The West African state of Senegal became the fifth country to be touched by the world’s worst Ebola outbreak on Friday.

The deadly virus has defied efforts by governments to control it, prompting the leading charity fighting the outbreak Medicines Sans Frontiers to call for the UN Security Council to take charge of efforts to stop the epidemic.

At least 1,550 people have died of Ebola and more than 3,000 have been infected since the virus was detected in the remote jungles of southeastern Guinea in March, and quickly spread across the border to Liberia and Sierra Leone.

The World Health Organisation warned on Thursday the actual number of cases could be up to four times higher and said that a total of 20,000 people could be infected before the outbreak ends.