For years, the Mütter Museum invited visitors through its doors for a Halloween party that emphasized blood and guts. That event, Mischief at the Mütter, was scrapped amid the institute’s two-year ethical review. 

But the museum has come up with a new party theme for 2025, inspired by an alarming bit of medieval history.

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The revamped Halloween bash is called Choreomania, after an odd and largely unexplained phenomenon that emerged in the Middle Ages. Also called dancing plagues, the incidents involved groups of people dancing for days or weeks – stopping only when they collapsed from exhaustion or, per some reports, died.

Historians believe at least some of the tales were embellished. But infamous cases like the Dancing Plague of 1518 that tormented residents of Strasbourg, France, for two months were memorialized in municipal orders, sermons and physician accounts. Those afflicted with choreomania supposedly danced erratically and involuntarily, twitching in pain and screaming for help. Some described visions, leading scholars to theorize they were hallucinating.

Numerous theories have emerged in the centuries since the dancing plagues ended, roughly around the 1600s. Early explanations tended to center on religion, casting the plagues as punishment sent from God.

Modern authors, by contrast, have turned to biology and psychology. Some believe the medieval dancers ingested ergot, a fungus that grows on rye crop and induces hallucinations and spasms. Tarantula bites are another theory. Historian John Waller argued in several publications and a 2008 book that the dancing bouts were the result of mass psychogenic illness, spurred by stressors such as drought, leprosy and new ailments like syphilis.

Researchers now say it’s likely that multiple factors, not one singular cause, were behind the strange incidents.

The Mütter Museum’s version of Choreoman will take place inside Mitchell Hall, and “peasant core” costumes are encouraged.

Choreomania at the Mütter Museum

Thursday, Oct. 30 from 7-11 p.m
Tickets: $60
19 S. 22nd St., Philadelphia

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