The dancing plague

 The dancing plague

or choreomania, also known as St . Vitus's dance was a weird medieval phenomenon from central Europe.

It involved spontaneous and continuous dancing by crowds of people until they collapsed or, worse, died.

In June 1374, one of the widest outbreaks began in Aachen, Germany, before spreading later to Colognes, Flanders, Utrecht, or Italy

There were still outbreaks more than a century later. In Strassburg, in july 1518, a woman named Frau Troffea began dancing in the street. Within four days, 33 others had joined her, and within a month, they were 400 ,many of whom suffered heart attacks and died.

At the time, some people believed the dancing was a curse brought about by St Vitus , who was a saint from Sicily , so they responded by praying and making pilgrimage to places dedicated to Vitus

Because no autopsy was carried out, only guess can be made as to the causes . It might have been some muscular or neurological inflammation leading to spasms, but who knows.

Source- Jem Duducu, Forgotten history.