TheEbolavirus.No-oneknowsexactlywhereitcomesfrombutonethingiscertain-it'soneofthemostvirulentinfectionsknowntoscience.ThisspecialepisodeofHorizonmeetsthescientistsanddoctorsfromallaroundtheworldlookingforthecureandhearsfirst-handaccountsofwhatit'sactuallyliketocatch-andsurvive-thisterribledisease.