Yes, the dancing plague of 1518 was a real historical event, and dancing mania, also known as dancing plague or choreomania, is a documented phenomenon that occurred in various parts of Europe during the medieval and early modern periods.
The most famous incident of the dancing plague occurred in the city of Strasbourg, Alsace (now part of France), in July 1518. During this event, a woman named Frau Troffea started dancing uncontrollably in the streets. Within a week, the number of dancers grew to around 400, and the frenzied dancing continued day and night for about a month. It led to exhaustion, injury, and, in some cases, death. The authorities at the time believed the condition was caused by a "hot blood" imbalance and attempted to address it through more dancing.
Dancing mania was not a singular occurrence, as similar outbreaks were reported in other regions and at different times in history. People affected by dancing mania often experienced an irresistible urge to dance, and the phenomenon was often associated with mass hysteria and psychological distress. While the exact cause of these outbreaks remains uncertain, various theories have been proposed, including mass psychogenic illness, stress, religious fervor, and social factors.
As for whether a dancing plague could happen today, it's highly unlikely to occur on the same scale as it did in the past. Our understanding of mental health and mass psychogenic illnesses has advanced significantly since the medieval period. Additionally, improved communication, medical knowledge, and awareness of psychological conditions would likely prevent such an event from reaching the same magnitude.
However, it's worth noting that mass psychogenic illnesses, where a group of people develops similar physical symptoms with no underlying medical cause, can still occur in modern times. These episodes are often triggered by stress, anxiety, or other psychological factors, but they typically don't involve dancing mania or the same level of uncontrollable physical behavior. When such events do happen, they are thoroughly investigated by medical professionals and public health authorities to rule out any organic causes.
In summary, the dancing plague of 1518 and dancing mania were real historical occurrences, but due to our understanding of psychology and advances in medical science, it's highly unlikely that a similar dancing plague would happen on a large scale in modern times.