WHO says 13,000 is an underestimate of Ebola: as many as 20,000 by the end of November

In fact, the current epidemic sweeping across the region has now killed more than all other known Ebola outbreaks combined.
Up to 4 November, 4,960 people had been reported as having died from the disease in five countries; Liberia, Guinea, Sierra Leone, Nigeria and the United States. A further death has been reported in Mali.
The total number of reported cases is in excess of 13,000.
The World Health Organization (WHO) admits the figures are underestimates given the difficulty collecting the data and warns there could be as many as 20,000 cases by the end of November if efforts to tackle the outbreak are not stepped up.
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BBC News - Ebola: Mapping the outbreak

20,000 cases by the end of November actually makes sense using the 10 times formula of the number of cases increasing from July to October 2014. During this period I believe the approximate increase was from about 1300 or 1400 cases to 13,000 now. That there would be 20,000 by the end of November (and of course this would also be an underestimate of cases because it isn't safe to go where it is the worst because there isn't food or medicine there anymore.

So, in some areas where people are afraid to go people are dying of both Ebola and Starvation at the same time now because in some areas all infrastructure of working and feeding people has completely collapsed.

So, the number of actual cases doubling in one month would make sense using this 10 times formula for every 4 months. In one month it would naturally double and by 4 months from October it would be 100,000 if this formula holds true at this point. 

One of the interesting things regarding this. The United Nations representative for the U.S. was on the Daily Show last night and said there were only hundreds of volunteers fighting Ebola in Africa now. However, what she said is they don't now need hundreds, they need thousands of volunteers and they don't have them. 

Given this statement it is now possible that the 10 times formula of cases might continue to 100,000 by January or February because the response is too slow and governments might not be able to respond in time now because it is just moving too fast to stop with present methods in place. Even with Herculean efforts by nations I'm not sure it can be stopped now because nations just are moving too slowly at this point to stop this.