Dancing Plague?

Did you know there was a dancing plague? 

On June 24th, 1374 in Aachen, Germany an outbreak began of the dancing plague or dancing mania also known as St. Vitus' dance.   From Aachen it spread across central Europe and as far away as England and Madagascar. Dancing mania affected groups of people — as many as thousands at a time — and caused them to dance uncontrollably for days, weeks, and even months until they collapsed from exhaustion. Some danced themselves to death, suffering heart attacks or broken hips and ribs. At the time, people believed the plague was the result of a curse from St. Vitus. Scientists now tend to believe it was due to ergot poisoning or mass hysteria.  ~ The Writer's Almanac