HPAI season with 17.7 million birds culled
Enforcement Action
In Effect
October 28, 2022
Summary
Between 28 October 2022 and 7 April 2023, Japan experienced its largest recorded highly pathogenic avian influenza (HPAI) season, with 84 confirmed outbreaks at domestic poultry facilities across 26 of Japan’s 47 prefectures. Approximately 17.71 million domestic birds — predominantly commercial layer hens, with some broiler chickens and ducks — were culled under Japan’s stamping-out policy, in which all birds on confirmed outbreak premises are mandatorily depopulated as a disease-control measure. The outbreak season exceeded all previous Japanese HPAI seasons in both case number and culled bird volume; the prior record season (2020–21) had involved approximately 9.87–9.98 million birds culled.
The Ministry of Agriculture, Forestry and Fisheries (MAFF) coordinated outbreak management, issuing culling orders and movement restrictions for confirmed farms and establishing surveillance and restricted zones in surrounding areas. Prefectural governments and local veterinary services carried out on-the-ground culling, carcass disposal, and disinfection operations. Commercial layer farms accounted for 58 of the 84 HPAI cases linked to H5N1. The National Agriculture and Food Research Organization (NARO) / National Institute of Animal Health (NIAH) characterised multiple H5 HPAI virus genetic groups (20E, 21E, and 21RC) circulating simultaneously during the 2022–23 season, linked to lineages from Europe, West Siberia, and China. H5N1 outbreaks were additionally detected in 172 wild bird and environmental samples (September 2022–January 2023), including endangered cranes at the Izumi Plain in Kagoshima Prefecture.
MAFF notified the World Organisation for Animal Health (WOAH) of each outbreak. Following the last recorded poultry outbreak on 7 April 2023 at a farm in Chitose City, Hokkaido, and the required post-outbreak surveillance period, WOAH published Japan’s self-declaration of freedom from avian influenza on 19 June 2023. Economic analyses published in the Journal of Veterinary Medical Science document direct losses of approximately 16.9 billion yen for the national government, 183.5 million yen for prefectures, and 14.2 billion yen for infected poultry farms, excluding disease-control operational costs. Egg supply disruption and domestic price increases were reported nationally during the outbreak period.
Background Context
Japan has experienced recurring HPAI outbreaks since 2004. The 2020–21 and 2021–22 seasons both involved multi-prefecture culling events (approximately 9.87–9.98 million birds and a similar scale respectively), prompting MAFF and prefectural authorities to strengthen surveillance, biosecurity guidance, and diagnostic capacity before the 2022–23 season. NARO-NIAH analysis determined that multiple H5 virus groups detected in 2022–23 were closely related to lineages circulating in Japan in the 2021–22 season, indicating continuity of viral introduction pathways from wild bird migration routes. Japan’s HPAI response framework — mandatory stamping-out on infected premises, movement restrictions in control zones, compensation mechanisms for affected producers — was already codified before the 2022–23 season. Subsequent HPAI seasons in Japan (2023–24 and 2024–25) have involved further culling events in multiple prefectures but at smaller scales than the 2022–23 record.
System Impact
Direction
Reduces Exploitation
Type
Changes Scale
Significance
High
The first confirmed poultry farm outbreak was detected in Okayama and Hokkaido prefectures on 28 October 2022. MAFF coordinated culling operations, movement restrictions, and surveillance zones across 26 prefectures through April 2023. The last confirmed poultry farm outbreak occurred in Chitose City, Hokkaido on 7 April 2023. Simultaneously, H5N1 was detected in 172 wild bird and environmental samples between September 2022 and January 2023. WOAH published Japan’s disease-free declaration on 19 June 2023. Commercial layer farms accounted for 58 of 84 H5N1 cases. NARO-NIAH characterised three concurrent H5 virus genetic groups (20E, 21E, 21RC). Egg price increases were reported nationally during the outbreak period. Peer-reviewed economic analysis (Journal of Veterinary Medical Science) documented aggregate direct losses of approximately 31.3 billion yen across government and farm levels. Subsequent HPAI seasons in Japan have not exceeded the 2022–23 scale.
Anticipated Effects
If MAFF’s updated biosecurity guidance and strengthened surveillance measures from the 2022–23 response are consistently implemented on commercial poultry farms, they would be expected to reduce the risk of farm-level HPAI introduction in subsequent seasons, though recurrent outbreaks in 2023–24 and 2024–25 indicate continued transmission pressure.
Whether the economic losses and production disruption documented in 2022–23 led to structural changes in farm design, stocking practices, or biosecurity investment by commercial poultry operators is not established in available sources.
Significance Rationale
Assigned Reduces Exploitation (impact direction) because approximately 17.7 million poultry were culled and removed from commercial production during the 2022–23 season, constituting a material contraction in the number of birds in commercial poultry production in Japan at that time.
Assigned Changes Scale (impact type) because the primary mechanism is the mandatory mass culling directly reducing the number of birds in poultry production across 84 outbreak premises and 26 prefectures. Biosecurity guidance updates and epidemiological analyses are downstream documentation outputs, not the primary mechanism.
Assigned High significance because the 17.7 million birds culled and 84 farm outbreaks across 26 prefectures are the largest HPAI poultry culling event in Japanese history by documented scale, with egg supply disruption documented nationally and economic losses quantified across government and farm levels at over 31 billion yen. This is approximately double the scale of the previous record HPAI season in Japan.
The scale change is transitional: the poultry system contracted sharply during the 2022–23 season and subsequent seasons have documented partial recovery of production alongside recurrent, smaller-scale HPAI outbreaks.
Key Actors
MAFF coordinated outbreak management and issued culling orders; prefectural governments and local veterinary services executed culling, carcass disposal, and disinfection. NARO-NIAH characterised viral genetics and published technical outbreak summaries. WOAH received outbreak notifications and published Japan’s disease-free declaration on 19 June 2023. Commercial poultry producers on 84 affected farms across 26 prefectures were the directly affected industry actors.
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