In July 1518, in the city of Strasbourg, a woman known to history as Frau Troffea stepped into the street and began to dance. There was no music and no festival. She simply danced, for hours, until she dropped from exhaustion, and then she got up and danced again. Within a week dozens of her neighbours had joined her. Within a month, by some accounts, as many as four hundred people were dancing in the streets and could not make themselves stop.
This is not a legend dressed up as history. The dancing plague of 1518 appears in physicians’ notes, cathedral sermons and the city’s own council records, which describe the authorities arguing over what to do with a crowd that would not stand still.
Their solution made things worse. Convinced the afflicted needed to dance the sickness out of their bodies, the city guilds cleared halls, hired musicians and even built a wooden stage, urging the dancers to keep going until the fit passed. It did not pass. People reportedly collapsed from strokes and sheer exhaustion. How many died is genuinely uncertain: later chronicles claim as many as fifteen a day at the peak, but Strasbourg’s surviving records never settle on a firm number, and some historians doubt anyone died at all.
So what was it? The most careful modern account comes from the historian John Waller, who reads the episode as a case of mass psychogenic illness, the same mechanism behind fainting outbreaks that still sweep through schools and factories today. Strasbourg in 1518 was a city on its knees, hammered by famine, disease and a local belief that a saint named Vitus could curse sinners with a compulsion to dance. Put enough terrified, starving, deeply superstitious people together, Waller argues, and one woman’s breakdown can spread through a crowd like a spark through dry grass.
Other researchers have floated ergot, a hallucinogenic mould that grows on damp rye and can cause convulsions. The trouble is that ergot poisoning tends to choke off blood flow to the limbs, which is close to the opposite of what you need to dance for days. Five centuries on, the safest thing to say is that a whole town lost control of its own bodies, wrote it all down, and still left us guessing.
