What Caused the Dancing Plague of 1518?

Vol. I · Entry 22 · Plagues of the Mind

In July 1518 a woman began dancing in a Strasbourg street and did not stop. Within a week roughly thirty others had joined her; within a month, by the chronicles' count, several hundred. It went on into September. The best-supported explanation is mass psychogenic illness in a population under extreme stress, in a city where everybody already believed a saint could inflict compulsive dancing as a punishment.

The dancing is not the strangest part of this. The response is.

What the city did

Faced with citizens dancing themselves into collapse, the magistrates of Strasbourg consulted physicians. The physicians rejected demonic possession and astrological cause, and diagnosed hot blood — an imbalance of the humours. The prescribed treatment for hot blood was to work it out of the body.

So the council cleared two guildhalls and the grain market, had wooden stages built, and hired musicians to keep the afflicted moving until the affliction burned itself out.

That is in the council minutes. It is one of the strangest documented acts of public policy in European history, and it was arrived at rationally, by the medical consensus of the day, applied in good faith.

It made things worse. More people joined. By late summer the authorities reversed course entirely, banned music and public dancing, and began carting the afflicted to a shrine of Saint Vitus in the hills above Saverne, where they were given red shoes and led around a wooden figure of the saint.

The ergot theory, and why it fails

The explanation most people have heard is ergot poisoning — Claviceps purpurea, a fungus that grows on damp rye and produces alkaloids related to LSD. Rye was the bread grain of the Rhine. The harvests before 1518 were wet.

It does not work, for two reasons.

Ergotism produces convulsions, hallucinations, burning limb pain and gangrene — not sustained, coordinated, days-long dancing. Its victims cannot stand, let alone keep time. And ergot poisoning strikes whoever eats the bread: households, not individuals scattered across a city over weeks, with people joining and recovering at different times.

The pattern in the records is social contagion, not a shared meal.

What the conditions were

Strasbourg in 1518 was not a comfortable place. The preceding years brought failed harvests, grain prices the poor could not meet, and waves of disease — plague, smallpox, and the new pox, syphilis, which had arrived in Europe within living memory and was terrifying.

Into that, a specific belief. Saint Vitus was held to punish those who angered him by sending a compulsion to dance. This was not folklore at the margins; it was current, widely held, and a chapel to the saint stood a day's walk away.

The historian John Waller's argument is that these two things together are sufficient: a population in prolonged distress, plus an available and believed template for how distress expresses itself. Under enough strain, some people entered a trance state; because everyone knew what dancing sickness looked like, others followed. The council's stages and musicians did not just fail to help — by making the dancing visible and sanctioned, they gave the template a public performance.

Where the record goes silent

The death toll is not established. A widely repeated figure has fifteen people a day dying of stroke, heart attack and exhaustion at the peak. It comes from a single later chronicle and is not corroborated by the contemporary municipal record. People may well have died. The number should not be quoted as though it were counted.

The first dancer's name is thin. She is given as Frau Troffea in some accounts and appears unnamed in others. The detail that she danced alone for days before anyone joined is chronicle material, written after the fact.

Nobody recorded how it ended. The outbreak subsides from the record in September. Whether the shrine worked, or the weather changed, or the thing simply exhausted itself, the documents do not say.

What is certain is narrow and strange: several hundred people in a Rhineland city danced until they collapsed, and the government of that city, acting on the best medical advice available, built them somewhere to do it.

Sources

• Strasbourg municipal council minutes and city chronicles, 1518.
• Waller, J., A Time to Dance, a Time to Die: The Extraordinary Story of the Dancing Plague of 1518, 2008.
• Paracelsus, Opus Paramirum and related writings on the Strasbourg outbreak, composed during a visit to the city roughly a decade later.
• Contemporary physicians' notes and cathedral sermons preserved in the Strasbourg archives.