Scientists are sounding the alarm: All signs are pointing to the emergence of a new, deadly contagious strain of the flu that will catch the world off-guard. History has shown that flu pandemics occur periodically (the last one was more than 30 years ago), causing widespread illness and death, overwhelming medical systems and wreaking havoc on societies. And flu expert Robert Webster of St. Jude Children's Research Hospital in Memphis, says, “We're overdue.” His team describes this next pandemic as not only inevitable, but imminent.

The greatest concern is a flu virus that would jump the species barrier. In such a case, humans would have no immunity, thus causing a deadly pandemic. Webster continued: “It's knocking at the door. We've seen enough incidence over the last three or four years to make us alarmed.” Bird flu, for example, was unknown before 1997. This year alone, there have been two confirmed incidents of this virus “jumping” to humans—one in Hong Kong, and another in the Netherlands. So far, this virus has yet to mutate into a form that is able to efficiently spread between humans.