It happened. It may be one of the most bizarre things in history, but it happened. In 1518, the people of Strasbourg, France “danced themselves to death” for no obvious reason One woman started it, and others joined her. Within a month, there were 400 people involved.
As the situation in Strasbourg got worse, the rulers of the land started to become concerned:
"[the people] sought the advice of local physicians, who ruled out astrological and supernatural causes, instead announcing that the plague was a ‘natural disease’ caused by ‘hot blood.’ However, instead of prescribing bleeding, authorities encouraged more dancing, in part by opening two guildhalls and a grain market, and even constructing a wooden stage. The authorities did this because they believed that the dancers would only recover if they danced continuously night and day. To increase the effectiveness of the cure, authorities even paid for musicians to keep the afflicted moving."
Now, according to John Waller, who wrote not one, but TWO books on the event, the outbreak was caused by mass psychogenic illness (MPI), a manifestation of mass hysteria that is often preceded by extreme levels of psychological distress. According to Waller, a famine, caused by cold winters, hot summers, crop frosts, and violent hailstorms. In addition to the wide-spread famine, smallpox, syphilis, and leprosy afflicted the populace, as well. Waller believes this series of events might have triggered the MPI.