What Bill Gates is afraid of

⁣What's likeliest to kill more than 10 million human beings in the next 20 years? It's probably not what you'd think.

There's something out there that's as bad as war, something that kills as many people as war, and Bill Gates doesn't think we're ready for it.

"Look at the death chart of the 20th century," he says, because he's the kind of guy that looks at death charts. "I think everybody would say there must be a spike for World War I. Sure enough, there it is, like 25 million. And there must be a big spike for World War II, and there it is, it's like 65 million. But then you'll see this other spike that is as large as World War II right after World War I, and most people, would say, 'What was that?'"

"Well, that was the Spanish flu."

In a 1990 paper on "The Anthropology of Infectious Disease," Marcia Inhorn and Peter Brown estimated that infectious diseases "have likely claimed more lives than all wars, noninfectious diseases, and natural disasters put together."

Infectious diseases are our oldest, deadliest foe.

And they remain so today. "In a good year, flu kills over 10,000 Americans," says Dr. Thomas Frieden, director of the Centers for Disease Control and Prevention. "In a bad year, it kills over five times that. If we have a pandemic, it will be much worse. People think the H1N1 flu wasn’t so bad. But more than 1,000 American kids died from H1N1!"