The Sweating Sickness (1485–1551).
It came on without warning — a sudden dread, then shivering, then a drenching, fatal sweat — and it could carry off a healthy man between the morning and the evening of a single day. The English sweating sickness terrorized Tudor England five times across two-thirds of a century, killing rich and poor, sparing the plague's usual logic, and emptying towns in panic. Then, after 1551, it simply stopped, and never came again. Nearly five hundred years later, with all the tools of modern medicine, we still cannot say for certain what it was.
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What the sweating sickness was, in a paragraph.
The sweating sickness (Latin sudor anglicus, “the English sweat”) was a mysterious and often rapidly fatal epidemic disease that struck England in five distinct outbreaks — in 1485, 1508, 1517, 1528–29, and 1551 — and then disappeared entirely. The first outbreak arrived in 1485, around the time of Henry VII's accession after the Battle of Bosworth, and the disease became a recurring terror of the Tudor age. Its hallmark was a sudden onset and extraordinary speed: victims experienced a sense of apprehension and cold shivers, followed by high fever, severe headache and body aches, exhaustion, and then a profuse, drenching sweat, with many sufferers dying within hours of the first symptoms — sometimes between morning and night of the same day. Those who survived the first day often recovered. The disease had several puzzling epidemiological features that distinguished it sharply from the more familiar bubonic plague: it tended to strike in summer and early autumn; it disproportionately affected the well-off, the young, and the robust (including the wealthy and the gentry) rather than the poorest; it spread quickly through a town and then moved on; and the 1528–29 outbreak notably spread to continental Europe (Germany and beyond) before receding, whereas other outbreaks were largely confined to England. After the 1551 epidemic — documented by the physician John Caius, who wrote the principal contemporary medical account — the sweating sickness never returned. The cause has never been established and remains genuinely unidentified. The leading modern hypothesis is that it was caused by a hantavirus (a family of rodent-borne viruses, some of which cause a rapidly fatal cardiopulmonary syndrome with features resembling the sweat), which would fit the seasonality, the rural/robust victim profile, and the lack of clear person-to-person spread in the modern sense; however, this is unproven and debated, partly because hantaviruses are not generally thought to transmit between people the way the sweat seemed to. Other proposed causes include relapsing fever (a tick- or louse-borne bacterial infection), an unknown or now-extinct viral pathogen, influenza variants, or other agents — none confirmed. Because no biological samples survive and the historical descriptions, while detailed for their time, cannot pin down a pathogen, the question may never be fully resolved unless ancient-DNA evidence is recovered from remains. The sweating sickness is therefore a real, well-documented historical disease whose identity is a genuine open medical mystery: an epidemic that killed thousands, shaped Tudor life, and then vanished, leaving behind vivid accounts of its terror but no certain name. It stands as a reminder that even comparatively recent, literate societies could be visited by a deadly disease that modern science still cannot confidently identify.
The documented record.
The outbreaks
Five epidemics are documented. Verified The sweating sickness struck England in 1485, 1508, 1517, 1528–29 (spreading to Europe), and 1551, then disappeared after 1551 [1][2].
The symptoms and speed
It killed with notorious rapidity. Verified Onset was sudden — apprehension, shivering, fever, aches, exhaustion, and a profuse sweat — with death often within hours; survivors of the first day usually recovered [1][2].
The unusual epidemiology
It differed from plague. Verified The disease favored summer, struck the robust and well-off, and behaved differently from bubonic plague — features documented by contemporaries including John Caius (1552) [1][3].
The cause is unidentified
No pathogen has been confirmed. Verified Despite hypotheses, the causative agent of the sweating sickness has never been identified, and no biological samples are known to survive [2][3].
The competing positions.
The leading modern hypothesis is that the sweat was a hantavirus infection, fitting its seasonality and victim profile. Claimed Alternatives include relapsing fever, an unknown/extinct virus, or influenza variants; each explains some features but not all [2][3].
This archive treats the sweating sickness as a real disease of unidentified cause, regards the hantavirus hypothesis as the strongest current candidate while emphasizing it is unproven (notably the puzzle of apparent person-to-person spread), and notes that a definitive answer likely awaits ancient-DNA evidence from period remains. Disputed The genuine mystery is the pathogen's identity and why the disease appeared and then vanished, not whether the epidemics were real [1][3].
The unanswered questions.
The pathogen
Its identity is unknown. Unverified No agent has been confirmed; competing hypotheses each leave features unexplained [2][3].
Why it appeared and vanished
The emergence and disappearance are unexplained. Disputed Why the disease arose in 1485 and ceased after 1551 — whether through pathogen evolution, ecological change, or other factors — is not understood [1][2].
The mode of spread
Its transmission is uncertain. Disputed Whether it spread person-to-person or via a vector/reservoir (as hantavirus would imply) is unresolved and central to identifying it [3].
Primary material.
The accessible record on the sweating sickness is held principally in these sources:
- John Caius, A Boke or Counseill Against the Disease Commonly Called the Sweate (1552) — the key contemporary medical account.
- Tudor chronicles and town records documenting the outbreaks and mortality.
- Continental accounts of the 1528–29 spread (the “English sweat” in Germany).
- Modern epidemiological and historical-medicine analyses (hantavirus and other hypotheses).
- Any future ancient-DNA studies of period remains.
Critical individual sources include: Caius's treatise; the chronicle record; and modern pathogen analyses.
The sequence.
- 1485 The first outbreak strikes England around Henry VII's accession.
- 1508, 1517 Further epidemics recur.
- 1528–29 A major outbreak spreads to continental Europe.
- 1551 The last epidemic; John Caius writes the principal medical account (1552).
- After 1551 The sweating sickness never returns; its cause remains unidentified.
Cases on this archive that connect.
The Dancing Plague of 1518 — another bizarre, contemporaneous epidemic phenomenon.
The Plague of Athens (File 287) — another deadly epidemic whose pathogen is unidentified.
The Black Death Origin Debate (File 286) — an epidemic whose pathogen, by contrast, has now been identified.
The Year Without a Summer (File 239) — another historical catastrophe reconstructed after the fact.
More related files coming as the archive grows. Planned: historical epidemics and the limits of retrospective diagnosis.
Full bibliography.
- John Caius, A Boke or Counseill Against the Disease Commonly Called the Sweate (1552).
- Tudor chronicles and town records documenting the 1485–1551 outbreaks.
- Continental accounts of the 1528–29 “English sweat” in Europe.
- Modern historical-medicine analyses, including the hantavirus and relapsing-fever hypotheses.