5N1 had been detected in captive birds.
First the official statement, after which a lengthier press release.
Confirmed findings of influenza of avian origin in captive mammals
Updated 24 March 2025
Sheep, March 2025
One domestic sheep (Ovis aries) tested positive for influenza of avian origin (H5N1) in March 2025. The case was identified following routine surveillance of farmed livestock on a premises in Yorkshire where highly pathogenic avian influenza (H5N1) had been confirmed in other captive birds. The single animal was a ewe with signs of mastitis but no other clinical signs. The milk was positive by polymerase chain reaction (PCR) and the blood tested positive for H5 antibodies.
All affected birds and the infected ewe were humanely culled to mitigate the risk of further disease spread. Further official testing of the remaining flock of sheep were all negative for the presence of avian influenza virus.
The full press release follows. I'll have a bit more after the break.
Influenza of avian origin confirmed in a sheep in Yorkshire
Influenza of avian origin (H5N1) has been confirmed in a single sheep in Yorkshire.
From: Department for Environment, Food & Rural Affairs and Animal and Plant Health Agency Published24 March 2025
The UK’s Chief Veterinary Officer has confirmed a case of influenza of avian origin (H5N1) in a single sheep in Yorkshire following repeat positive milk testing.
The case was identified following routine surveillance of co-located livestock on a premises where avian influenza had been confirmed in captive birds. Defra has introduced livestock surveillance on infected premises following the outbreak of avian influenza in dairy cows in the US.
The infected sheep has been humanely culled to enable extensive testing. Further testing in the remaining flock of sheep at the premises was undertaken by the avian influenza national reference laboratory at the Animal and Plant Health Agency Weybridge laboratory. No further infection with avian influenza virus was detected in the remaining flock and this remains a single case in a mammal detected on the premises.
While this is the first time this virus has been reported in a sheep, it is not the first time influenza of avian origin has been detected in livestock in other countries. There is no evidence to suggest an increased risk to the nation’s livestock population.
However, the UK Chief Veterinary Officer is urging all livestock keepers to remain vigilant to the clinical signs of avian influenza following recent outbreaks. All keepers must maintain good biosecurity which is essential to protect the health and welfare of their animals and critical to preventing the further spread of disease in the event of an outbreak.
In line with the UK’s international reporting requirements, this case will now be reported to both the World Organisation for Animal Health (WOAH) and the World Health Organisation.
UK Chief Veterinary Officer Christine Middlemiss said:
“We have confirmed the detection of influenza of avian origin (H5N1) in a single sheep on a farm in Yorkshire. Strict biosecurity measures have been implemented to prevent the further spread of disease.
“While the risk to livestock remains low, I urge all animal owners to ensure scrupulous cleanliness is in place and to report any signs of infection to the Animal Plant Health Agency immediately.”
The UK Health Security Agency (UKHSA) has said that avian influenza is primarily a disease of birds and the risk to the general public’s health is very low, but people should not touch any dead or sick wild birds they find.
The Food Standards Agency advises that properly cooked poultry and poultry products, including eggs, remain safe to eat and avian influenza poses a very low food safety risk to UK consumers since the H5N1 virus is not normally transmitted through food.
Dr Meera Chand, Emerging Infection Lead at the UK Health Security Agency, said:
“Globally, we continue to see that mammals can be infected with avian influenza A(H5N1).
“However, current evidence suggests that the avian influenza viruses we’re seeing circulating around the world do not spread easily to people – and the risk of avian flu to the general public remains very low.
“UKHSA will continue to monitor the situation closely alongside Defra, DHSC, Animal and Plant Health Agency and Food Standards Agency.
“UKHSA has established preparations in place for detections of human cases of avian flu and will respond rapidly with NHS and other partners if needed.”
Robin May, Chief Scientific Adviser at the FSA said:
“We are working very closely with Defra, UKHSA and Food Standards Scotland following the discovery of avian influenza virus in a sheep in the UK. Our advice remains that bird flu poses a very low food safety risk to UK consumers since the H5N1 virus is not normally transmitted through food.
“We continue to monitor the situation closely and will assess any emerging information to continue to ensure UK food is safe.”
What you can do
Avian influenza is notifiable in all poultry and other captive birds and Influenza of avian origin is notifiable in both kept and wild mammals. If you suspect your animals are infected with avian influenza virus you must report it to the APHA immediately by calling:
· 03000 200 301 in England
· 0300 303 8268 in Wales
· Contacting your local Field Services Office in Scotland
Failure to do so is an offence.
We have published a case definition for influenza of avian origin to support decisions around reporting suspicion, together with further information on how we monitor the risk of influenza of avian origin in wild mammals gov.uk.
At this point there is no word on the genotype, and nothing has been posted on the WOAH WAHIS dashboard.
While Germany's FLI published a report last summer on the successful Experimental Infection Of Dairy Cows With European H5N1 Virus - and urged increased vigilance - most countries outside of the United States have not adopted routine surveillance or testing of livestock for H5N1 because the B3.13 genotype has only been detected in the United States.
Last October the UK released the following risk analysis. Since then, of course, we've seen cattle infected by the D1.1 genotype as well.
Research and analysis
HAIRS risk statement: Avian influenza A(H5N1) in livestock
Updated 24 October 2024
Risk statement
This risk statement provides a qualitative description of the zoonotic risk avian influenza (AI) A(H5N1) clade 2.3.4.4b genotype B3.13 would present to people in contact with animals in the UK, and highlights evidence gaps and recommendations for mitigating the risk of zoonotic transmission.
Although new detections have been reported in dairy cattle, cats, alpacas and humans in the USA, and additional information has become available since the last risk statement (published in May 2024), the HAIRS group determined that this remains at most a very low risk. This is because there is no evidence to suggest AI A(H5N1) clade 2.3.4.4b genotype B3.13 is present in the UK. The HAIRS group will continue to monitor the situation and update this risk statement if any substantial developments arise.
Between today's announcement, the FLI's 2024 assessment that European genotypes could infect cattle, and the recent detection of genotype D1.1 in dairy cattle in Nevada and Arizona, we can probably expect some sort of update from the HAIRS group in the days or weeks ahead.
Stay tuned.
