A total of 5,800 people were infected with the Ebola virus in the hardest-hit countries, Guinea, Liberia and Sierra Leone, the UN health agency said.
The WHO said that the outbreak response measures will cost at least $1 billion.
The Ebola virus disease (formerly known as Ebola haemorrhagic fever) was first reported in 1976 in Zaire (now Democratic Republic of Congo) and got its name from the river near which the first outbreak occurred.
It is a severe, often fatal illness, with a case fatality rate of up to 90% It is one of the world’s most virulent diseases. The infection is transmitted by direct contact with the blood, body fluids and tissues of infected animals or people. Severely ill patients require intensive supportive care.