In 1976 a deadly virus emerged from the Congo forest. As swiftly as it came, it disappeared, leaving no trace. Over the four decades since, Ebola has emerged sporadically, each time to devastating effect. It can kill up to 90 percent of its victims. In between these outbreaks, it is untraceable, hiding deep in the jungle. The search is on to find Ebola's elusive host animal. And until we find it, Ebola will continue to strike. Acclaimed science...