>H5N1 mutates rapidly and has a documented propensity >to acquire genes from viruses infecting other animal >species.
>The spread of infection in birds increases the >opportunities for direct infection of humans. If >more humans become infected over time, the likelihood >also increases that humans, if concurrently infected >with human and avian influenza strains, could serve as >the “mixing vessel” for the emergence of a novel >subtype with sufficient human genes to be easily >transmitted from person to person. Such an event would