History of Ergotism

As the dancing plague worsened, concerned nobles sought the advice of local physicians, who ruled out astrological and supernatural causes, instead announcing that the plague was a "natural disease" caused by "hot blood." However, instead of prescribing bleeding, authorities encouraged more dancing, in part by opening two guildhalls and a grain market, and even constructing a wooden stage. The authorities did this because they believed that the dancers would only recover if they danced continuously night and day. To increase the effectiveness of the cure, authorities even paid for musicians to keep the afflicted moving. Some of the dancers were taken to a shrine, where they sought a cure for their affliction.

As strange as it sounds, this "Dancing Mania" - also called choreomania, St. John's Dance and St. Vitus' Dance - was not uncommon in mainland Europe between the 14th and 17th centuries. One of the first outbreaks was in Aachen, Germany in 1374 and quickly spread throughout Europe until the highly documented case in Strasbourg in 1518.

One of the most prominent theories is that victims suffered from ergot poisoning, known as St Anthony's Fire in the Middle Ages - a psychedelic fungus that grows on grain (note there was a grain market in Strasbourg).* During floods and damp periods, ergot fungus was able to grow and affect wheat, rye and other crops which were used in making bread for the town folk.

From my perspective, the interesting thing about this story is it illustrates how people might have accidentally discovered psychotropic substances and then began to use them purposely in religious ceremonies. As mentioned in an earlier post on this subject, a number of Jewish and Christian cults in the Middle Ages are known to have used ergot in their communion to invoke religious ecstasy and the strange occurrences leading up to the Salem witch trials in America may have been ergotism (see link in comments).

As a side note, some suggest that the mysterious Tourette's-like epidemic that affected 21 people, mostly teenage girls from a small high school in rural upstate New York a few years ago, may have been ergotism. No causal link to ergot has been established in this case, but ergot symptoms do include convulsions that might be mistaken for both Tourette's and the Dancing Plague.

* LSD is distilled from the ergot fungus.