Ebola in West Africa — a look at recent data (UPDATE)

Update on confirmed Ebola cases in West Africa with new data from September 2014. Blue: confirmed cases of Ebola infection, red: confirmed deaths. Note that vertical axis is scaled logarithmically.

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.

Ebola in West Africa — a look at recent data

Confirmed cases of Ebola in West Africa in July and August 2014. Red: confirmed accumulated infections, blue: confirmed accumulated deaths.
Confirmed cases of Ebola in West Africa in July and August 2014. Red: confirmed accumulated infections, blue: confirmed accumulated deaths. The vertical count axis is scaled logarithmically. Figure by hoffmann based on data published by the World Health Organization, Creative Commons License.

The World Health Organisation releases so-called Disease Outbreak News (DONs) for a number of infections, including Ebola Virus Disease. The Ebola DONs referring to the current outbreak in West Africa (Guinea, Liberia, Nigeria, and Sierra Leone) show a sustained, approximately exponential increase in the number of confirmed Ebola infections and deaths in (see Figure) during July and August 2014. There are no clear signs of a subsiding of the outbreak. In the past two months, the number of confirmed cases has roughly doubled each month. The death rate is stable at about 50%. Bad.

(See also update of post.)