H5 Avian influenza: Evolution, spread, and impact
A review article published in Nature Reviews Microbiology provides a comprehensive overview of the emergence, global dissemination, genetic diversification, and cross-species transmission of H5 highly pathogenic avian influenza (HPAI) viruses, particularly those belonging to the A/Goose/Guangdong/1/1996 (Gs/Gd) lineage. The article traces the origins of Gs/Gd H5N1 viruses to 1996 and details their evolution through mutation and reassortment with low pathogenic avian influenza viruses, resulting in the formation of multiple clades and subclades with increasing genetic and antigenic diversity. It documents the intercontinental spread of these viruses via the poultry trade and migratory wild birds, leading to mass mortality events among wild avifauna and, more recently, transmission to mammals, including dairy cattle in the United States. The review also addresses sporadic human infections and underscores phenotypic changes that may indicate enhanced zoonotic or pandemic potential, including instances of mammal-to-mammal transmission and adaptation in mammalian hosts.
This review synthesizes decades of scientific data alongside recent developments to inform policy-making, research priorities, and preparedness strategies aimed at mitigating the persistent and evolving threat posed by H5 avian influenza viruses.
