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Comment by DocSavage | Hacker News Reader

NPR has a good infographic on the infectiousness of Ebola relative to other agents:

http://www.npr.org/blogs/health/2014/10/02/352983774/no-seri...

The problem with averages is they can break down pretty quickly when facing reality. Example from yesterday: I took my kids fishing on a party boat. Lots of kids on the boat. They congregated around the live bait tank. I noticed one kid who was obviously sick. He was coughing constantly all over the place. I watched him cough directly into other kid's faces. And, I am not talking about a gentle cough at all. He coughed on nearly every surface he came into contact with. If this kid was carrying active ebola or something else I would guess twenty to thirty people may have been exposed. I made it a point to have my kids avoid him, yet, in that scenario, there is no way to control exposure. For example, everyone shared one bathroom. With over 50 people onboard, the "about 2" idea is just a suggestion and in two or three weeks it goes exponential.

Yes, I tried to find the irresponsible parent and even asked the captain to make an announcement. He couldn't care less, which further throws off the "about two" rule in the face of reality.

But there's a further difference between the common cold and ebola: a cold spreads through aerosols, so all those kids standing around the sick one are breathing in live virus. Ebola spreads only through infected bodily fluids, so he'd have to be vomiting directly on the other kids for them to catch it. Usually by the time someone is vomiting or bleeding from Ebola, they feel far too sick to go on a fishing trip.

While it's possible that Ebola could mutate and become airborne (this is the plot of the movie Outbreak, after all), scientist believe it pretty unlikely. In humans, it preferentially attacks the gastrointestinal track, and virus loads are pretty low in the respiratory system.

So yes, averages do obscure specific circumstances that affect reality. However, the averages are low because the specific circumstances that would cause high averages are rare.

According to the CDC,

"Although coughing and sneezing are not common symptoms of Ebola, if a symptomatic patient with Ebola coughs or sneezes on someone, and saliva or mucus come into contact with that person’s eyes, nose or mouth, these fluids may transmit the disease."

http://www.cdc.gov/vhf/ebola/transmission/qas.html

yes, but it doesn't get transmitted through the air. You have to literally sneeze on someone not in their general vicinity

Even if that kid had Ebola (which is not respiratory intensive), the number 'about two' would still hold true on average.

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