The article goes on to discuss blood clotting as a factor. It makes you wonder if those who are on blood thinners, or who take a daily aspirin to keep their blood thinner, are also at a higher risk.
Well, Ebola has the distinction of causing random and dangerous blood clotting, before it causes rampant bleeding.
Or maybe it just happens to hit people hard that have sickle-cell trait blood problems in their genes.