HPAI H5 Outbreaks July 25th-30th
#18,817
Typically summer is a slow time for avian flu, particularly in temperate zones. Over the past week, however, the UK has reported no fewer than 4 new HPAI H5 outbreaks in poultry, scattered across their Kingdom.
This is a significant uptick, since in 2024 the UK went from February to November without reporting a single H5 outbreak. Previously, between May 12th and June 22nd 2025, the UK reported 6 infected premises.
After a lull of just over a month, over the past 6 days the UK's Defra has reported:
Bird flu: near Attleborough, Breckland, Norfolk (AIV 2025/53)
type: Bird flu (avian influenza) Control zone restriction: In force
Control zone type: Protection zone and 1 others
Virus strain: H5N1
Opened: 30 July 2025
Bird flu: near Tiverton, Mid Devon, Devon (AIV 2025/52)type: Bird flu (avian influenza)Control zone restriction: In forceControl zone type: Protection zone and 1 othersVirus strain: H5N1Opened: 30 July 2025
type: Bird flu (avian influenza)Control zone restriction: In forceControl zone type: Protection zone and 1 othersVirus strain: H5N1Opened: 28 July 2025
type: Bird flu (avian influenza)Control zone restriction: In forceControl zone type: Captive bird (monitoring) controlled zoneVirus strain: H5N1Opened: 25 July 2025
Cases are well scattered across the Kingdom, and all are reported as HPAI H5N1.
From Defra's most recent (July 21st) High pathogenicity avian influenza (HPAI) in Great Britain and Europe, we see the following outbreak map showing increased activity in May-June-July in and around the UK.
Map 3. HPAI events in domestic poultry and wild birds in Europe reported by WOAH between 12 May and 21 July 2025 (WOAH, 2025). Wild bird cases and poultry outbreaks are concentrated in Great Britain, Ireland and across the English Channel but only sporadic across eastern and central Europe with some cases in Spain and Portugal, as described in the main body of this report above.
This report was issued prior to the 4 most recent IPs (Infected premises), and after having gone 4 weeks (June 22nd-July 21st) without any outbreaks in poultry.
In years past, that has suggested the expected summer lull in bird flu outbreaks had arrived.
In the report's conclusion, the authors wrote:
Since our last assessment on 12 May 2025 (HPAI in Great Britain and Europe May 2025),cases of HPAI H5Nx have continued in gulls and seabirds through June and into July.Therefore, the national risk level for HPAI H5 in wild birds is maintained at HIGH (occurs very often). Most of the wild bird cases in the last month have been coastal and not inland.
There have been no IPs in Great Britain for the last 4 weeks, with low numbers reported in the weeks preceding that. This suggests that the risk between infection in poultry and detection in wild birds is becoming decoupled as has been seen in previous years when HPAI H5 has over-summered in seabirds and gulls around the coast.The risk of infection of poultry in Great Britain with suboptimal biosecurity is therefore lowered to LOW (rare but does occur) with high uncertainty. The risk to poultry with stringent biosecurity is maintained at LOW (rare but does occur) with low uncertainty
A reasonable assessment given the patterns we've seen in recent years, and the relative drought of outbreaks reported on the Continent. But as we've repeatedly seen, HPAI often throws curve balls.
Whether this summer uptick is an aberration or a trend, is something we'll simply have to wait to see.
But this is a reminder that our powers of prognostication when it comes to what avian flu will - or won't - do, remain quite limited.
