Ebola facts - WORLD HEALTH ORGANIZATION'S LATEST UPDATE
According to the World Health Organization (WHO), as of October 22, there were at least 9,911 cases of the Ebola virus and 4,546 deaths in the West African countries of Guinea, Liberia and Sierra Leone.
The WHO estimates its figures by taking the numbers of confirmed cases and multiplying them - from Guinea by 1.5, from Sierra Leone by 2 and from Liberia by 2.5 - to account for under-reporting.
The outbreaks of Ebola virus disease (EVD) in Senegal and Nigeria were declared over on October 17 and October 19, respectively.
A national EVD outbreak is considered to be over when 42 days (double the 21-day incubation period of the Ebola virus) has elapsed since the last patient in isolation became laboratory negative for EVD.
The virus was introduced into Nigeria on July 20 when an infected Liberian man arrived there by airplane. The man, who died in hospital five days later, set off a chain of transmission that infected a total of 19 people, killing seven.