The sorry souls who danced til they dropped, literally

No matter how much of a raver you are, the idea of dancing and dancing until death by exhaustion no doubt sounds horrific. Tragically, that's exactly what happened to several victims of the dancing plague in Strasbourg in 1518. John Waller, who's written a book about it, described the events in the Guardian last week:

"In the year 1518, about 400 citizens of Strasbourg danced for days or weeks in succession. This time the authorities intensified the epidemic by encouraging the afflicted to keep dancing in the misguided belief that doing so would cure them. They had the dancers taken to a specially constructed stage where musicians played pipes and drums and hired dancers held them tight to prevent them from flagging. Soon people were dying of exhaustion."

The Strasbourg dancing plague is an example of mass hysteria – a kind of psychological contagion with physical consequences. Outbreaks are usually triggered by periods of prolonged stress. In Strasbourg in 1518, the community had recently suffered from famine. Meanwhile the physical manifestation of mass hysteria are usually influenced by the beliefs of the day. Waller explains:

"…the inhabitants of Strasbourg were reeling from severe famine, their morale already shattered by syphilis, smallpox and plague. They danced in their misery because people living along the Rhine and Moselle rivers had a longstanding fear of devils and saints who inflicted a terrible, compulsive dance. Having fallen into a trance state, they acted in accordance with these supernaturalist beliefs: dancing wildly for days on end."

Outbreaks of mass hysteria still occur to this day. For example, around two weeks ago, a classroom in Tanzania descended into chaos as many of the girls fell victim to a mass fainting fit.

A particularly quaint British example of mass hysteria was "railway spine": 19th century rail passengers reported feeling faint and suffering back pain – a psychological reaction that experts at the time said was due to the effect of 30 mph speeds on the human body.

Episodes of mass hysteria often seem to involve women more than men, but that certainly isn't the case with koro: the phenomenon, observed largely in S.E Asia and China, whereby men believe their penis is shrivelling completely into their body, with death the ultimate feared outcome. Koro has tended to spread during economic crises.