Highly pathogenic avian influenza H5N1 in the United States: recent incursions and spillover to cattle

Nature Since Spring 2024, new genotypes of highly pathogenic avian influenza (HPAI) H5N1 clade 2.3.4.4b have been identified in the United States (US). These HPAI H5N1 genotypes have caused unprecedented multi-state outbreaks in poultry and dairy farms, and human infections. Here, we discuss the current situation of this outbreak and emphasizes the need for pre-pandemic preparedness to control HPAI H5N1 in both poultry and dairy farms in the US. The highly Pathogenic Avian Influenza H5N1 (HPAI H5N1) was first detected in chickens in Scottland in 1959 and has since circulated globally¹. In 1996, the HPAI H5N1 virus was reported in domestic waterfowl in Southern China, known as A/Goose/Guangdong/1/1996 or Gs/Gd lineage, resulting in the first known human infections, responsible of 18 human cases, including 6 deaths in 1997 in Hong Kong². For almost 30 years, the virus spread via migratory birds in waves to the terrestrial avian hosts and mammalian species throughout the world leading to significant diversities in evolutionary virus lineages and clades².