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Irish scientists comment on a suspected case of Avian flu detected in Northern Ireland.
Professor Ian Brown, Group Leader at the Pirbright Institute, said;
“This new case in NI is not unexpected and follows many cases in GB. The current risk level across the UK is very high for wild birds which means commercial poultry flocks are at elevated risk right now for spread of virus. Rapid culling, premises disinfection, restrictions on movements in the immediate area is a proven method for limiting spread. Application of biosecurity measures on farms is the best defence against the virus but recognising this can be challenging and probably negatively exacerbated by excessive rainfall. Previous cases in NI over several years have involved various size flocks. Swift control in birds helps reduce human exposure risk but currently these European viruses present very low risk to public health. NI introduced a mandatory housing order for all birds on 17/2/25, a measure designed to better protect birds from exposure and linked to current high levels of risk in wild birds.”
Paul Wigley, Professor of Animal Microbial Ecosystems, University of Bristol, said;
“Outbreaks of avian influenza tend to occur in winter months due to migratory birds bringing the virus from Russia and central Asia where the breeding grounds are. Whilst outbreaks occur most winters in recent years these have been larger and with particularly virulent H5N1 strains. Northen Ireland is a concentrated area for chicken production so outbreaks of any infectious disease can have a large impact. Surveillance for influenza is strong throughout the UK and well supported by both independent farmers and large production companies. The high levels of biosecurity in the industry help reduce the transmission of influenza, but outbreaks still occur. Currently biosecurity including housing all birds indoors and movement restrictions are the main tool to reduce transmission. Unfortunately removing infected birds by culling is needed to remove major reservoirs of infection. Given the high virulence of what we call High Pathogenicity Avian Influenza (HPAI) like H5N1 it’s likely many, if not all, birds on an infected premise would become severely ill and die, so there is some welfare benefit in culling. There is no treatment for HPAI and currently vaccination is not permitted and whilst this would lower risk to individual farms it has a downside in reducing both the capacity to export meat or eggs nationally and could potentially lead to more virulent strains emerging in certain circumstances.
“Currently there is no direct risk to the public other than through close contact with infected birds. The advice from DAERA in Northern Ireland and DEFRA on mainland UK remains to avoid direct contact with potentially infected birds and to report any suspected cases such as dead wild birds. There does remain a very low risk that H5N1 can ‘jump species’ to mammals or even humans. This is currently closely monitored with no evidence of transmission between humans, and any cases being in those with close contact with poultry.”
Dr Connor Bamford, virologist, Queen’s University Belfast – Institute for Global Food Security & School of Biological Sciences, and also a leading member of the Northern Ireland Avian Influenza Forum, NIAIF, said:
Is this unusual or pretty standard?
“The humane culling of large numbers of co-housed poultry (chickens) in response to detection of highly pathogenic avian influenza (HPAI) in the flock/premises is a routine measure to control the spread of HPAI viruses, and to maintain high standards of animal welfare.”
Is the number of birds being culled now bigger than when we’ve had avian flu in Ireland before?
“Similar numbers have been reported to be culled before in NI (e.g. https://news.sky.com/story/bird-flu-uks-largest-ever-outbreak-of-avian-influenza-reported-in-northern-ireland-12493841 in 2021 ). The numbers culled is less a reflection on the virus and more on the degree of poultry density at the premises. Even if a few HPAI positive cases were noted the entire population would be culled because of how fast and how lethal this virus can be to chickens.”
Is this normal biosecurity when cases are detected?
“Yes (See above). This in collaboration with other biosecurity methods on limiting virus spread within and between poultry premises and wildlife, such as extensive cleaning and maintenance of physical barriers. Currently, vaccination of chickens against HPAI in the UK and Ireland is not recommended.”
Do we know why cases have been detected recently — is it just the same as what is happening elsewhere in the world too?
“HPAI is taken very seriously and in the UK, we are currently in the midst of our HPAI season during winter that also sees the migration of wild birds to the British Isles. As such, we are on heightened alert of HPAI cases. If wild or domestic animals are thought to have HPAI then testing is rapidly deployed locally and nationally to confirm HPAI virus presence. Similar processes occur across the UK, Europe and the world.”
Is it sensible that these birds are being culled, and why?
“Humane culling is based on two reasons: 1) prevention of onward spread of the virus within a premises, between poultry premises, and between them and wildlife that remain susceptible, including wild birds and mammals including people and cows; and 2) animal welfare concerns, whereby HPAI is such a terrible disease (organ damage throughout the chicken’s body, including neurological symptoms that lead to death), and that it spreads so rapidly to many chickens, sometimes on the order of hours.”
Is there any reason the public in Ireland should be worried about risk to human health from these outbreaks?
“HPAI is typically not a major issue for the general public yet. But human infections can occur, and they can cause severe disease. With influenza, there remains a real risk of large outbreaks or even pandemics occurring from animal influenza viruses jumping into people. This is one of the reasons we take avian influenza so seriously.”
What can and should farmers be doing to limit the spread of avian flu?
“Those in the poultry industry or those farming chickens in the backyard (or ducks and other fowl), are well accustomed to preventing avian influenza through robust biosecurity measures and vigilance of their animal’s health. If suspected HPAI, alert the authorities rapidly to allow testing, and take care when around potentially-HPAI infected animals. Other farmers must also be aware that current strains of HPAI may be able to infect cattle, particularly via milking.
One additional point is to ask, what else should the country/region be doing to limit the impact of avian influenza? Is our surveillance and tracking of the virus up-to-scratch? Are we utilising the best protective measures, like targeted animal/human vaccination? How do we ensure harmonious collaboration between those interested in protecting the health of livestock, humans, and wildlife?”
https://www.rte.ie/news/ulster/2025/0223/1498425-bird-flu-northern-ireland/
https://www.bbc.co.uk/news/articles/c5ym48gmm05o
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