I based the zombies in my fictional world more on Haitian folklore than on the brain-eating ‘viral zombies’ based on Night of the Living Dead that are more popular. I’m not one of those people who think that ‘real’ mythology is better than modern fiction. It was just what I was more familiar with. Zombies in D&D seem to be a mixture of the two: they’re animated corpses rather than living people robbed of their will but, at least in the 1974 rules, salt will thwart them.
Anyway I was vaguely aware that an American had written a book arguing that Haitian bokors really had reduced people to a zombie-like state, but I assumed he was a crank.
It turns out that his name is Wade Davis, he’s actually qualified (Harvard funded his research in Haiti), and his argument is quite convincing. Having read everything I could find on the subject (for a university assignment) I’m unsure whether he’s right or not, but of course that doesn’t matter for the purposes of D&D. You can read one article about it all here.