Recent Outbreaks in Japan

In late October 2025, Japan reported the first highly pathogenic avian influenza (HPAI) outbreak of the season in Hokkaido, after an unusual rise in chicken deaths at a local egg farm. Within days, a second outbreak was confirmed in the same region, followed by a third case in Niigata Prefecture, where over 630,000 laying hens are scheduled to be culled to contain the spread.
Authorities have swiftly implemented quarantine and culling measures to prevent further transmission, underscoring how quickly avian influenza can re-emerge once migratory bird activity increases in autumn.

(Sources: Reuters, Nippon.com)

Understanding the Avian Influenza Virus

Avian Influenza (AI), or bird flu, is caused by the Avian Influenza Virus (AIV) — a type A influenza virus belonging to the Orthomyxoviridae family.
The virus is classified into subtypes based on two surface proteins:

· Hemagglutinin (H) — 18 known types

· Neuraminidase (N) — 11 known types

Common combinations such as H5N1, H7N9, and H9N2 are frequently associated with major outbreaks worldwide.

Depending on pathogenicity, AIV strains are divided into:

· Low Pathogenic Avian Influenza (LPAI) — usually mild but may mutate into more severe forms.

· Highly Pathogenic Avian Influenza (HPAI) — causes severe disease and high mortality in poultry.

The virus spreads through direct contact with infected birds or contaminated environments. Wild migratory birds serve as natural reservoirs, facilitating long-distance transmission between continents.

Seasonal and Geographic Patterns

Avian Influenza follows strong seasonal patterns, typically peaking during autumn and winter in the Northern Hemisphere.
This timing coincides with:

· Migration of wild birds, which increases interspecies contact.

· Cooler temperatures, which allow the virus to survive longer in the environment.

· High-density poultry farming, especially in temperate regions.

Outbreaks often occur between October and March in Asia and Europe — exactly the window in which Japan’s current cases have emerged.

Industry Implications

The recurrence of HPAI cases in Japan highlights an ongoing global challenge for the poultry sector:

· Economic Impact: Large-scale culling disrupts egg and meat supply chains.

· Trade Restrictions: Export bans may be triggered for affected regions.

· Public Health Concerns: Although human infections are rare, some AIV strains have zoonotic potential.

· Surveillance Costs: Continuous testing and genetic monitoring remain essential to control spread.

The Role of Rapid Diagnostics

Early detection remains the cornerstone of Avian Influenza control. Rapid antigen and antibody tests, such as those developed by VETDiagnostix, support:

· On-site screening in poultry farms and live bird markets

· Routine surveillance of high-risk flocks

· Quick decision-making for quarantine and response actions

By combining rapid diagnostics with strict biosecurity, environmental monitoring, and vaccination programs, veterinary authorities and producers can significantly reduce the risk of large-scale outbreaks.

Looking Ahead

As migratory birds continue their seasonal movements and viral reassortment creates new AIV variants, the global poultry industry must remain alert.
Japan’s recent experience serves as a reminder that Avian Influenza remains a recurring and evolving threat — one that requires vigilance, innovation, and cooperation between diagnostic providers, veterinarians, and producers.

VETDiagnostix remains committed to supporting the global effort with reliable, rapid diagnostic solutions — enabling early detection, effective control, and healthier flocks worldwide.

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