The Geneva-based body says the total number of confirmed, probable and suspected deaths from the disease in the three most affected countries reached 7,989 by Dec. 31.
The United Nations agency said Friday that 2,827 deaths had been reported from Sierra Leone, some 3,423 from Liberia and 1,739 from Guinea. It said those countries had a total of 20,381 cases to date.
The current outbreak, which began about a year ago, has also claimed some 15 lives elsewhere.
The Ebola virus causes a form of hemorrhagic fever with a high mortality rate. It can be transmitted through bodily fluids such as blood.