In a previous post I briefly discussed Haitian folklore about zombies (quite different to zombies in Western popular culture, which are largely based on the film Night of the Living Dead). In particular I mentioned Wade Davis’ theories that there’s some truth to the idea that Haitian bokors can turn people into zombies.
Anyway, I wanted to add that these ideas would be particularly useful for Carcosa, which tries to combine horror with a non-supernatural explanation for everything.
As I said before, this is a good introduction to the subject. But Wade Davis wrote two books about his investigations in Haiti: The Serpent and the Rainbow and Passage of Darkness. The Serpent and the Rainbow was adapted into a film, but the adaptation doesn’t seem to have kept much of the original book.