The decision by WHO's Ebola emergency committee comes following flare-ups that emerged in Guinea, Liberia and Sierra Leone after authorities declared virus transmission over. The new cases sometimes were publicized only hours after the public announcements were made.
"Complacency at this stage would be completely wrong," said Robert Steffen, the committee's vice chair.
The announcement puts an end to the international emergency declaration that has been controversial. An Associated Press investigation found that WHO initially delayed making the declaration — similar to an SOS signal — on political, economic and religious grounds.
Tuesday's announcement also comes as the organization fights the Zika virus that has prompted concern in the Americas. Steffen said the battle against Zika in no way dictated the committee's decision to declare the Ebola emergency over.
While there have been flare-ups of new cases, health authorities said Tuesday those were not linked to the original chains of transmission dating back to December 2013.
"We know that little clusters will continue to flare up. That will be normal life just as in previous decades, there have been every now and then, outbreaks of Ebola in various parts of sub-Saharan Africa," Steffen said.
More than 11,000 people have died mostly in Guinea, Liberia and Sierra Leone since December 2013. There are currently no known cases in Liberia or Sierra Leone, though Guinea recently reported two confirmed and three probable cases. Authorities are now monitoring nearly 1,000 contacts of the sick.