Public health officials fear that a new flu pandemic may be on its way. A strain of bird flu known as H7N9 originated among poultry in China in 2013 and evolved into a form that can infect humans. It reportedly kills 40 percent of those who become ill. It has not yet spread beyond China and is not yet contagious from human to human, with only about 1,600 reported cases so far. However, should it mutate into a form that can be spread between people, the threat could be worldwide.