The dance plague (or dance epidemic) of 1518 was, most likely, a case of mass hysteria that occurred in Strasbourg, Alsace (then part of the Holy Roman Empire) in July 1518. About 400 people began dancing for days, and, after roughly a month, some of them died of heart attack, stroke, or fatigue.
The phenomenon of the “dance plague” began in Strasbourg in July 1518, when a woman, Troffea, without any reason began to dance madly in the streets of the city. It was immediately evident that Troffea”s dance was not a real dance, but rather a sequence of uncoordinated and asynchronous movements, twists and turns. Her dance went on for a whole week, during which 100 people joined her. The city authorities, disoriented by the chaos caused by the phenomenon, gathered to deliberate on it, not without having consulted the city”s doctors: at first, however, in the belief that “this dance fever” would have died down after a few days, they thought it was a good idea to support her, and so they set up a wooden stage on which people could dance. Even experienced musicians and dancers were paid to give rhythm and choreography to the dancers.
Things, however, did not go as planned: after a few days, the weakest individuals began to die of exhaustion, while, at the same time, the number of people joining this frenzied dance grew, reaching 400 individuals at the end of August. At the beginning of September, faced with the spread of the phenomenon and, above all, the increase in deaths, the Strasbourg authorities decided to take drastic action: they forced all the people who had not yet stopped dancing to leave the city, pushing them towards the hills surrounding the city of Saverne. In the cave of one of these hills there was a sanctuary dedicated to San Vito, patron saint of dance: here the “dancers” were led around a wooden effigy of the saint, in a sort of exorcistic ritual. Then, they were hospitalized in Strasbourg, and, a few days later, they gradually stopped dancing, so that the epidemic disappeared as it had appeared, not without having made a presumably large number of victims, but it is not reported by the sources of the time.
The cause of all this was probably mass hysteria or something more mysterious; the authorities of the time thought that the dancers had ingested ergot, a cereal on the stalks of which grows a kind of mold with hallucinogenic effects that can cause real spasms and make it difficult for the flow of blood in the body, thus causing uncoordinated and strange movements. This is however a rather improbable hypothesis, because, in order to make 400 people dance for more than one month, it would have been necessary an immense quantity of ergot. It is therefore a real bizarre fact, but it was not the only outbreak of compulsive dancing in Europe: before the one in 1518, there were 10 other cases; in particular, one in 1374 involved many cities in what is now Belgium, northeastern France and Luxembourg.
Another interesting fact is that the documents of the time show that the people affected by this “epidemic” did not want to dance. All of this makes the hypothesis probable that it was a phenomenon of mass hysteria inaugurated by Troffea. For many countries of Northern Europe, 1518 was a critical year, marked by strong political tensions and by a famine for which the poor of Strasbourg returned to experience hunger: it is very likely that the sense of precariousness linked to political events and the desperation caused by hunger acted as a “stress factor”, unleashing in people a state of trance that led them, against their will, to dance themselves to death.