PREVIEW: Epidemiology of guns by The World

Next time on The World, an American doctor noticed that gun crimes follow a pattern

The same pattern he saw treating tuberculosis in Africa.

Gun violence, he says, spreads like an infectious disease.

CLIP: "Someone has picked this up from someone else, and they pass it on to someone else, and pass it on to someone else."

Now he's using disease prevention tools to contain gun violence in America.

That's on The World.