Infectious Diseases 2025

Infectious Diseases 2025

USA: First outbreak of H5N9 avian influenza in poultry

27 January, 2025

The United States has confirmed its first outbreak of H5N9 (Eurasian lineage goose/Guangdong clade 2.3.4.4b) avian influenza in poultry, specifically on a duck farm located in California. U.S. authorities also identified the more prevalent H5N1 strain at the same farm in Merced County, California. According to the report submitted to WOAH, nearly 119,000 birds on the farm were culled by December 2. This incident marks the first verified occurrence of Highly Pathogenic Avian Influenza (HPAI) H5N9 in poultry within the United States.