24.07.2025

A study published in Scientific Reports analyzed 69 infected (case) farms and 361 nearby uninfected (control) farms, focusing on layer and broiler production types. The study exclusively examined two main production systems: layer farms, which raise egg-laying chickens, and broiler farms. Other types of poultry and avian farms were excluded from the analysis.
Japan experienced a notable surge in highly pathogenic avian influenza (HPAI) cases during the 2022–2023 season, affecting numerous farms across various poultry production systems. The study aimed to investigate the interconnected risk factors associated with HPAI outbreaks on Japanese chicken farms during this period.
The analysis revealed that certain farm characteristics significantly influenced the risk of HPAI infection. Notably, layer farms and farms with larger flock sizes exhibited a higher probability of infection. In addition, proximity to water bodies, natural reservoirs of influenza viruses, was identified as a significant environmental risk factor.