Since December 2021, 10 human cases of H5N1 avian influenza (clade 220.127.116.11b) have been reported worldwide and between October 1, 2022 and May 31, 2023, H5N1 influenza has been confirmed in birds in 185 stores in the UK.
During the same period, H5N1 was also detected in 1,024 wild birds across the UK.
Our surveillance and diagnostic expertise, along with our genomic sequencing capabilities, are crucial for early detection, assessment, and response to emerging health and biosecurity threats, such as avian influenza.
Through these surveillance systems, we aim to detect possible cases of avian influenza in humans early, assess the risk to human health, and scale up the public health response at an accelerated pace.
Our work also contributes to initiatives such as WHO’s Global Influenza Surveillance and Response System, which helps the world detect and respond to emerging influenza viruses with pandemic potential.
Enhanced Surveillance Program
In the UK and around the world, levels of avian influenza infections in birds and mammals have increased; however, very few human cases of H5N1 (18.104.22.168b) avian influenza virus have been reported internationally, making it difficult to assess the severity of the threat. It is for human health. To support a better scientific understanding of the threat, in March 2023 the UKHSA launched a new surveillance program for asymptomatic avian influenza.
This program aims to detect potential animal-to-human infections in people who are exposed to infected birds, for example, poultry workers and those involved in the slaughter of infected domestic and commercial premises, so that we can better understand if transmissions are occurring. from birds to humans and if so, how often. This information will allow us to better understand the overall risk to human health and tailor our public health response.
Samples are taken from people participating in the program through virological swabs from the nose and throat. Samples are then processed by UKHSA testing laboratories, and any positive samples are sent to the WHO designated National Influenza Reference Laboratory at our Colindale laboratory for genomic analysis.
If a positive test is returned, people will be managed in accordance with current UKHSA guidance. As part of the public health response to any positive detection, our health protection teams follow up on everyone who has been in contact with a confirmed human case of avian influenza.
The asymptomatic avian influenza surveillance program has already successfully identified positive tests for potential cases in two people working on an infected poultry farm in England. This scheme builds on a previous asymptomatic testing program that took place in the winter of 2021/22, included around 120 samples and identified one positive case with a history of unprotected contact with birds in a close domestic environment.
In conjunction with this surveillance program for asymptomatic avian influenza, we are working with the NHS to ensure that patients admitted to intensive care with severe acute respiratory infections or influenza-like illnesses are screened for respiratory viruses, including influenza. UKHSA Public Health Laboratories and the Influenza Reference Laboratory carry out additional testing of samples that test positive for influenza A but where normal seasonal influenza is not found, to confirm that the detection is not due to avian influenza.
Tracking these samples is an important mechanism for the early detection of avian influenza/novel influenza viruses. Since people who develop avian influenza infections are likely to be seriously ill, intensive care units are a good place to focus disease surveillance; this work fits within broader surveillance programs alongside the existing contact management process, where people who are exposed to birds with avian influenza are monitored by UKHSA health protection teams.
The latest evidence continues to suggest that the avian influenza virus we are seeing circulating in birds currently does not spread easily to people.
Defra’s guidance on the signs of avian influenza and how to report it in poultry and other birds is available on GOV.UK, while the Health and Safety Executive publishes further guidance on avoiding the risk of infection when working with infected birds.