Via the BBC: Ebola outbreak: Six surprising numbers.
The ones that stood out to me were:
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1 in 50 Liberian health workers infected
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90 days without sex for survivors of Ebola (The Ebola virus can remain present in semen for a long time. Experts say it is best for men who are recovering from the disease to avoid sex altogether – or make sure they use a condom – for 90 days.).
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1.7 people infected by each Ebola sufferer in Liberia.
The first and last struck me because they speak to the probabilities of spreading the disease (especially given the hysteria at times here in the US). The middle number was interesting only because I had never heard it before (and because it also speaks to possible transmission over a long period of time).
Looking for more information on the last number lead me to this NPR piece: No, Seriously, How Contagious Is Ebola?
The reproduction number, or “R nought,” is a mathematical term that tells you how contagious an infectious disease is. Specifically, it’s the number of people who catch the disease from one sick person, on average, in an outbreak.*
Take, for example, measles. The virus is one of the most contagious diseases known to man. It’s R0 sits around 18. That means each person with the measles spreads it to 18 people, on average, when nobody is vaccinated. (When everyone is vaccinated, the R0 drops to essentially zero for measles).
At the other end of the spectrum are viruses like HIV and hepatitis C. Their R0s tend to fall somewhere between 2 and 4. They’re still big problems, but they spread much more slowly than the measles.
And that brings us back to Ebola. Despite its nasty reputation, the virus’s R0 really isn’t that impressive. It typically sits around 1.5 to 2.0.
This is graphed out in the piece:
(The measles info also underscores the problems associated with the anti-vaccine movement).
