Weird History

The Dancing Plague of 1518

In Strasbourg, hundreds of people danced uncontrollably for weeks — some to their deaths. Nobody really knows why.

Why this rabbit hole matters

In July 1518 in Strasbourg (then part of the Holy Roman Empire), a woman named Frau Troffea began dancing in the street and could not stop. Within a month, around 400 people had joined her, dancing uncontrollably for days or weeks. Some reportedly died from exhaustion, heart attacks, or strokes. The authorities, following medical advice of the time, hired musicians and opened a dance hall to encourage the afflicted to dance it out of their systems. It remains one of history's most baffling medical mysteries.

The Dancing Plague (Tanzwut) of 1518 began in Strasbourg when Frau Troffea started dancing compulsively in mid-July and didn't stop for days. By August, roughly 400 people had been afflicted. Contemporary chronicles, physician notes, and city council records all confirm the event happened. The city hired musicians, believing dancing would resolve the crisis — which may have prolonged it. Modern explanations range from mass psychogenic illness (mass hysteria) to ergot poisoning to encephalitis lethargica, but no consensus exists.

Connections to follow

Mass Psychogenic Illness

Mass psychogenic illness (MPI), formerly called mass hysteria, occurs when groups of people develop similar symptoms — often motor or sensory — without a physical cause, triggered by anxiety, social contagion, and shared belief systems. Modern examples include the 2011 Le Roy, New York case where 12 teenage girls developed Tourette-like tics, the 'Havana Syndrome' in US embassy workers, and factory workers who collectively fainted after a perceived gas smell. MPI disproportionately affects people under extreme stress and spreads via social networks.

Ergotism

Ergotism is poisoning from ergot fungus (Claviceps purpurea), which infects rye and other grains. The convulsive form causes spasms, seizures, hallucinations, and involuntary movements that could superficially resemble compulsive dancing. Ergotism has been implicated in the Salem Witch Trials (historian Linnda Caporael's 1976 proposal), and may explain other medieval mass afflictions. However, ergot poisoning typically causes individuals to seize up, not dance coherently for weeks — and the social spread pattern of the 1518 plague better matches psychogenic illness.

Tarantism

Tarantism was a condition, prevalent in southern Italy from the 15th to 17th centuries, in which people believed they had been bitten by the tarantula spider and could only be cured by frenzied dancing to specific music — the tarantella. The afflicted (tarantati) would dance for days, often in a trance, and the condition recurred annually. Modern scholars believe tarantism was a culturally sanctioned form of psychological catharsis, possibly related to suppressed grief or trauma — particularly among women who had limited other outlets.

Medieval Medicine

Medieval medicine was a synthesis of Galenic humoral theory (four humors: blood, phlegm, yellow bile, black bile), Aristotelian natural philosophy, Islamic scholarship, and Christian theology. Disease was understood as imbalance of humors or divine punishment. For the Dancing Plague, Strasbourg physicians attributed the affliction to 'hot blood' and recommended more dancing to purge it — which is why the city opened a dance hall. Understanding medieval medicine illuminates why historical responses to outbreaks so often made them worse.

The Strasbourg Context: Why 1518 Was a Year of Desperate Crisis

The dancing plague did not erupt in prosperous, stable Strasbourg. The summer of 1518 followed years of famine, plague, smallpox, and syphilis epidemics across the Upper Rhine region. The winter of 1517-18 had been severe; harvests were poor; grain prices were high. Religious anxieties ran parallel — Martin Luther posted his 95 Theses in October 1517, triggering a theological crisis that would engulf the region. The Reformation's challenge to Church authority created profound uncertainty about salvation, punishment, and divine will. Many local people believed they were being punished by Saint Vitus — a folk belief so established that contemporary physicians actually recommended dancing as a cure. The crisis context is not incidental to the dancing plague; it may be its primary cause.

Other Mass Psychogenic Illnesses in History

Mass psychogenic illness (MPI) has been documented in virtually every century, and the pattern is consistent: it occurs in high-stress closed communities, spreads through social transmission, and resolves when the community context changes. Notable episodes include: the Halifax Slasher hoax of 1938 (multiple residents fabricated knife attack wounds until the fraud collapsed); the June Bug Epidemic of 1962 (62 textile workers in a US factory developed rashes and fainting after believing an insect in the fabric was causing illness — no insect was ever found); the Le Roy, New York episode of 2011-12 (18 girls developed Tourette-like tics traced to anxiety in a tight-knit school community). MPI is now a recognized and studied phenomenon, not a historical curiosity.