Ebola cases could reach 1.4 million by late January 2015, up from the current total of 5,800, according to a new study by a US medical agency.
The US Centers for Disease Control and Prevention (CDC) released a report on Tuesday suggesting that Ebola cases could increase to between 550,000 and 1.4 million in four months, based on several factors including how many people are infected by Ebola carriers.
The report questions whether the official number of deaths recorded by the World Health Organization, 2,800 out of at least 5,800 Ebola cases, has been underreported.
CDC said it is likely that 2.5 times as many cases, or nearly 20,000, have occurred so far.
"Extensive, immediate actions - such as those already started - can bring the epidemic to... a rapid decline in cases," said CDC in a statement.
Sierra Leone, one of the five west African countries effected by the Ebola outbreak, is considering another nationwide lockdown to slow the spread of the disease, following a three-day quarantine last week, in which they say they confirmed 130 cases and are awaiting tests on another 70..
President Ernest Bai Koroma said on local radio on Tuesday that he was "mainly satisfied with the whole process, as it has helped reaching more homes and bringing to the fore many sick people and corpses".
The unprecedented nation-wide lockdown saw visits to more than one million households that were given information on the disease.
"It's important for African governments to innovate and find new ways of getting messages out to the people," David Heymann, an Ebola expert, told Reuters news agency.
Ongoing efforts to tackle the disease may hamper its spread. The report released by CDC does not account for measures recently announced by the US.
The US plans to send 3,000 members of its armed forces to the region as well as training 500 healthcare workers per week.
Nonetheless, experts from the WHO said on Tuesday that the outbreak could reach 20,000 recorded cases as soon as early November if rigorous control measures are not put in place.
In August, the WHO predicted it would take until the middle of 2015 for the virus to strike 20,000.
Meanwhile on Monday, the WHO said that outbreaks in Senegal and Nigeria are "pretty much contained".
The following day on Tuesday, Sierra Leone's army announced that it had "sealed off" its borders with Liberia and Guinea in a bid to halt the spread of Ebola.
Looking to the future, WHO's Director of Strategy Christopher Dye said that "this is a bit like weather forecasting. We can do it a few days in advance, but looking a few weeks or months ahead is very difficult."
Dr. Joel Montgomery, team leader for the U.S. Centers for Disease Control and Prevention Ebola Response Team in Liberia, is dressed in his personal protective equipment while adjusting a colleague's PPE before entering the Ebola treatment unit in Monrovia, Liberia's capital city in this recent photo released on September 16, 2014.