July 1518, in a part of the Holy Roman Empire called Stasbourg, France the Dancing Plague outbroke when a woman, Frau Troffea started fervently dancing in the streets. If one person fervently dancing wasn't odd enough within the week the number grew to fourteen people, in a months time... 400 people dancing. Some of these dancer died from a heart attack, from a stroke, or exhaustion. The local physicians ruled out supernatural or astrological causes but thought the dancing disease was caused by "hot blood" and that is was natural. Rather than the usual prescription of bleeding they encouraged more dancing. They encouraged my dancing by guiding them to a grain market, open two guidehalls, construct a stage, and even hire musicians to keep them dancing. This dancing mania was recorded in historical documents such as physician notes, cathedral sermons, local and regional chronicles, and the Stasbourg city council.
A
possible reason for such an odd plague is stress induced psychosis.
Some think the stresses around them, famine, disease, etc. was so
intolerable that it could cause mass psychological illness. This dancing
plague, or choreomania occurred on multiple occasions, the earliest
known incident in 1020 and most recently in the 1840s.