Analysis of information sources in references of the Wikipedia article "Epidemia de baile de 1518" in Spanish language version.
Chronicles of 1374 tell of large numbers of men and women dancing, while screeching with pain, leaping into the air, running wildly from place to place, and calling on the mercy of God and the saints. [...] The 1374 outbreak occurred just after a devastating flood.
During another outbreak in 1518, the inhabitants of Strasbourg were reeling from severe famine, their morale already shattered by syphilis, smallpox and plague. They danced in their misery because people living along the Rhine and Moselle rivers had a longstanding fear of devils and saints who inflicted a terrible, compulsive dance. Having fallen into a trance state, they acted in accordance with these supernaturalist beliefs: dancing wildly for days on end.
