Major Global Migratory Flyways – Credit FAO
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Last year saw the emergence of several unique North American H5N1 genotypes (B3.13 in the spring, and D.1, D.2, and D.3 in the fall) - which in addition to infecting millions of wild birds and poultry - have gone on to infect hundreds of dairy herds (B3.13 and D.1) caused at least one spillover into pigs (D.2), and have infected hundreds of other mammals in the United States.
Both B3.13 and D.1/D.x genotypes have also infected humans (n=70), with B3.13 infections tending to be minor, while D.1 has produced several severe illnesses and one fatality.
Until now, this has been viewed by the rest of the world as a `North American' problem - as so far - these aggressive genotypes have been limited to the United States and Canada.
But the global dynamics of avian flu often shift following the summer roosting season, where hundreds of millions of migratory birds spend a few months in Alaska, Siberia, Northern Canada and the Arctic before returning in the fall.
There, they often share viruses, which sometimes generate new genotypes or subtypes (see Sci Repts.: Southward Autumn Migration Of Waterfowl Facilitates Transmission Of HPAI H5N1).
This annual avian `mass gathering event' is an ideal way for these North American viruses to be spread to birds that may head to Asia or Europe this fall. Which means that what happens in North America doesn't necessarily stay in North America.
While there are no guarantees that B3.13 or D1.x will spread globally - or even return to North America this fall - the world must be ready for surprises (see H5Nx: Reassort & Repeat).
South Korea has been aggressively preparing for the avian flu threat over the past year, releasing a new pandemic plan last summer, and 3 weeks ago announcing a a 19-day, Nationwide, Mock-Training Exercise to Prepare for Zoonotic Influenza.
Today South Korea's MAFRA (Ministry of Agriculture, Food and Rural Affairs) released the following press release on a major exercise to prepare for a spillover of avian influenza into livestock.
First today's announcement, after which I'll have a bit more.
(translated)
2025.09.22 16:00:00 Foot-and-Mouth Disease Prevention Division, Quarantine Policy Bureau
The Ministry of Agriculture, Food and Rural Affairs ( Minister Song Mee-ryeong , hereinafter referred to as the Ministry of Agriculture, Food and Rural Affairs ) conducted the “ 2025 Mammalian Avian Influenza Disaster Response Virtual Quarantine Training” on September 22 in Yeongyang-gun, Gyeongsangbuk-do.The training was jointly hosted by the Ministry of Agriculture, Food and Rural Affairs, Gyeongsangbuk-do Province, and Yeongyang-gun, and was attended by about 100 people from related organizations such as the Ministry of Environment , the Korea Disease Control and Prevention Agency , the Animal and Plant Quarantine Agency, the Livestock Quarantine Support Center , and the National Agricultural Cooperative Federation .
This training was conducted as a virtual quarantine training with the possibility of the virus entering domestic dairy farms in mind, as the damage has spread since the first outbreak of highly pathogenic avian influenza in dairy cows in Texas, USA in March 2024 , with outbreaks occurring in 973 farms across 17 states .
The Ministry of Agriculture, Food and Rural Affairs preemptively inspected the crisis management response capabilities and inter-agency cooperation systems of each institution according to the Emergency Action Guidelines (SOP) at each stage* during the process of rapid situation assessment (confirmation of occurrence/damage) and quarantine measures ( response measures and recovery/restoration) in the event of an outbreak, focusing on the revised 「Emergency Action Guidelines ( SOP ) for Mammalian Avian Influenza 」this year .
( Step 1 ) Detection of highly pathogenic AI in wild cats
( Step 2 ) Occurrence of suspected AI in dairy cattle
( Step 3 ) Confirmation of highly pathogenic AI in dairy cattle
The Ministry of Agriculture, Food and Rural Affairs expects that this virtual training will strengthen the mammalian avian influenza response capabilities of all participating organizations , and plans to immediately improve any shortcomings discovered during this training .
Choi Jeong-rok, Director of the Quarantine Policy Bureau at the Ministry of Agriculture , Food and Rural Affairs, who hosted this training , said , “ This virtual quarantine training for mammalian avian influenza disaster response was the first training conducted since the establishment of the Standard Operating Procedure (SOP) , but it was a good opportunity to once again check the roles of related organizations, local governments, and participating organizations . ”He added , “ I expect that each organization’s quarantine awareness and initial response capabilities will improve, and we will continue to continuously review our response system for disasters according to the situation that reflects the outbreak patterns of mammalian avian influenza . ”
Attached is the 2025 Mammalian Avian Influenza Disaster Response Virtual Quarantine Training Plan.
As recently as 8 months ago, the only H5N1 genotype thought likely to infect cattle was B3.13. But last February, we saw dairy herds in two different states infected with genotype D.1.
Since then both the UK and Norway have reported H5N1 infections in sheep from European strains of the virus (see EM&I: Detection of Clade 2.3.4.4b H5N1 High Pathogenicity Avian Influenza Virus in a Sheep in Great Britain, 2025), and last year we saw serological evidence of HPAI H5 virus exposure in goats and sheep from Pakistan.
All of which makes exercises like today's in South Korea not only prudent, but essential, since we can't depend upon HPAI H5Nx to always act tomorrow the way it has acted in the past.
