Under new rules, poultry facilities seeking indemnity payments after repeated bird flu infections must show biosecurity precautions

H5N9 is a rare subtype of the influenza A virus that can cause highly pathogenic avian influenza (HPAI), also known as bird flu. It's a reassortment strain that originated from the H5N1, H7N9, and H9N2 subtypes.

This latest outbreak is part of a broader epizootic that has swept across the United States, affecting not only poultry but also wild birds, mammals and humans.