I have never heard of this bizarre and eerie occurrence before. At first glance, "The Dancing Plague" seems to share a resemblance with the trance-like convulsions made popular by certain religious sects. But accounts suggest such episodes of mass hysteria might be able to become widespread and even more malignant.
"In July of 1518, a woman referred to as Frau Troffea stepped into a narrow street in Strasbourg, France and began a fervent dancing vigil that lasted between four and six days. By the end of the week, 34 others had joined her and, within a month, the crowd of dancing, hopping and leaping individuals had swelled to 400.
Authorities prescribed "more dancing" to cure the tormented movers but, by summer's end, dozens in the Alsatian city had died of heart attacks, strokes and sheer exhaustion due to nonstop dancing."
It's as funny as it is frightening. But it gets worse.
At least seven other outbreaks of the dancing epidemic occurred in medieval Europe, mostly in the areas surrounding Strasbourg. In more recent history, a major outbreak occurred in Madagascar in the 1840's, according to medical reports that described "people dancing wildly, in a state of trance, convinced that they were possessed by spirits."
Perhaps the most unusual documented case of mass psychogenic illness was the Tanganyika Laughter Epidemic of 1962. A paper published the following year in the Central African Journal of Medicine described what happened.
Triggered by a joke among students at a Tanzania boarding school, young girls began to laugh uncontrollably. At first there were spurts of laughter, which extended to hours and then days.
The victims, virtually all female, suffered pain, fainting, respiratory problems, rashes and crying attacks, all related to the hysterical laughter. Proving the old adage that laughter can be contagious, the epidemic spread to the parents of the students as well as to other schools and surrounding villages.
Eighteen months passed before the laughter epidemic ended.
Since at least 300 B.C., plagues of koro -- an irrational male fear that one's genitals have been stolen or are fatally shrinking into the body -- have swept through various parts of the world, particularly throughout Africa and Asia. Most recently, a 1967 outbreak, documented in the Singapore Medical Journal, caused over 1,000 men to use pegs and clamps in hopes of protecting themselves from the gripping fear.
Luckily, it seems researchers are finally arriving at a reasonable explanatory model for these strange outbreaks of mental illness.