The World Health Organization (WHO) has described the months long Ebola outbreak in West African countries, that has killed more than 100 people mostly in Guinea and Liberia, as the most challenging outbreaks of the disease the international community has ever faced, euronews reported.

Most of the deaths in Guinea and Liberia and suspected cases in Sierra Leone, Mali  and Ghana were linked to the Ebola virus, which may have begun in January, said Tarik Jasarevic, a spokesman for the World Health Organization.

WHO Officials however said tests showed suspected cases in Ghana and Sierra Leone were not Ebola. It added that two of nine cases in Mali were also cleared.