"And, in fact, one 13th Century outbreak – a literal form of dance fever – occurred south of Hamelin, in the town of Erfurt, where a group of youths were documented as wildly gyrating as they travelled out of town, ending up 20km away in a neighbouring town. Some of the children, one chronicle suggests, expired shortly thereafter, having flat-out danced themselves to death, and those who survived were left with chronic tremors. Perhaps, some theorise, Hamelin witnessed a similar plague, dancing to the figurative tune of the Piper."

Early discovery of MDMA.

Could have been ergot fungus in the wheat