THE number of avian influenza outbreaks and wild bird’ events’ was broadly the same in January this year as the month before, December 2022.
Between 6 December and 4 January, there were nine outbreaks in commercial poultry flocks in Great Britain and four in non-commercial premises.
This compares with nine outbreaks in commercial flocks and 6 in non-commercial premises a month earlier.
In both periods, 74 HPAI H5 events were detected in wild birds, according to Defra’s two most recent avian influenza outbreak assessments.
The latest, which covers the four weeks to 6 February, says the risk levels remain unchanged – very high for wild birds, medium for poultry farms with stringent biosecurity and high for farms with suboptimal biosecurity.
Four of the nine commercial outbreaks were in Norfolk, with single outbreaks in Aberdeenshire, the Highland Council region and in Cumbria, Dumfries and Galloway and Fife.
It is markedly different to October last year when between 15-26 outbreaks were identified every week.
Defra said the decline in IPs could reflect the introduction of housing orders across UK nations and the depletion of seasonal turkeys before Christmas.
But it adds that, with outbreaks still occurring, “from a risk assessment perspective, the current risk levels to poultry cannot be reduced while the wild bird risk is still at very high”.
Arrivals of migratory wild waterfowl that overwinter in Great Britain peaked in December and January, with most staying until early April when they depart for breeding grounds in northern Europe.
That departure in other years has presented a heightened risk. But this year, given the presence of AI in the UK, the impact of that migration should have been felt already, Defra said.
Wild bird dispersal
“This raises the question of how much their departure in early April will contribute to reducing the risk to poultry.
“Of greater importance in reducing prevalence in wild birds may be the general dispersion of wild birds from areas that they gather, particularly at wetland sites, in early spring as the resident wild birds move to their remote breeding sites across the country.
“At their breeding sites, bird-to-bird contacts will be greatly reduced for most species compared to at the winter gathering sites.
“Most resident GB waterbird species that breed in the UK do not breed together in large numbers, the exception being seabirds around the coast that will start to return to their breeding colonies from February/March.
“The increase in day length and ambient temperatures in the coming weeks will reduce survival of the HPAI H5N1 virus in the environment although circulation of virus in waterbirds may be maintained until their spring dispersal in early April.
“It remains to be seen what effect the gathering of seabirds to breeding colonies has on virus transmission in those species.”
Defra concludes by reinforcing biosecurity – both in the day-to-day management of farms and their maintenance – remains critical to minimising the risk of an outbreak.
The full outbreak assessment and more information can be found on Defra’s website.