The previous post, based on July-August 2014 Disease Outbreak News from WHO, has shown that the Ebola outbreak in West Africa follows an exponential dynamics. New data from early September, now including a confirmed case from Senegal and many more from other countries in West Africa, still display the same exponential increase, with a doubling of cases each month.
If you compare the new plot with the plot in the previous post, you see that I could have obtained the accurate position of the new September point by linear extrapolation in the logarithmic plot. A simple interpretation of the sustained exponential increase is that so far the measures introduced in the outbreak area are ineffective.
A promising development is that Sierra Leone, one of the countries most severely affected by the outbreak will introduce a lock-down later in September. If the lock-down will be effective, it will show up in our logarithmic plot as a deviation from the straight line to a curve with a decreased slope. (Note added: Medecins Sans Frontieres says that the measure may be not helpful.)
There is an instructive wikipedia article on this outbreak. A key factor facilitating the spread of Ebola is probably “extreme poverty” (including amongst many other things a lack of science-based education). Somehow, we all know this, and we know how we could do better.