That is a hereditary disease, not infectious. However, the mutation that causes it does grant an ethnicity specific immunity/resistance to malaria. There are a number of ethnicity specific hereditary diseases that confer protection from other diseases that are bad for the host if they get the genes from both parents, but beneficial if they get it from only one.
Another example of this is Tay-Sachs hereditary disease common to eastern European Ashkenazi Jews. A single copy of that mutation will give immunity against TB, but two copies will kill you.
Many other hereditary mutations that protect against infectious disease cause no hereditary diseases on their own, but they are less well-known primarily because there is no nasty side-effects to highlight the existence of an interesting mutation. Hereditary diseases like Sickle Cell Anemia would normally be bred out of a population if it was not for the fact that at some point the mutation also greatly enhanced survivability of the person carrying it.
Remember the rash of biologists that died in mysterious ways right before the war in Iraq? That was post SARS, pre-Marburg.
Once the cave was discovered as the source of Ebola, and elephants as the reservoir, China has Ebola.
H5N1 and this strain of Ebola have a noticeable discontinuity in their sequencing, according to the source article. That says to me "splicing".
You are obviously trained in this field - I'm certainly not - so I'd appreciate your educated opinion: Is this "new" strain natural or manmade?