OK, this is kind of scary:

Robert G. Webster is one of the few bird flu experts confident enough to answer the key question: Will the avian flu switch from posing a terrible hazard to birds to becoming a real threat to humans?

There are "about even odds at this time for the virus to learn how to transmit human to human," he told ABC's "World News Tonight." Webster, the Rosemary Thomas Chair at St. Jude Children's Research Hospital in Memphis, Tenn., is credited as the first scientist to find the link between human flu and bird flu.

"Society just can't accept the idea that 50 percent of the population could die. And I think we have to face that possibility," Webster said. "I'm sorry if I'm making people a little frightened, but I feel it's my role.

Emphasis added.