Ebola Virus Outbreak. Is It a Black Swan?

The 2014 Ebola outbreak is far worse than previous outbreaks dating back to 1976. One look at the chart below shows you have unprecedented the current outbreak is. While the chart is already outdated the difference between Ebola 2014 and every other outbreak is clear. We must make every effort to contain the outbreak to West Africa. An outbreak in developed countries would overwhelm even advanced medical facilities.

Ebola outbreaks
All Ebola Outbreaks Since 1976

The Ebola Outbreak — A Black Swan

A friend recently asked us whether the massive Ebola outbreak in West Africa could be regarded as a “black swan” in the sense of Nassim Taleb’s definition of the term. After thinking it over, we concluded that yes, it can definitely be characterized as one. Evidently, something is very different about this year’s outbreak compared to previous ones, and a number of unexpected developments have occurred. Chief among them is that a hitherto firmly held belief had to be abandoned. It was thought that the very thing that that makes the illness rather terrifying, namely its high mortality rate, helped in containing outbreaks.

We can definitely state that the current outbreak is anything but “well contained”. Below is a statistical table that shows all Ebola outbreaks since the discovery of the disease in 1976. Note that this graphic is already dated by now — the 2014 event has literally “gone off the chart” in the meantime. Even so, this graphic gives a good impression of how small the previous incidences of Ebola outbreaks were by comparison.

From a statistical viewpoint, the 2014 outbreak definitely must be regarded as a “black swan” — it was hitherto held to be impossible for the illness to propagate in such fashion (source: news.au.com)
Another way of looking at the “black swan” quality of the current outbreak is its geographical spread. All previous Ebola outbreaks were confined to a few isolated locations at most, mainly because they occurred in remote villages in the bush. As a result sick (and therefore infectious) people simply didn’t manage to reach any other villages to spread the virus further. Moreover, since also many of those who catch the illness quickly die, the virus was thought not to propagate very easily. Death is obviously the ultimate impediment to mobility (the dead do however remain infectious for quite some time).
The fact that the outbreak already has “black swan” qualities makes it more likely that a few other strongly held beliefs could also turn out to be wrong. There is already an intense debate over how the virus actually moves from person to person. Given that it is present in sputum, a number of virologists have stated that if one were for instance bathed in a gentle spray of saliva emitted by a coughing and sneezing person that has been infected, one will probably catch it. In fact, a recent warning issued by the Center for Infectious Disease Research and Policy is mainly noteworthy for its admission regarding the uncertainties about possible transmission vectors.

It recommends that health care workers be fitted out with proper respirators to ward off infection via aerosol particles.
Before hearing about this, we remarked as follows in a recent email conversation: Even considering the low standards of hygiene and certain cultural idosyncracies that make it more likely for the disease to spread in African countries, it seems not as difficult to get infected as was generally held. One must also keep in mind that the official numbers almost certainly understate the number of infected people by a fairly big margin — many people reportedly get infected and simply die without ever making it into the statistics.

The progression of the outbreak shows that many hitherto widely accepted nostrums about Ebola and the likelihood of it spreading beyond a fairly small group of people have proved wrong. There is therefore possibly one more article of faith that may prove wrong as well, namely that there is no reason to worry that it could spread in developed countries.
What if it did?..

More Information and Charts: Ebola Outbreak