On the fourteenth of July 1518, a resident of Strasbourg by the name of Troffea left her half-timbered house onto a narrow crooked street of the city and, unexpectedly for everyone around her, began to dance. Without music or any reason, just a stupid dance that continued, despite her husband's pleas to change his mind, until the very night, when fatigue nevertheless won.
The next morning, the unusual performance continued, and Frau danced until she was exhausted, refusing to take breaks. An audience even formed around her, watching with pleasure other people's madness. Four days later, the burgomaster of the city got tired of all this, and he allegedly ordered to take the unfortunate woman to the neighboring town of Saverne, where the chapel of St. Vitus was located, supposedly healing in such situations. Whether Frau has recovered, history is silent.
Another thing is much more interesting - she has followers. A week after the beginning of all these events, at least 30 people were already dancing in the city, and their number grew and grew.
These are all not medieval inventions, but real historical events recorded in numerous sources, chroniclers' writings and even drawings by contemporaries. His description of the disease was also left by a Swiss doctor who came to Strasbourg a few years later, known under the pseudonym Paracelsus.
Such epidemics were common in medieval Europe. Most of these cases are localized on the modern Franco-German-Swiss borderlands. For no apparent reason, the inhabitants of this or that town suddenly began to dance, many of them - up to complete exhaustion, which ended in death.
In Strasbourg, the city authorities decided that music would heal the sick, set up a temporary stage and invited orchestras, but the situation only got worse - the number of dancers increased. The exact cause of the disease is still not known. Some talk about bacteria and viruses, some talk about mental disorders. The most famous theory is that it's all about the disputes of a mysterious mushroom.
We'll be glad to hear your theories in the comments.