Dancing Plague of 1518 
"The Dancing Plague of 1518 was a case of dancing mania that occurred in Strasbourg, Alsace, France (then part of the Holy Roman Empire) in July 1518. Numerous people took to dancing for days without rest, and over the period of about one month, most of the people died from heart attack, stroke, or exhaustion."
http://en.wikipedia.org/wiki/Dancing_Plague_of_1518
"The Dancing Plague of 1518 was a case of dancing mania that occurred in Strasbourg, Alsace, France (then part of the Holy Roman Empire) in July 1518. Numerous people took to dancing for days without rest, and over the period of about one month, most of the people died from heart attack, stroke, or exhaustion."
http://en.wikipedia.org/wiki/Dancing_Plague_of_1518
