By the time the DRC declared its latest Ebola outbreak on 15 May, it may already have been raging for months. In Mongbwalu, families died one after another, the cemetery struggled with up to 20 burials a day, and health workers fell ill and fled. A new investigation suggests the outbreak began in January—and could have been detected much earlier. My story in Science: https://www.science.org/content/article/exclusive-congo-s-ebola-epidemic-started-least-4-months-it-was-detected