http://www.who.int/csr/disease/ebola/overview-august-2014/en/
From WHO's website today:
Barriers to rapid containment of the Ebola outbreak
The Ebola virus is highly contagious, but is not airborne. Transmission requires close contact with the bodily fluids of an infected person, as can occur during health-care procedures, home care, or traditional burial practices, which involve the close contact of family members and friends with bodies. In Guinea, around 60% of cases have been linked to these burial practices, with women, who are the principal care-givers, disproportionately affected. (what about in Sierra Leone and in Liberia?)
The incubation period ranges from 2 to 21 days, but patients become contagious only after the onset of symptoms. As symptoms worsen, the ability to transmit the virus increases. As a result, patients are usually most likely to infect others at a severe stage of the disease, when they are visibly, and physically, too ill to travel.
Italics are mine.