Ten years ago, on 23 March 2014, Guinea declared an outbreak of Ebola. Ebola outbreaks were known to be dangerous, but small. Not this time, though: it would take two years and more than eleven thousand deaths, before the epidemic was over. Dr Michel Van Herp, a renown Ebola expert even before 2014, looks back at the biggest Ebola outbreak ever, and answers 5 key questions.