The Ebola epidemic in West Africa has now claimed 8,153 lives, according to new data released by the World Health Organisation on Monday.

The United Nations' public health arm also reported that cases now stand at 20,656, with victims concentrated in Sierra Leone, Liberia and Guinea.

Sierra Leone, with over 9,700 cases and more than 2,900 deaths as of January 3, is currently the country with the highest number of infections. Liberia, which used to be the worst-affected nation, has seen a decrease in the transmission of the virus, which first struck in Guinea in early 2014.

In September last year, the WHO's worst-case scenario projected 20,000 Ebola cases by mid-November, but thanks to international efforts to combat the disease, the spread of the virus has stalled somewhat.

Still, the end is far off. Anthony Banbury told reporters in Accra, where the UN Ebola Emergency Response mission is based, that the agency is nowhere close to stopping the outbreak.

"We've done a lot in 90 days in a very successful response but we have a long and difficult way to go," Banbury said.

"It's going to go on for not just weeks but some months more," he added. "But I believe we will do it in 2015 and we're going to do it by working very closely not just with governments of the countries but the communities."

Meanwhile, eight people have died from the hemorrhagic fever in Nigeria, six from Mali, and one in the United States. Spain and Senegal had one case each but no fatalities.

Britain was the latest to report a confirmed Ebola case. The nurse who was diagnosed with the disease had recently returned from Sierra Leone. She was said to be in a critical but stable condition on Monday.

Two other health workers in the US and Germany have also been placed under observation.