Victims of ergotism. Pieter Bruegel painting, Louvre.
Ergot poisoning was certainly common in history, there is no doubt about that. But was it responsible for the events that occurred in Salem and what exactly is the evidence that the fungus was involved?
From The Straight Dope - Were the witches of Salem a result of poisoning with ergot fungus?
In 1976 psychology grad student Linnda R. Caporael proposed the ergotism hypothesis, and history professor Mary Matossian elaborated on it in 1982. The core contentions: A cold winter followed by a moist spring and summer prior to the witchcraft hysteria favored the growth of ergot fungus in rye that the colonists were obliged to eat due to crop failure. Ergot contains toxins known to cause convulsions, hallucinations, and other symptoms similar to those reported by the accusers.
Doubters were quick to raise objections: Evidence of a cold winter and crop failure is dubious, and none of the accusers displayed the full array of symptoms needed to support a diagnosis of convulsive ergotism. More importantly, the symptoms appeared only at opportune moments during the trials, strongly suggesting a psychosomatic origin if not fraud. The counterarguments seem to have persuaded most historians, but a credulous 2001 PBS documentary has helped keep conjecture about ergotism alive.
A. Woolf in the Journal of Clinical Toxicology reaches a similar conclusion. Witchcraft or mycotoxin? The Salem witch trials.
The Salem witchcraft trials of 1692 have been studied by many historians looking for the complex social, political, and psychological determinants behind the community-wide hysteria that led to a travesty of justice and the deaths of 20 innocent Puritans. Recently, ergot poisoning has been put forth by some as a previously unsuspected cause of the bizarre behaviors of the young adolescent girls who accused the townsfolk of witchcraft. In this essay the circumstances behind the ergot poisoning theory for this historical event are described. When the evidence is weighed carefully both pro and con, it seems unlikely that ergotism explains much of what went on in colonial Salem.
Read Linnda Caporael's 1976 paper (in Science) and weigh the evidence for yourselves: Ergotism: the satan loosed in Salem?