The U.N. health agency said Friday that Sierra Leone's government was moving rapidly to contain the new threat, but it was not clear how the 22-year-old woman who died may have contracted Ebola. His comments were reported by the Associated Press.
He said: "We can anticipate future flare-ups of Ebola in the coming year".
A woman's body has tested positive for Ebola in Sierra Leone, an official said, the day after the World Health Organisation declared the outbreak over in west Africa. Countries are then placed on a 90-day heightened surveillance.
The victim reportedly fell ill after returning from Kambia district, also in the north, which is a region close to the border with Guinea, where the epidemic that erupted in 2014 began. Authorities are tracing her contacts and have dispatched teams to the area for investigations.
Another death by the Ebola virus was confirmed Jan. 15 in Sierra Leone.
The news comes only a day after officials declared the entire epidemic over in West Africa. Health officials in Sierra Leone are seeking out anyone who the victim had contact with recently, and quarantines are a possibility.
The WHO had said Thursday a two-year Ebola outbreak that killed more than 11,000 people and triggered a global health alert was over, with Liberia the last country to get the all-clear. Sierra Leone was declared Ebola-free Nov. 7 and Guinea followed suit Dec. 29.
"While this is an important milestone and a very important step forward, we have to say that the job is still not done", said Rick Brennan, WHO director of emergency risk assessment and humanitarian response, at a news conference in Geneva. Men who survive Ebola are known to emit viruses in their semen for months after their recovery. As well as screening for persistent virus, they will need medical and psychological care, and support to help them return to normal life in their families and communities, who will also need education and help to reduce stigma and minimize risk of Ebola virus transmission.
More than 11,200 people have died from Ebola since an epidemic broke out in December 2013 in Guinea.
Liberia and West Africa were formally declared Ebola-free by the World Health Organization on Thursday.
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The crash is still under investigation but the driver was arrested for driving under the influence of alcohol, the CHP said. He said he feels better and has been taken off a machine that helped him breathe, but remains in intensive care.