...for a great YA historical novel (or bad poem).
Via BoingBoing, an article in the July 2009 issue of The Psychologist on "dancing plagues" (and other forms of mass hysteria):
The year was 1374. In dozens of medieval towns scattered along the valley of the River Rhine hundreds of people were seized by an agonising compulsion to dance. Scarcely pausing to rest or eat, they danced for hours or even days in succession. They were victims of one of the strangest afflictions in Western history. Within weeks the mania had engulfed large areas of north-eastern France and the Netherlands, and only after several months did the epidemic subside. In the following century there were only a few isolated outbreaks of compulsive dancing. Then it reappeared, explosively, in the city of Strasbourg in 1518. Chronicles indicate that it then consumed about 400 men, women and children, causing dozens of deaths…
[click to read more of "Looking Back: Dancing Plagues and Mass Hysteria" by John Waller]