"Influenza, Human prevention & control." . . "Influenza, Human epidemiology." . . . . . . . "Steve Kroft travels to Asia, tracking H5N1, the avian flu, a bird virus ravaging poultry there. It has on rare occasions infected humans, killing half of its victims. Since humans have no immunity to the virus, health officials are concerned, not only in Asia, but in the U.S. as well." . . . . . "Chasing the flu" . . . . . . . . "Influenza A Virus, H5N1 Subtype." . . . . "Disease Outbreaks prevention & control." . .