This cold and flu season, the Centers for Disease Control issued a new health alert about a mysterious virus responsible for nightmare scenarios: a child wakes up and his legs don't move. Or he doesn't wake up at all. Enterovirus D-68 hit the U.S. with a vengeance last year mimicking one of the world's most feared illnesses: polio. And the medical mysteries of where it came from and why have yet to be unraveled.
