The ebola conundrum: Finding its source in nature

A scary problem lurks beyond the frenzied efforts to keep people from spreading ebola: No one knows exactly where the virus comes from or how to stop it from seeding new outbreaks.

Ebola has caused two-dozen outbreaks in Africa since it first emerged in 1976. It is coming from somewhere — probably bats — but experts agree they need to pinpoint its origins in nature.

That has had to wait until they can tame the current outbreak, which has claimed more than 1,100 lives in four countries — the worst toll from ebola in history.