According to an article here: http://www.who.int/mediacentre/news/ebola/14-october-2014/en/, the World Health Organization has concluded that 95% of confirmed Ebola cases have an incubation period in the range of 1 to 21 days, while 98% have an incubation period that falls within the 1 to 42 day interval. So from 21 to 42 days the probability of a quarantined person not having Ebola goes up another 3%.
Dallas is only confining potential Ebola-exposed individuals to a 21 day quarantine. This means someone has decided that the additional 3% certainty is not worth an additional 21 days of quarantine. Said person could be at the CDC because the 21 day quarantine recommendation comes from the CDC.
Just understand that it is entirely possible for some of the individuals released from quarantine in Dallas to still develop Ebola. For the first group quarantined, the 42-day deadline is November 10, while for the second group, that date is Friday, November 28. Perhaps we should delay Thanksgiving by one day this year.
This is a continuing series of blog posts on the Ebola outbreak in the Dallas area. Please subscribe to this blog for notice of future posts.