→ https://www.theguardian.com/stage/2018/jul/05/bizarre-dance-epidemic-of-summer-1518-strasbourg
→ https://en.wikipedia.org/wiki/Dancing_plague_of_1518
It started with just a few people dancing outdoors in the summer heat. Arms flailing, bodies swaying and clothes soaked with sweat, they danced through the night and into the next day. Seldom stopping to eat or drink, and seemingly oblivious to mounting fatigue and the pain of bruised feet, they were still going days later. By the time the authorities intervened, hundreds more were dancing in the same frenetic fashion.
But this was not one of those 80s raves that began in a remote layby and ended in a muddy field. Rather, it's one of the oddest epidemics to be recorded in world history.
→ https://en.wikipedia.org/wiki/Dancing_plague_of_1518
The outbreak began in July 1518 when a woman, Mrs. Troffea, began to dance fervently in a street in Strasbourg. This lasted somewhere between four and six days. Within a week, 34 others had joined, and within a month, there were around 400 dancers, predominantly female. Some of these people would die from heart attacks, strokes, or exhaustion. One report indicates that for a period, the plague killed around fifteen people per day.