A health-care worker takes a blood sample from an Ebola survivor as part of a study on the disease in Monrovia, Liberia, June 17, 2015. James Giahyue/Reuters

The World Health Organization Saturday declared Sierra Leone Ebola-free. WHO said it has been 42 days -- two Ebola virus disease incubation cycles -- since anybody in the country has been confirmed as having the disease, which is marked by fever and severe internal bleeding.

“Since Sierra Leone recorded the first Ebola case in May 2014, a total number of 8,704 people were infected and 3,589 have died, 221 of them health-care workers, all of whom we remember on this day,” said Dr. Anders Nordstrom, WHO representative in Sierra Leone.

The declaration does not mean the end of monitoring in Sierra Leone. A 90-day period of enhanced surveillance will run through Feb. 5 to ensure early detection of any recurrence of the disease, which is spread through contact with infected body fluids.

“We now have a unique opportunity to support Sierra Leone to build a strong and resilient public-health system ready to detect and respond to the next outbreak of disease, or any other public-health threat,” Nordstrom said.

Nordstrom credited the Sierra Leone government and the cooperation of the country’s populace for halting the outbreak.

“The world had never faced an Ebola outbreak of this scale and magnitude, and the world has neither seen a nation mobilizing its people and resources as Sierra Leone did,” he said. “The power of the people of Sierra Leone is the reason why we could put an end to this outbreak today. … The Ebola outbreak has decimated families, the health system, the economy and social structures. All need to recover and heal.”

The Ebola outbreak in West Africa was detected in 2014, and by last month it had claimed at least 11,313 lives among 28,575 diagnosed cases. WHO has said it believes those numbers are understated. The countries most affected by the outbreak were Guinea, Liberia and Sierra Leone. Cases also were reported in Italy, Mali, Nigeria, Senegal, Spain, the U.K. and the U.S., the Centers for Disease Control and Prevention reported.