Avian flu risk to poultry raised in Great Britain

Over the past two weeks, Great Britain is the only European country to have confirmed new outbreaks of highly pathogenic avian influenza affecting commercial poultry flocks.

Since the last days of July, six outbreaks of HPAI affecting farmed poultry in the United Kingdom have been reported by the government agriculture department, Defra. Following a partial hiatus in the months of April and May, these bring the nation’s total outbreaks to date this year to 59.

In each case, the presence of the H5N1 HPAI virus serotype has been confirmed.

As a consequence of these developments and the slow but ongoing discovery of infections in wild birds widely across the country, Defra has raised the HPAI risk level to “medium” for poultry kept in conditions of sub-optimal biosecurity. For poultry flocks with high biosecurity, the risk remains assessed as “low,” but is now assigned a “medium” level of uncertainty.

In Great Britain, an Avian Influenza Prevention Zone (AIPZ) has been in effect since January 25, 2025. As well as implementing enhanced biosecurity measures to limit spread of the disease, regional housing orders have been enforced in affected areas, requiring poultry to be kept indoors.

Among the latest flocks to have tested positive for HPAI have been one each of turkeys and broiler chickens in the eastern English county of Norfolk, and one farm with ducks in Devon in the south-west. Two other outbreaks in Devon involved pheasants — either as the only species or farmed alongside ducks.

Affected at the sixth premises were around 88,000 laying hens in Aberdeenshire in eastern Scotland, according to the official notification from the national animal health authority to the World Organisation for Animal Health (WOAH).

HPAI situation in Europe’s poultry flocks
Over the past two weeks, Great Britain is the only state in the region to have confirmed HPAI on farms.

So far this year, 19 countries in the region have together reported a total of 252 HPAI outbreaks affecting commercial poultry flocks, according the Animal Disease Information System (as of August 13). Administered by the European Commission (EC), the database monitors listed animal diseases in European Union member states and selected adjacent countries. These include Türkiye (Turkey), but not Great Britain.

With 105 outbreaks, Hungary remains the country recording the most outbreaks in farmed poultry to date in 2025, followed by Poland (85).

During the whole of last year, 451 outbreaks in this population were registered by 20 countries with the EC System.

Non-commercial birds hit by HPAI in 4 countries
The EC's database has a separate category to monitor HPAI outbreaks affecting captive birds, which covers backyard/hobby poultry and zoos.

As of August 13, 18 countries had registered a total of 75 outbreaks in this population. These include the first entries in this category for the Republic of Ireland and Spain, as well as a further outbreak in Portugal.

Further detail on these developments is provided by official notifications from the national veterinary agencies to WOAH.

Starting in mid-July, the Spanish outbreak involved 132 birds in the Basque Country, while a small flock of backyard poultry in County Donegal tested positive for the H5N1 virus towards the end of the same month.

Around the same time, Portugal’s fourth outbreak in this category in 2025 occurred in a non-commercial poultry flock in the Setubal district.

Two recent outbreaks in non-commercial birds in Great Britain involved a backyard poultry flock in County Durham in northeast England, ad another comprising falcons for pest control in the southwestern county of Somerset.

For comparison, 17 countries registered a total of 142 outbreaks in captive birds through the EC’s System in 2024. 

New avian flu infections in wild populations
Since the start of August, seven European states have logged new cases of HPAI in wild birds with the EC.

Six additional outbreaks linked to the H5N1 virus variant were confirmed by each of France and Spain, four by Belgium, and one by each of Hungary and the Republic of Ireland.

Meanwhile, Norway confirmed three further outbreaks linked to the H5N5 serotype.

As of August 13, a total of 631 outbreaks in wild birds (covering all virus serotypes) had been registered with the EC System by 31 states so far this year.

During the whole of 2024, 32 countries logged a total of 926 HPAI outbreaks in wild birds with the database.

Over the past two weeks, WOAH was notified by the authority in Great Britain that a further 53 wild birds had tested positive for the H5N1 virus.

In May of this year, a wild seal found dead on the coast in southwest England tested positive for a low-pathogenic H7N1 avian flu virus. According to Defra, source of the infection was likely to be wild birds. A mammalian adaptation of the virus involved one gene, and had been observed in previous cases. It is uncertain if the infection was the cause of death in this case.

Source: WattAgNet.