"pre-existent and popularly held African folk beliefs"
Chicken and egg really CS - exorcism has been and continues to be a part of christianity, going back at least to the 2nd century under that name - who is to say which is the most toxic of the "toxic mix"?
The indication is that, far from being a thing of the past, it seems to be enjoying a bit of a renaissance at present.
http://www.dailymail.co.uk/news/article-504969/Popes-exorcist-squads-wage-war-Satan.html
Not suggesting for one minute that 'is 'oliness's lads would take it as far as this tragic incident - but lest we forget.... the same church that was collecting for "little black babies" on the street corners, was also shipping out to Africa their over-enthusiastic paedophiles to get them "out of harm's way".
Jim Carroll