Two UK poultry workers have tested positive for bird flu, the UK Health Security Agency (UKHSA) confirmed on Tuesday.
The avian influenza virus was detected following the introduction of an asymptomatic testing programme for humans who have been in contact with infected birds.
The individuals who tested positive have recently worked on an infected poultry farm in England.
However, neither experienced any symptoms of bird flu and both have since tested negative.
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.
Based on the timing of exposures and test results, the UKHSA said one individual is likely to have had contamination of the nose and/or throat from material inhaled on the farm, while for the second individual it is more difficult to determine which is the case.
Further investigation is under way and precautionary contact tracing has been undertaken for this second individual.
The UKHSA says it has not detected evidence of human-to-human bird flu transmission and the two positive cases do not change the level of risk to human health, which remains very low to the general UK population.
“Current evidence suggests that the avian influenza viruses we’re seeing circulating in birds around the world do not spread easily to people.
“However, we know already that the virus can spread to people following close contact with infected birds and this is why, through screening programmes like this one, we are monitoring people who have been exposed to learn more about this risk,” said UKHSA chief medical advisor Professor Susan Hopkins.
She warned that people should still avoid touching sick or dead birds and that they should report any domestic or wild bird with bird flu symptoms.