The UK Health Security Agency said on Tuesday that it has detected influenza A (H5) virus in two people.
The virus has been detected in two poultry workers, following the introduction of an asymptomatic testing program for people who have been in contact with infected birds, the agency said in a statement.
The two are known to have recently worked on an infected poultry farm in England, the statement said, adding that none of them has experienced any symptoms of avian influenza.
"Detection of avian influenza in poultry workers can follow contamination of the nose and throat from breathing in material on the affected farm or can be true infection. It can be difficult to distinguish these in people who have no symptoms," it added.
In the statement, Susan Hopkins, chief medical advisor at the agency, recalled that the virus can spread to people following close contact with infected birds.
"Globally there is no evidence of spread of this strain from person to person, but we know that viruses evolve all the time and we remain vigilant for any evidence of changing risk to the population," she said.
Hopkins also advised people to refrain from touching sick or dead birds.
