In a study published in the Proceedings of the National Academy of Sciences, some North American avian influenza A H7 virus strains have properties that might enhance their potential to infect humans as well as their potential to spread from human to human. To date, most cases of avian influenza infection have come from contact with infected poultry or contaminated surfaces. However, lead author of the study from The Centers for Disease Control and Prevention (CDC) says that the study points to the importance of continued influenza virus surveillance. In another study by the University of Maryland, researchers have discovered that the H9N2 avian flu strain has pandemic potential. Study results indicate that the H9 viruses have the potential to begin spreading among people with just minor mutations. H9 avian influenza is widespread among birds in Asia, the Middle East, Europe, and Africa and while it doesn’t make birds sick, it has affected some humans with a mild illness.