Hours after the World Health Organization declared an end to the Ebola outbreak that has plagued West Africa for some two years, officials in Sierra Leone on Thursday confirmed a new death from the virus, BBC reports. The WHO has warned, the BBC notes, that flare-ups are expected. "We are now at a critical period in the Ebola epidemic as we move from managing cases and patients to managing the residual risk of new infections," WHO's Dr. Bruce Aylward tells NPR.
Ebola can survive in people for nine months or more, according to reports. An "Ebola-free" declaration is made after no cases are reported for 42 days, which equals two of the virus's 21-day incubation cycles, per NPR. The Sierra Leone death happened earlier this week, in the northern Tonkolili district. Health officials are trying to track down anyone who had contact with the victim. Across the region, Ebola has killed more than 11,000 people since December 2013, according to the BBC.