Highly Pathogenic Avian Influenza: Tracking the Progression from IAV (H5N1) to IAV (H7N9) and Preparing for Emerging Challenges.

Highly Pathogenic Avian Influenza (HPAI) viruses, particularly IAV (H5N1), continue to pose a major global threat due to their widespread circulation and high mortality rates in birds. Management of HPAI is complicated by challenges in conserving migratory bird populations, sustaining poultry production, and uncertainties in disease dynamics. Structured decision-making frameworks, such as those based on the PrOACT model, are recommended to improve outbreak response and guide critical actions, especially when HPAI virus (HPAIV) detections occur in sensitive areas like wildlife refuges. Surveillance data from late 2024 to early 2025 show persistent HPAI activity, with 743 detections across 22 European countries and beyond, and notable outbreaks in poultry in nations like Hungary, Iceland, and the UK. The proximity of poultry farms to water sources increases environmental contamination risks. Meanwhile, HPAI A(IAV (H5N1)) and other H5Nx viruses have been detected in a wide range of mammalian species globally, raising concerns about mammalian adaptation due to mutations like E627K and D701N in the PB2 protein. Human infections with IAV (H5N1) have also been reported, with recent cases in North America highlighting zoonotic transmission risks. Molecular studies emphasize the importance of monitoring genetic variations associated with increased virulence and antiviral resistance. Preventive strategies focus on biosafety, personal protective measures, and vaccine development for both avian and human populations. Ongoing genetic characterization and vigilant surveillance remain critical to managing the evolving threat posed by HPAI viruses.