It's been over a year since the worst Ebola outbreak in history began to ravage the West African nations of Guinea, Sierra Leone and Liberia. To date, the highly infectious virus has claimed the lives of nearly 10,000 recorded victims. And although the epidemic's spread has significantly slowed, with patients confined to a shrinking geographic region, there's still no known cure and more than 100 reported new cases each week, according to the World Health Organization. In the interactive map sequence below, Frontline traces the epidemic's spread from its suspected emergence with Patient Zero back in December 2013.