LONDON — The United Kingdom reported the first confirmed case of avian influenza found in sheep, announced the country’s Department for Environment, Food & Rural Affairs (DEFRA) on March 24.

The United Kingdom’s Chief Veterinary Officer Christine Middlemiss confirmed that H5N1 was detected in a single sheep in Yorkshire following repeat milk testing, similar to the United States’ National Milk Testing Strategy.

“Strict biosecurity measures have been implemented to prevent the further spread of disease,” she said. “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 and Plant Health Agency immediately.” 

The infected sheep was located on the premises where highly pathogenic avian influenza (HPAI) had infected a flock of birds previously. The new sheep case was discovered through routine surveillance of co-located livestock in the affected area.

DEFRA introduced livestock surveillance on infected premises as a response to the H5N1 outbreak among dairy cows in the United States, which began in March 2024.

The agency said the infected sheep has been culled so that extensive testing may be conducted. The remainder of the flock of sheep was tested at the Animal and Plant Health Agency Weybridge laboratory, but no other signs of the virus were detected.

The case has been reported to the World Organization for Animal Health (WOAH) and the World Health Organization. 

Just as the United States’ Centers for Disease Control and Prevention (CDC) has maintained throughout the duration of the HPAI outbreak, the UK Health Security Agency (UKHSA) said the risk of the disease to the general public is low.

“Globally, we continue to see that mammals can be infected with avian influenza A(H5N1),” said Meera Chand, emerging infection lead at UKHSA. “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.”

Robin May, chief scientific adviser at the United Kingdom’s Food Standards Agency added, “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.”

In the United States, the CDC has traced the presence of avian influenza in human cases back to exposure to infected animals through epidemiology studies. However, no person-to-person transmission of the disease has been identified yet, leading to the agency’s low risk assessment to the general public.

The disease has been known to spill over to mammals, such as humans, cows, cats, foxes, seals, dolphins, raccoons and skunks, to name a few.