[cynwoody]

The incubation period for ebola is 2-21 days, usually 10 days.

Half become ill before 5.5 days; half after.

Here's a chart from a CDC report, showing the distribution of incubation times across 5,000 cases:

The median incubation is 5.5 days. The mean is 6 days. And 21 days is the 99th percentile, not the limit, as can be seen from the chart.

Here's another link (to the WHO), which claims that 21 days is only the 95th percentile, 42 days is the 98th percentile, and 2% get lost in the jungle or something. Hopefully, the CDC is right.

[Ray76]

I based my comment on my recollection of an article in the NE Jour. of Medicine (http://www.nejm.org/doi/full/10.1056/NEJMoa1411100#t=abstract). It turns out the incubation period is greater than I recalled, the article states “The mean incubation period was 11.4 days”. I don’t intend to be argumentative, only to show the basis for my comment.