A LOT we don’t know about this bugger. Could be a small population has a weak genetic link which allows this beast to fester. As awful as it is, I am surprised that MILLIONS in Africa didn’t perish from it, which might mean that it’s been around for eons and a large segment is immune from it. Perhaps in the isolated villages in which it was first “discovered” in 1976, the isolation in which these villagers lived in Zaire/Congo and the lack of new “blood” hampered their immune systems and they had no resistance.
See link in 101.
Five months, guy was cleared, gives ebola to a woman via sex.
After five months.
I think the main reason is remoteness. It killed far faster than people could walk. Things have changed, with transportation you get a bigger spread.