Is 21 days really long enough for an Ebola quarantine?

Symptoms typically begin to appear after nine days, but the World Health Organization has even recorded instances of a person contracting the disease after 30 days.

A few weeks ago, when Ebola was starting to permeate the news, Haas began to wonder how WHO came to its 21-day quarantine recommendation for Ebola. Haas then compiled all the available data on previous outbreaks. What he found was that, thankfully, there aren’t many data on past outbreaks. In the past, Ebola has affected a few hundred people at a time; not the thousands who have been blighted in the current crisis. The small number of data points means that while health authorities may have a good idea of how long Ebola can remain dormant in the body, they do not know the upper limits of what is possible.

“If I pulled 12 people at random off the street and measured their height,” Haas explained, “and then used the greatest high of those 12 as an index to what the maximum height would be for the human population, I would be incredibly wrong.”