The dancing plague of 1518 was a weird dancing obsession in Strasbourg, Alsace (modern-day France), in the Roman Empire in July 1518. Somewhere between 74 and 380, people took to dancing for days.
The dancing outbreak occurred in July 1518 when a girl started dancing fervently in the street in Strasbourg.
Historical documents, including cathedral sermons, physician notes, regional and local chronicles, and even notes published by the Strasbourg town council, are clear that the victims danced. The reason is still unknown.
Archival sources agree that there was a dancing outbreak after a lady started dancing, a bunch of mostly young ladies joined in, and the constant dancing did not seem to die down for days. It continued for such a long time that it pulled the Strasbourg bishop and magistrate’s attention, and some number of doctors eventually intervened, putting the distressed in a hospital.
Possible reasons behind the dancing plague:
Stress-induced mass hysteria
Modern scientists believe that this could have been a flamboyant example of psychogenic movement disorder in mass hysteria, which involves many individuals suddenly displaying the same unusual behavior. The behavior spreads broadly and rapidly in an epidemic pattern. This type of bizarreness could have been generated by high psychological stress levels caused by the brutal late medieval years. Starvation and mental illness could have triggered this epidemic. This psychogenic illness caused by starvation could have created chorea (meaning “to dance”), a situation involving irregular and complex, erratic movements that flit from body part to body part. Diverse choreas (St. John’s dance, St. Vitus’ dance, tarantism) were recognized in the Middle Ages, referring to the epidemics of dancing obsession in Europe, especially at the time of the plague.
Other researchers believe that the dancing could have been carried on by food poisoning caused by the psychoactive and toxic ergot fungi products, which generally grow on grains (such as rye) used for preparing bread. Ergotamine is the primary psychoactive product of ergot fungi; it is structurally linked to the drug LSD-25 (lysergic acid diethylamide) and is the basis from which LSD-25 was initially synthesized. The same fungus has also been involved in other significant historical anomalies, including the Salem witch trials. However, ergot alone would not cause hallucinations or unusual behavior except when mixed with opiates.
Some references maintain that, for a duration, the plague killed around sixteen people daily. However, the sources of Strasbourg’s town at the days of the events did not specify the number of deaths or even if there were casualties. There do not appear to be any sources contemporary to the events that make a note of any life losses.