Avian Influenza Prevention Zone: declaration January 2025

Veterinary Risk Assessment regarding the introduction in Scotland of an Avian Influenza Prevention Zone (AIPZ) in January 2025

Background

There are ongoing Highly Pathogenic Avian Influenza (HPAI) serotypes H5N1 and H5N5 outbreaks across GB. Detailed information can be consulted on the Avian influenza outbreaks page.

Under article 6 of The Avian Influenza and Influenza of Avian Origin in Mammals (Scotland) Order 2006, Scottish Ministers may consider the introduction of an AIPZ in Scotland to reduce the risk of the transmission of avian influenza to poultry or other captive birds in Scotland from wild birds or from any other source.

This risk assessment compares the background level of risk in Scotland to poultry with the mitigating effects of implementing an AIPZ in its current form and can be used to inform such a decision.

The risk question

Is the imposition of an AIPZ in Scotland necessary to reduce the risk of HPAI transmission to poultry or other kept birds from wild birds?

Hazard

The hazard in this risk assessment is Highly Pathogenic Avian Influenza (HPAI) virus, serotype H5N1 in particular (although H5N5 has also been detected this season and contributes to the overall risk).

Risk factors

The risk levels of HPAI in GB is assessed weekly by experts from the Animal and Plant Health Agency (APHA) and agreed with Chief Veterinary Officers.

As of 24 January 2025, the risk is of HPAI in Wild Birds (WBs) remains very high where it has been since December. The risk to poultry is high (except in premises with stringent biosecurity, where it is medium).

There have been 22 cases of HPAI H5N1 in kept birds in GB this season (21 in England, 1 in Scotland), with 5 new cases confirmed in the past 7 days. Cases were initially clustered in the East of England however have since spread to the Midlands and North Yorkshire.

There have been 12 confirmed cases of HPAI H5N1 in wild birds in Scotland since 1 January 2025, 7 of which in pink-footed geese (PFG).

Mitigating factors

The current measures in the AIPZ declaration can be consulted at AIPZ all Scotland declaration and address the various types of risk transmission pathways of HPAI from wild birds.

Discussion

The central argument in this assessment is that the background risk to poultry in Scotland has been rising and the imposition of an AIPZ will help reduce it and potentially prevent cases in poultry.

If the AIPZ is introduced, there will be likely fewer poultry premises in Scotland with suboptimal biosecurity (and therefore at high risk from infection in WBs) than otherwise. Premises with stringent biosecurity are at medium risk.

Risk

It is recognised that risk across GB is not homogenous. Detection of HPAI so far this season occurred overwhelmingly in England, however we have reasons to believe that the risk is rising in Scotland.  This is because the risk transmission pathways that extend risk geographically into Scotland are plausible, namely the domestic migration of certain bird species.

Pink-footed geese (PFG) are considered to play a particularly important role in the wild bird epidemiology and spread of HPAI across GB owing to their high numbers, distribution and frequency of movements, presence in wetland habitats with a high degree of mixing, as well as being a “non-indicator” species.

This role of PFG in the epidemiology is additionally relevant at this moment in time as they commence northerly migrations, which is likely to increase the risk across Scotland over the next few weeks. Therefore, the imposition of an AIPZ now may help mitigate that risk.

Other bird species also contribute to the epidemiology of HPAI.

Risk pathways

The vast majority of poultry and other captive birds HPAI cases in GB over the last few years (and probably ever) can be attributed to direct or indirect exposure to infection in wild birds.

This is clear in the epidemiology reports which are produced by APHA for every single case in kept birds. The risk pathways for these infections are invariably those which can be mitigated through biosecurity, from direct contact with wild birds or their excretions outdoors or indoors where access and contamination is possible, or indirect contact through equipment including feeders and drinkers, workwear, water runoff, flooding, and many others.

Role of AIPZ

An AIPZ creates a legal obligation upon bird keepers to implement biosecurity measures on their premises to protect their birds. These include many actions which constitute good practice against many other diseases irrespective of the risk of HPAI, and many keepers already implement them in particular at commercial units. However, it is well known from field investigations that adherence to stringent biosecurity varies between premises and even in time within the same premises.

Therefore, the raised awareness amongst keepers and the enforceability of such measures in an AIPZ is likely to improve overall biosecurity, modify behaviours and ultimately increase the number of poultry premises where keepers implement stringent biosecurity, and whose risk decreases from high to medium.

Conclusion

Implementing an AIPZ in Scotland is likely to mitigate the risks to poultry and other kept birds, in the face of a rising background risk in WBs. This measure should be done now to pre-empt an expected rise in WB risk owing to the migration of pink-footed geese in particular.

The risk in kept and wild birds is continuously monitored and this VRA should be reviewed and updated in light of changes in risk.

References

• Latest HPAI situation
• AIPZ declaration with schedule of conditions
• APHA NEEG advice regarding wild birds in Scotland – draft seen 24/01/2025
• APHA NEEG advice to CVOs regarding risk levels across GB – email 23/01/2025