The recent flare-up of Ebola in Sierra Leone has ended, leaving no confirmed cases of the virus in West Africa, the World Health Organization (WHO) said.
More than 3,500 people have died of Ebola in Sierra Leone since the outbreak began in late 2013.
WHO said on Thursday that the country was free of the epidemic after it marked 42 days since the last person confirmed to have Ebola in Sierra Leone tested negative for a second time.
"Today marks another milestone in the country's effort to defeat Ebola," WHO said in a statement, commending the country's response swift response to the latest outbreak.
"From nurses, vaccinators and social mobilizers to contact tracers, counsellors and community leaders, Sierra Leoneans in affected districts mobilised quickly and their involvement and dedication was instrumental and impactful."
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Sierra Leone was declared free of Ebola transmission on November 7 last year, but two cases have emerged since then: in early January, a 22-year-old woman was taken ill near the Guinean border and died days later, and her aunt was infected soon afterwards.
The WHO refers to these isolated cases as "flare-ups" but maintains the original "chains of transmission" have been stopped in Guinea, Liberia and Sierra Leone.
Guinea was declared free of the virus in December, while Liberia was given a clean bill of health in January.
WHO said, however, that the three worst-affected countries are still at risk and must remain on high alert and ready to respond.
A country is declared Ebola free 42 days after the recovery or death of the final patient and if there are no new infections.
The Ebola outbreak in West Africa has claimed the lives of more than 11,300 people, according to WHO.
