The Dancing Plague of 1518

On 14 July 1518, a woman named Frau Troffea stepped into a narrow cobbled street in Strasbourg, in what is now eastern France, and began to dance.

There was no music. No occasion. She simply began to move, alone, outside her half-timbered house. She kept dancing for a week, pausing only to sleep. Her husband joined her. Then their neighbours. Within days, thirty people were dancing. By August, somewhere between fifty and four hundred people were in motion, and they could not stop.

Their movements were spasmatic, convulsive. Arms thrashed. Eyes went vacant and expressionless. Blood pooled in their swollen feet, seeping into their shoes. If they did not die of a heart attack, they collapsed from exhaustion, hunger, and thirst. Contemporary accounts claim as many as fifteen deaths per day at the outbreak's peak (though the city's own records never mention fatalities, and the dispute over the death toll continues).

The cure that made it worse

The Strasbourg city council did what medieval authorities did when faced with the inexplicable: they called in physicians. The doctors examined the dancers, consulted their texts, and delivered their considered professional opinion: the afflicted should dance themselves free of it.

The council refurbished guild halls for dancing. They hired musicians. They stationed strong men beside the dancers to keep them upright. If the disease was too little dancing, then more dancing was the cure.

It didn't work. It made everything worse.

More dancers joined. The city banned public dancing. Then they banned music. Nothing helped. The dancers now believed they were being punished by Saint Vitus, the patron saint of dancers, whose curse compelled his victims to dance until they dropped. To be "free of sin," people who had not been dancing began to join in.

The red shoes

It is one of the great bureaucratic ironies of history: the city council, by trying to manage the crisis, amplified it. Their physician-approved intervention — more dancing, more music, more space — turned a localised outbreak into a regional epidemic. The cure was indistinguishable from the disease.

What caused it?

Two main theories:

Ergotism. The ergot fungus grows on rye and produces ergotamine, a psychoactive compound structurally related to LSD — in fact, LSD was first synthesised from ergotamine. Ergot poisoning causes hallucinations, convulsions, and twitching. The same fungus has been implicated in the Salem witch trials. But John Waller, the leading modern researcher on the dancing plague, argues that ergotism can't explain why victims danced for days without stopping, why so many reacted identically, or why every outbreak clustered along the Rhine and Moselle rivers — areas linked by water but with different climates and crops.

Mass psychogenic illness. Waller's own theory. The people of Alsace in 1518 were living through brutal years even by early modern standards: famine, disease, crushing poverty. Waller proposes that the dancing was a form of stress-induced mass hysteria — a collective trance state in which a shared belief (Saint Vitus's curse) manifested as identical physical symptoms. Seven other dancing plagues were recorded in the same region during the medieval period. They all look the same: a single trigger, social contagion, and a community that believed dancing was a punishment from God.

The ergot vs. hysteria debate is unresolved, but Waller's argument has one uncomfortable piece of evidence behind it: the city council's intervention worked as mass hysteria theory predicts. Giving the dancers a sanctioned space, music, and an audience multiplied their numbers. Banning everything public pushed them toward the one sanctioned outlet — the shrine — and it stopped.

If the cause was a fungus, the council's actions shouldn't have changed anything. If the cause was belief, their actions were the whole story.