The World Health Organization (WHO) has warned that Ebola infections will treble to 20,000 by November if efforts to tackle the outbreak are not stepped up.
A new analysis suggests about 70% of those infected have died, higher than the 50% previously reported.
There have been 2,800 deaths so far and the disease remains “a public health emergency of international concern”, the UN agency said.
Trials of experimental drugs are being fast tracked in West Africa.
Meanwhile, more information on the spread and likely scale of the epidemic has emerged.
Projections published in The New England Journal of Medicine suggest by early November there will have been nearly 20,000 cases.
A new analysis of confirmed cases suggests death rates are higher than previously reported at about 70% of all cases.
And WHO scientists said numbers were predicted to rise exponentially, raising the possibility that the disease could become endemic [regularly found] in West Africa.
Nearly all of the deaths in the world’s worst Ebola outbreak have been recorded in Guinea, Liberia and Sierra Leone.
Dr. Christopher Dye, Director of Strategy for WHO, said projections suggest “unless control measures – including improvements in contract tracing, adequate case isolation, increased quality of care and capacity for clinical management, greater community engagement, and support from international partners – improve quickly, these three countries will soon be reporting thousands of cases and deaths each week”.
Dr. Christopher Dye, co-author of the study, called for “the most forceful implementation of present control measures and for the rapid development and deployment of new drugs and vaccines”.
It came as The Wellcome Trust charity announced that experimental drugs would be tested in West Africa for the first time.
Several drugs are under development, but they have not been fully tested and most are in very short supply.
They include the drug ZMapp, which has been given to a handful of infected health workers.
Dr. Peter Horby, of the Centre for Tropical Medicine and Global Health at the University of Oxford, said the first trials could begin in West Africa as early as November.
Dr. Jeremy Farrar, director of the Wellcome Trust, said therapeutics alone were not an answer.