In July 1518, a woman known as Frau Troffea suddenly began dancing in the streets of Strasbourg. There was no music. There was no joy on her face. She simply danced — for hours, then for days.
Within a week, dozens had joined her. Within a month, records describe hundreds of people caught in the same uncontrollable dance. Documents from the era tell of dancers with bleeding feet, people collapsing unconscious, and some dying of heart attacks, strokes, or pure exhaustion.
The city’s response only made things worse. Physicians concluded the problem was “overheated blood,” and prescribed a cure: more dancing. The city built public stages and even hired musicians. The result was a disaster — the plague grew.
So what actually happened to these people?
Over the centuries, many theories emerged. For a long time, blame fell on ergot — a fungus that grows on rye bread and produces effects similar to LSD. But that theory can’t answer a crucial question: ergot poisoning destroys muscle control, making days of continuous dancing nearly impossible.
Today, most historians support a different explanation: mass psychogenic illness — in other words, collective hysteria. In 1518, the people of Strasbourg were living through famine, disease, and intense religious fear. The region held a widespread belief in Saint Vitus, a saint said to punish sinners with a curse of dancing. In a society under extreme stress, a trance state triggered by that belief may have spread from person to person like a contagion.
The plague ended as mysteriously as it began, fading away in September. The dancers were taken to a mountain shrine and gradually recovered.
More than 500 years later, the Dancing Plague of 1518 remains one of history’s most striking proofs of how fragile the human mind can be in the face of collective fear and belief.
