As the U.S. poultry industry continues to deal with highly pathogenic avian influenza virus infection in the Midwest, it is important to reflect on why this virus has spread through a section of the industry and how the poultry industry has prepared itself for control of this disease.
The avian influenza virus that has infected commercial poultry in the U.S. is unusual in several respects. The first unusual characteristic is that it originated in Asia. It is extremely rare for an Asian avian influenza virus to cross the Pacific Ocean and establish itself in birds in North America. How this occurred is not clear, but it may have involved the migration of wild birds across the Bering Sea.