OK, no towns were actually completely depopulated but the epidemic of English sweating sickness had a significant and devastating effect upon the communities it affected. The 1551 outbreak was centred around the town of Shrewsbury from where it spread, locally at first to Oswestry, Presteigne, and, a bit further, to Chester, eventually reaching London in after about three months. T the time of the outbreak, the population of Shrewsbury is thought to have been between 3,000 and 5,000. The sickness claimed 1,000 of those lives, with many more people fleeing the area. The town population fell significantly.

This pattern was to repeat throughout England.

English sweating sickness surfaced in 1485, in the weeks around Henry VII’s seizure of the English throne, and struck in a series of epidemics before disappearing for good after 1551. In between, it left a trail of sudden death and a puzzle that medicine has never solved.

Contemporaries described a horrifyingly rapid illness. A person could feel perfectly well at dinner and be dead by morning. The symptoms began with a sense of apprehension and dread, then cold shivers, aching limbs, headache and dizziness. This gave way to the phase that named the disease: a drenching, malodorous sweat, a pounding heart, breathlessness, and collapse. Survival or death was often decided within a single day. Those who lived through twenty-four hours generally recovered; many were dead before the day was out.

The sweat had odd characteristics that still baffle historians and epidemiologists. Unlike most epidemics of the era, it seemed to prefer the young, the fit, and the affluent — striking robust men in their prime rather than the old and frail. It ravaged England while largely sparing Scotland, Wales, and Ireland. And in its final major appearance in 1528, it leapt across the Channel to sweep through the German lands, Scandinavia, and the Low Countries, while curiously bypassing France and Italy almost entirely, before receding again.

Its reach touched the highest levels of Tudor society. Anne Boleyn is said to have caught and survived it in 1528, while others in Henry VIII’s circle were not so fortunate, and the king himself fled from residence to residence in fear of it. The last outbreak, in 1551, produced the one detailed medical account we have, from the physician John Caius, who set down its symptoms and course in a short treatise.

Then the sickness simply was gone.

There are many theories. Some researchers favour a hantavirus carried by rodents, pointing to the sudden respiratory collapse that hantaviruses can cause. Others have proposed a relapsing fever spread by ticks or lice, an unknown strain of influenza, or even a form of anthrax. The trouble is that no theory accounts for all the disease’s speed, social selectivity or its limited geography and, crucially, no physical trace survives.

From a modern view, the symptoms are consistent with sepsis, but what was the cause?

The sweating sickness therefore remains a genuine cold case: a lethal illness that shaped the anxieties of Tudor England, then slipped out of the historical record just before medicine developed the tools that might have caught it.

In July 1518, a woman remembered only as Frau Troffea stepped into a lane in Strasbourg and began to dance. There was no music, no festival, no evident reason — she just danced and would not stop. She danced through the day and into the night, when at last she dropped from exhaustion. After a brief rest she got up and started dancing again. Within days a handful of others had joined her. Within a month, according to the city’s chronicles, the compulsive dancers numbered in the hundreds.

Witnesses described faces contorted with distress, bodies slick with sweat, feet bloodied and bruised. Some of the dancers reportedly collapsed and died though the true death toll is impossible to verify from the surviving records.

The response of the authorities now appears naive. Strasbourg’s physicians, working from the medical theory of the day, concluded that the dancing arose from “hot blood” and that the only cure was to let the sufferers dance it out of their system. So the city cleared two guildhalls, roped in professional pipers and drummers, and even erected a wooden stage. Predictably, the intervention made everything worse: the spectacle drew in still more dancers, and the mania fed on itself.

What actually happened is still uncertain. One long-standing theory blames ergot, a psychoactive mould that grows on damp rye and can trigger convulsions and hallucinations. But ergot poisoning causes fits and tends to constrict blood flow to the limbs, causing pain and gangrene rather than sustained, coordinated dancing.

The explanation favoured by most historians today is mass psychogenic illness: a collective stress response in a population ground down by famine, disease, and the constant dread of divine judgement. Strasbourg in 1518 was perfect for this.

Locals also feared St. Vitus, a saint believed capable of cursing sinners with compulsive dancing, a belief that may have shaped the form of the affliction, the mind reaching for a template already lodged in the culture.

The episode is among the best-documented outbreaks of its kind, preserved in physician notes and municipal records. But it was not unique: similar dancing manias had rippled through the Rhine and Mosel regions for at least a century and a half, with a notable outbreak in 1374. But Strasbourg remains the most vivid and unsettling exapmle; a case study in how the mind, under sufficient pressure and given the right cultural background, can drive the body to lethal extremes we still cannot fully explain.