More than 8,000 people have died of Ebola in the three worst-affected countries of Guinea, Liberia and Sierra Leone, the World Health Organization (WHO) said on Monday.

Reporting the latest figures in the year-long epidemic, the U.N. health agency said 8,153 people had died among 20,656 known cases of the hemorrhagic fever in the three countries.

Sierra Leone recorded the biggest rise in fatalities, with 88 since the previous figures were issued on Jan. 2.