The Dancing Plague (or Dance Epidemic) of 1518 was a case of dancing mania that occurred in Strasbourg, Alsace (then part of the Holy Roman Empire) in July 1518. Numerous people took to dancing for days without rest, and, over the period of about one month, some of those affected died of heart attack, stroke, or exhaustion.
The outbreak began when a woman, Frau Troffea, began to dance fervently in a street in Strasbourg. This lasted somewhere between four to six days. Within a week, 34 others had joined, and within a month, there were around 400 dancers. Some of these people eventually died from heart attack, stroke, or exhaustion. Historical documents, including “physician notes, cathedral sermons, local and regional chronicles, and even notes issued by the Strasbourg city council” are clear that the victims danced. It is not known why these people danced to their deaths.