Two poultry workers have tested positive for bird flu in the United Kingdom after coming into contact with infected birds.
The United Kingdom's Health Security Agency (UKHSA) confirmed the two cases recently worked on an infected poultry farm in England, but neither person had any symptoms.
A screening programme for asymptomatic poultry farm workers that have contact with infected birds picked up the pair of cases - but they've since tested negative.
UKHSA's chief medical advisor Professor Susan Hopkins said evidence suggests avian viruses like bird influenza don't easily spread to people.
"However, we know already that the virus can spread to people following close contact with infected birds."
She argues screening programmes are essential because viruses can mutate.
"We know that viruses evolve all the time and we remain vigilant for any evidence of changing risk to the population."
Humans can test positive for avian influenza (bird flu) viruses even if it's just the nose and throat contaminated by breathing in material on infected farms.
One of the workers was likely to not have a true infection, only bodily contamination, based on exposure times and test results, whereas it's less clear for the other worker - for whom contract tracing has begun.
The UKHSA said it has no evidence of community transmission yet, adding the risk to the public remains very low.
It advises people to avoid touching sick or dead birds.
It comes after Reuters and other news agencies revealed in February that bird flu has become endemic for the first time in some wild birds that can pass the virus on to poultry, and infectious disease experts now warn it's a year-round problem.
