On Ebola, death rates, misunderstanding and fear

The current Ebola outbreak has a personal element for me, seeing as a dear friend is working as an epidemiologist in Sierra Leone. You can read her account of what she’s doing there on the GroundUp website, and I’d encourage you to do so – as bad as this outbreak is, it would be far worse without the courageous work of people like her, and the least we can do is to become informed about the magnitude of the problem and the sacrifices people are making to address it.

Apparently, the Congo outbreak of Ebola in 2003 is the most virulent to date, but comparisons between various terrifying things provide little comfort for anyone impacted by any one of those things. Also, comparisons can be grossly misleading. Take this chart published by Vox as an example:


As 6000 rightly points out, context matters, and it’s obscene that so many people are dying of things that are relatively easily preventable. But even though there’s nothing false (that I know of) in the graphic above, it’s rather misleading.

Ebola outbreaks are relatively rare, and the chart above compares only 2014 deaths from Ebola with total estimated deaths over some (unknown) timespan. Represented this way, HIV/AIDS deaths dwarf Ebola deaths – but what if we compared HIV/AIDS deaths in 2013 (for Guinea, Sierra Leone and Liberia only) with the 4 000 Ebola deaths represented above?


Then we have an image that looks something like the one above, which makes it plain that if Ebola were a constant (like many of the causes of death in the Vox image), it would be sitting five or 6 positions from the top in that Vox image, rather than being something you need a magnifying glass to find.

What’s more, the total number of cases currently numbers over 8000, and the fatality rate of Ebola is around 70%. So another 5600 might die, meaning that Ebola is likely to kill just as many people in 2014 as HIV/AIDS did in 2013.

The comparison also obscures the fact that not everyone with HIV/AIDS passes it on to someone else, whereas the reproductive number (the average number of cases that each infected person causes) for Ebola is sitting at an estimated 1.4 – 1.8. On average, every case of Ebola is currently creating at least another case.


The epidemic will slow down and later end as epidemiologists get the reproductive rate to drop below 1, and that’s why people like Kathryn (the epidemiologist linked at the top) are doing what they are doing. And what they are doing isn’t easy – read this piece by a Hazmat-trained hospital worker to see how difficult it is to even wear the protective clothing one has to wear, never mind dealing with the paranoia of not trusting that you can touch anything or anyone, or fearing that your food might kill you (to make matters worse, Lassa fever, spread by rats via the food supply, is currently on the increase too).

We have no cases in South Africa.

Thank you to all those who are helping to keep it so.

By Jacques Rousseau

Jacques Rousseau teaches critical thinking and ethics at the University of Cape Town, South Africa, and is the founder and director of the Free Society Institute, a non-profit organisation promoting secular humanism and scientific reasoning.