Rye Ergot
Ergot is a fungus blight that forms hallucinogenic drugs in bread. Its victims can appear bewitched when they're actually stoned.
Ergot thrives in a cold winter followed by a wet spring. The victims of ergot might suffer paranoia and hallucinations, twitches and spasms, cardiovascular trouble, and stillborn children. Ergot also seriously weakens the immune system.
One theory about the witchcraft hysteria in Salem, Massachusetts in 1692 is that it was caused by Rye Ergot.
See:
- Clues and Evidence (from the Secrets of the Dead PBS Series)
- Rye Ergot and Witches by John H. Lienhard
- Ergot Poisoning - the cause of the Salem Witch Trials