US health officials are carefully monitoring a bird flu outbreak in Western Asia. The head of the Centers for Disease Control warns the virus has the potential to mutate and kill tens of millions worldwide.
Scientists are worried because humans have not built up immunity to the strain of avian virus that's killing nearly three of every four infected people. A special "influenza team" is watching emerging strains, in order to come up with a vaccine to fight it.
CDC Dr Julie Gerberding: "We are, however, very concerned about avian flu in Asia. There are more pigs, people, and poultry in that environment than we've ever seen before. That is the formula for emergence of new flu strains."
The Asian strain of the flu has not shown up in the US.
Oklahoma health officials say the strains now showing up in Oklahoma, are protected by this year's vaccine; however, flu season has not yet peaked.