World Health Org. Says Ebola Can Incubate Longer Than 21 Days

According to the CDC, if you have been exposed to Ebola and don't show symptoms for 21 days, it means your free of the disease.  Well, maybe they should talk to the World Health Organization.  Their review of studies shows that, while 95% of Ebola infected patients show symptoms within 21 days, another 3% won't present any symptoms for as long as 42 days.  Their "Ebola situation assessment - 14 October 2014" on incubation periods reads as follows:

Recent studies conducted in West Africa have demonstrated that 95% of confirmed cases have an incubation period in the range of 1 to 21 days; 98% have an incubation period that falls within the 1 to 42 day interval.

Clearly, some 3% of all those healthcare workers, airline passengers, and family/friends of Thomas Duncan might not fall ill for well past 21 days and shouldn't be given a clean bill of health until a full 42 days has lapsed.  Again, the CDC should err on the side of caution when dealing with this disease.

Reference:

World Health Organization: Ebola situation assessment - 14 October 2014: http://www.who.int/mediacentre/news/ebola/14-october-2014/en/