The weekly number of Ebola cases in the three worst-hit West African countries has increased for the first time this year, according to the World Health Organisation (WHO).

A total of 124 new cases were recorded in Guinea, Liberia and Sierra Leone in the week ending 1 February, including 80 in Sierra Leone, the most affected West African nation.

Guinea recorded around 39 new cases, while the remaining five cases were reported in Liberia.

WHO was quoted by AFP as saying: "Continued community resistance, increasing geographical spread in Guinea and widespread transmission in Sierra Leone, and a rise in incidence show that the (Ebola) response still faces significant challenges."

The latest Ebola situation report follows just days after the WHO said that there were 99 confirmed cases in the week ending 25 January, the lowest tally since June 2014.

"A total of 124 new cases were recorded in Guinea, Liberia and Sierra Leone in the week ending 1 February."

In the latest statistics, 8,981 people have died infected with the virus, of the total 22,495 cases in nine countries.

Guinea recorded 2,975 cases, including 1,944 deaths, while Liberia reported a total of 8,745 cases, including 3,746 deaths.

In October 2010, WHO warned West Africa may face up to 10,000 new Ebola cases per week within two months, due to the increasing number of patients.

In November 2010, the UK Department for International Development (DFID) and the Wellcome Trust provided £1.34m from a joint fund for five research projects, to combat the Ebola outbreak in West Africa.

In December 2014, GlaxoSmithKline (GSK), University of Oxford, Centre Hospitalier Universitaire Vaudois in Lausanne and the Bernhard-Nocht Institute have formed a new European consortium to help further advance development of a candidate vaccine against Ebola.

Image: Electron micrograph of an Ebola virus virion. Photo: courtesy of CDC/Cynthia Goldsmith.