In 2020, the highly pathogenic avian influenza (HPAI) virus subtype H5N1 clade 2.3.4.4b caused an unprecedented number of deaths among wild birds and poultry in numerous countries in Africa, Asia, and Europe. In 2021 this virus spread through the main migratory routes of waterfowl to North America and, in 2022, to Central and South America. By 2023, outbreaks in animals had been reported by 14 countries and territories, mainly in the Americas.