Very worrying, there is a 2 week incubation period during which there are no symptoms. It does not become infectious until the symptoms appear so someone can get on a plane and be anywhere in the world before they know they have it, then it is 95% fatal.
The Ebola virus is spread from person to person through contact with infected blood and body fluids. Doctors also believe that it passes through the air when an infected person coughs or sneezes. Hospital workers are at high risk for Ebola during outbreaks, because they come into contact with blood and body fluids when they care for infected patients. Infected patients often die very quickly, limiting the opportunity for the virus to be transmitted to many other people. This may be why Ebola outbreaks have not become widespread.