Two poultry workers have tested positive for bird flu after coming into contact with infected birds on the same farm in England, according to the UK Health Security Agency.
The cases were picked up through a screening programme for people who have come into close contact with the virus, though neither individual suffered symptoms and both have since tested negative.
Health officials said there were no signs of person-to-person transmission of the virus, which has spread dramatically in wild bird populations and affected other species, but added that contact tracing was being carried out for one of the workers as a precaution.
“Current evidence suggests that the avian influenza viruses we’re seeing circulating in birds around the world do not spread easily to people,” said Prof Susan Hopkins, the chief medical adviser at UKHSA. “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.”
Based on the timing of the poultry workers’ exposure and their test results, the UKHSA said it believed one of the cases was not infected with avian flu, but had inhaled virus-containing material into their nose and throat that triggered a positive result on a nasal swab.
In the second case, health officials have not ruled out an infection with the virus, though, as with the first case, the person may have inhaled virus that did not establish itself as an infection. The UKHSA said that person was the focus of an ongoing investigation and that precautionary contact tracing was undertaken. Both cases are thought to relate to the H5N1 strain of avian flu.
The two cases are the latest since January 2022 when a person living in the south-west of England was found to be infected with avian influenza. The UKHSA found no evidence of onward transmission from the infected individual. The agency said the two new cases did not change the level of risk to human health, which remains “very low” for the general population.
“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,” said Hopkins. “It remains critical that people avoid touching sick or dead birds, and that they follow the Defra advice about reporting.”
Health protection teams at the UKHSA make daily contact with individuals who are at high risk of exposure to avian flu to ask about any symptoms they may be experiencing. The latest two cases were detected through the agency’s asymptomatic surveillance programme, where poultry workers are asked to take nose and throat swabs which are tested for the virus for 10 days after exposure.
Some workers are also asked to provide finger prick blood tests which the UKHSA checks for antibodies against avian influenza, which would point to an infection that has triggered the body’s immune defences.
• This article was amended on 17 May 2023 to clarify that both cases are thought to relate to the H5N1 strain of avian flu. An earlier version indicated that this had been confirmed.
