#16,491
Europe continues to endure another record-setting avian epizootic, caused by the fall arrival of migratory birds carrying the H5Nx (primarily H5N1) clade 2.3.4.4b virus. Yesterday, in UKHSA Statement On Human H5 Infection In England, we saw the UK's first presumed human infection with this virus, although it has jumped to humans previously in Russia and in Nigeria.
In recent months we've seen increased concerns over the zoonotic potential of these H5 avian viruses (see ECDC/EFSA Raise Zoonotic Risk Potential Of Avian H5Nx), although they are of a different lineage (and pose far less danger) than the similarly named Asian H5N1 and H5N6 viruses.
The following DEFRA report, while posted today, was written as of January 4th, and therefore does not include any mention of the human infection reported in the UK yesterday. First a link, and some brief excerpts, from the 24-page report, after which I'll have a brief postscript.
Updated Outbreak Assessment #8
Highly pathogenic avian influenza (HPAI) in the UK,and Europe
04 January 2022 Ref: VITT/1200
HPAI in the UK and Europe Disease Report
Since our last outbreak assessment on 20 December 2021, there continue to be reports of highly pathogenic avian influenza (HPAI) H5 both in Europe and in Great Britain (GB).
There have been a further nine confirmed report cases in GB of HPAI H5N1 in domestic poultry or captive birds since our last assessment, with six in backyard (or captive bird) premises, and three in commercial premises. Northern Ireland have not confirmed any further HPAI H5N1 outbreaks since our last report, therefore the total number of outbreaks in Northern Ireland remains at four.
According to the OIE, high numbers of HPAI H5 reports have continued in Northern Europe over the past two weeks, with spikes in the number of reported cases from France and Germany. Since 20 December, Czech Republic, France, Germany, Hungary, Ireland, Netherlands, Poland, Portugal, Russia, Slovenia and Sweden have reported further outbreaks of HPAI H5N1 in domestic poultry. Bulgaria and Russia have also reported outbreaks of HPAI H5 in domestic poultry.
Wild bird HPAI H5N1 cases continue to be reported in north-west Germany, the Netherlands, Denmark, and Sweden. The Faroe Islands reported HPAI H5N1 in Great Skua from September 2021, however no further cases have been reported. Since our last report, cases of HPAI H5N1 in wild birds have also been reported in Austria, Belgium, Croatia, France, Italy, Poland and Slovenia.
(SNIP)
Conclusion
New cases of HPAI H5 in wild birds and outbreaks in poultry continue to be reported across Europe, including GB, since our last assessment.
Total numbers of migrating wild water birds (ducks, geese, and some swan species) may now be peaking in GB and the majority of wintering water birds have now arrived. There have been multiple confirmed cases of HPAI H5 in wild birds (to 04 January 2022) across a range of species, including resident sedentary species such as raptors and mute swan indicating that they had been exposed to infection in GB. Furthermore, potential bridging species such as gulls and raptors have tested positive. More wild bird HPAI H5 infections are expected including in sedentary GB species and potential bridging species. HPAI H5 will continue to circulate in both susceptible migrant water birds and sedentary bird species within the UK over the next few months, with a greater number of events likely to be observed around water bird wintering sites.
The risk level of HPAI H5 in wild birds is therefore maintained at VERY HIGH across GB. The risk of exposure of poultry across the whole GB is maintained at MEDIUM (with low uncertainty) where good biosecurity is applied, and at HIGH (with low uncertainty) where biosecurity is suboptimal. This assessment takes into consideration the Avian Influenza Protection Zone (AIPZ) and assumes that bird keepers are taking the additional biosecurity measures required.
On 24 November, the Chief Veterinary Officers for England, Scotland, Wales, and Northern Ireland announced housing measures, which came into force on the 29 November 2021. It is now a legal requirement for all bird keepers to keep their birds indoors, to exclude contact with wild birds, and to follow strict biosecurity measures in order to limit the spread of and eradicate the disease. These housing measures build on the strengthened biosecurity requirements that were introduced as part of the AIPZ in GB on 3 November 2021, and in Northern Ireland on 17 November 2021.
We are continuing to closely monitor the situation
We've been watching the evolution of the HPAI H5 avian flu virus since the mid-1990s, after it sparked a small number of cases - and considerable panic - in Hong Kong in 1996. Starting in 2001, it returned with a vengeance (as H5N1) to South East Asia, before spreading globally in 2005.
Since those early beginnings HPAI H5 has reinvented itself - primarily through reassortment - into dozens of clades and subclades. Some - like the Asia lineages of H5N1 and H5N6 - have shown the ability to jump species, with deadly results.
Most, however, have remained only a threat to poultry and wild birds. But the evolutionary process continues, and what was once benign in humans could turn pathogenic overnight. When, or even `if', this ever happens with the current HPAI H5 virus invading Europe is unknown.
Bu we watch them closely, because the more iterations of HPAI that circulate in poultry - or in the wild - the greater the chance that one of them will someday be ready for prime time.
