New research has shown that Ebola survivors can relapse and trigger outbreaks at least five years after infection, meaning long-term follow-up of former patients is needed to prevent devastating flare-ups. The AFP news agency reports that scientists already knew Ebola could lie dormant in survivors, who test negative because the virus is in tissue rather than circulating in the blood. But analysis of an outbreak this year in Guinea, published on Wednesday in the journal Nature, found these “virus reservoirs” appear able to awaken and cause new infections and transmission years on.