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Strangest mass-hysteria events in history

History is dotted with instances of mass hysteria, a perplexing phenomenon in which large groups of people are struck by the same physical or mental affliction without any apparent explanation, from uncontrollable movement to widespread paranoia. Given the uncertainty as to what causes these curious events, contemporary doctors have remained baffled as to how to prevent or cure them. Though there are some theories, plenty of questions remain, in some cases hundreds of years after the incident took place. Let’s take a closer look at some of history’s strangest instances of mass hysteria, from the Middle Ages to the 20th century

Dancing plague of 1518

In 1518, the city of Strasbourg (in modern France) was overcome by a mysterious “dancing plague” that affected some 400 residents. It all began in July of that year, when a woman known as Frau Troffea began spontaneously dancing in the middle of the street. After a week of boogying solo, Troffea was joined by several dozen others who also developed the sudden urge to dance. The group only grew larger throughout the rest of the summer, expanding to several hundred people who danced until they collapsed from exhaustion, or in rare instances, suffered a fatal heart attack. Much as the event began without any explanation, the dancing epidemic a inexplicably started to wane by September, and the city returned to a state of normalcy.

Physicians at the time attributed the dancing ailment to “hot blood,” saying the only cure was for people to dance it out of their system until they no longer felt the urge. Other townsfolk believed they had been cursed by St. Vitus, the patron saint of dance, and were doomed to dance for eternity. But looking back, modern historians have several theories as to what caused the unusual event. Some believe it was induced by a combination of general stress and the side effects of new, untreated diseases such as syphilis. Another theory points to a fungus known as ergot, which is found on bread. If consumed, ergot can manifest itself in victims as spontaneous convulsions that may look like dance moves.

Salem witch trials

Between February 1692 and May 1693, more than 200 innocent people were accused of practicing witchcraft in the colonial town of Salem, Massachusetts. These accusations gave way to a mass hysterical event known today as the Salem Witch Trials, which was caused by a combination of xenophobia, religious extremism, and sexism. 

The paranoia began at the house of Puritan minister Samuel Parris, whose 9-year-old daughter, Betty, along with her 11-year-old cousin, Abigail, began making unintelligible noises and convulsing. Other girls in town began exhibiting similar symptoms, claimingthat it may have had something to do with being pinched and pricked by various residents who were seen to be of ill repute due to discrimination. This led to several women being accused of practicing witchcraft, including a beggar named Sarah Good, an elderly impoverished woman named Sarah Osburn, and an enslaved Indigenous woman named Tituba. While Good and Osburn maintained innocence, Tituba “confessed” to serving the devil. This confession was likely untrue and only made to avoid further punishment, but it emboldened the town to pursue further accusations. 

As mass hysteria swept across Salem, dozens of women were brought before panels and tribunals for questioning, and 19 people were executed. The courts were only disbanded after the wife of Governor William Phips was accused of witchcraft, as it was Phips who had established the courts to begin with. 

The Hammersmith Ghost

In December 1803, a great panic struck the community of Hammersmith, a small town just outside London. Multiple locals claimed that a ghost cloaked in a white shroud had been confronting and terrorizing residents, and it was said that the ghostly specter would appear right as the church bell struck one in the morning. Locals believed the spirit was that of a villager who had died by suicide the year before, and that his tortured soul was destined to haunt the town. Residents cowered in fear at the idea of this apparition; there was even one instance where a spooked carriage driver thought he saw the ghost before abandoning his passengers and fleeing on foot. There are other reports of women fainting to death at the sight of the purported ghost, though there was no evidence that the spirit actually existed.

Eventually, some residents of the community got their hysteria in check and determined the ghost was most likely someone in a sheet who was intentionally scaring people as a prank. Others, however, maintained that a spirit was causing havoc from beyond the grave. One such believer was Francis Smith, who one evening mistook bricklayer Thomas Millwood — who wore an all-white outfit for his profession — for the supposed ghost, and shot Millwood dead in the street. Smith went on trial and was convicted of murder, yet he still garnered sympathy from townsfolk who were hysterical with fear. Smith’s sentence was reduced to one year of imprisonment, leading to a series of debates about whether someone could be held liable for a crime based on mistaken beliefs, as Smith committed the crime only after being deluded into believing there was a ghost in the neighborhood. 

The Mad Gasser of Mattoon

Mattoon, Illinois, is a small town that was overcome by widespread panic in 1944, when reports of a “Mad Gasser” swept over the community. On September 1, a woman named Aline Kearney was overcome by a “sickening, sweet odor” that resulted in the temporary paralysis of her legs. Kearney’s husband arrived at the house shortly after and claimed to see a tall man wearing dark clothing and a tight-fitting cap standing outside the window, whom he chased until the mysterious man disappeared. Kearney’s condition returned to normal after 30 minutes, but this was just the first of many similar disturbances to come. After word spread of the Kearney incident, other townsfolk claimed they also suffered paralytic symptoms after smelling unusual odors. The panic grew to the point where chemical weapons experts were brought into the community. Armed gangs also began roaming the streets to try to find the “Mad Gasser” and bring them to justice.

There were many theories as to the identity of the mysterious menace, ranging from a chemistry teacher to an escaped Nazi prisoner of war. But in the end no assailant was ever found, and it’s highly unlikely that one ever even existed. Many of the anecdotal gassing incidents were fueled by mass hysteria, as one woman was simply overcome by odors from a spilled bottle of nail polish. It’s also theorized that years of wartime-related stress, combined with reports of chemical weapons being used overseas, added to the overall sense of communal anxiety in Mattoon.

Tanganyika Laughter Epidemic

Laughter is the best medicine, but it can also be a most perplexing symptom. In 1962, a laughter epidemic struck students at a girls’ boarding school in Tanganyika (now Tanzania). The mysterious giggles first appeared in January in a town called Kashasha, where three students began hysterically laughing from completely out of nowhere. Despite efforts to calm the girls, their perpetual howling was contagious, as dozens of other students also began experiencing laughing fits that lasted anywhere from a few hours to 16 days.

Doctors were unable to explain the phenomenon, and the root cause remains unclear even today. Some historians believe that the laughter was a visceral reaction to living in such a strict cultural environment, but that theory is far from certain. With no idea about how to quell unstoppable laughter, the school had no choice but to temporarily close in March, but that decision only led to more problems. As the girls returned home, they mysteriously “infected” each of their communities with the same insatiable urge to laugh uncontrollably. Laughter spread like wildfire throughout the country, leading to 14 separate school closures and affecting more than 1,000 people. It took roughly two yearsfor the epidemic to completely dissipate, and thankfully, nobody suffered any long-term medical effects during that time.

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