In July 1518, in the city of Strasbourg — then part of the Holy Roman Empire — a woman known to history as Frau Troffea stepped into the street and began to dance. There was no music. She danced through the day, into the night, and was still going days later, feet bloodied, apparently unable to stop.
Then others joined her. Within a week, around three dozen people were dancing. Within a month, chroniclers put the number as high as 400 — a city’s worth of people jerking and hopping in the summer heat, many begging for help even as their bodies kept moving. Contemporary accounts describe dancers collapsing from exhaustion, and some sources report deaths from strokes and heart attacks, though the exact toll is one of many contested details.
The worst public-health response imaginable
Strasbourg’s authorities consulted physicians, who ruled out astrological and supernatural causes and diagnosed “hot blood.” The prescribed cure: the afflicted should simply dance it out. The council duly opened guildhalls for dancing, erected a stage, and — in the decision that secures the episode’s place in history — hired musicians to keep everyone moving.
Predictably, public music and spectacle recruited more dancers. Only when the scale of the disaster became undeniable did the city reverse course, banning music and dancing outright and eventually carting the afflicted to a shrine of St Vitus — the saint associated with dancing afflictions — where the epidemic gradually burned itself out by early autumn.
Ergot, or something sadder
The tidy modern explanation — ergot, the LSD-related fungus that grows on damp rye — largely falls apart on inspection: ergot poisoning constricts blood flow and causes convulsions, not days of sustained, coordinated dancing. The explanation most historians now favour, argued in detail by John Waller, is mass psychogenic illness: a stress-induced trance state sweeping through a population primed to believe it possible. And 1518 Strasbourg was primed — ruinous harvests, new diseases, and a deep local belief that St Vitus could curse sinners with compulsive dance. People who fully believed a dancing curse existed, under unbearable stress, began to manifest it; each new dancer made the curse more real for the next.
Similar outbreaks dot the medieval record along the Rhine and Moselle, and psychogenic epidemics still occur today — spread now by screens rather than streets. The Strasbourg episode endures because its records are so vivid and its lesson so uncomfortable: belief, under enough pressure, is a physical force.
