Few influenza viruses are as widespread and adaptable as avian influenza viruses, and scientists are not entirely sure why.
In a new commentary published online in Emerging Infectious Diseases, two leading influenza experts from the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, examine how the evolution of proteins found on the surfaces of flu viruses has impacted their ability to infect migratory birds and poultry and cause avian disease.