Mass hysteria

Other names include collective hysteria, group hysteria, or collective obsessional behavior, in sociology and psychology refers to collective delusions of threats to society that spread rapidly through rumors and fear. In medicine more than one person uses the term to describe the spontaneous manifestation of the same or similar hysterical physical symptoms.

A common manifestation of mass hysteria occurs when a group of people believes they are suffering from a similar disease or ailment, sometimes referred to as mass psychogenic illness or epidemic hysteria.

As the name implies, this little-understood psychological condition sets in among a group of people typically a gaggle of young girls who spontaneously manifest the same or similar hysterical symptoms, such as seizures, convulsions or fainting. Sufferers believe they all have the same disease or illness, but in fact they're all in good physical health. A famous historical case resulted in the Salem Witch Trials of 1692. Dozens of people were accused of (and hanged for) causing several young girls in and around Salem, Mass., to have frequent seizures and convulsions. (The image shows Mary Walcott, 17, convulsing on the courthouse floor during one of the trials.) The girls were posthumously diagnosed with mass hysteria. Accusations of witchcraft no longer fly, but mass hysteria is alive and well. Recently, Thera Sanchez, a high school cheerleader in upstate New York, developed strange physical and vocal tics; this led to a dozen other girls and one boy in her school developing the same Tourette's-like symptoms. Officials initially wondered if the students were being poisoned, but psychiatrists recognized the phenomenon as a modern day case of mass hysteria. 

Mass hysteria manifesting as collective symptoms of disease is sometimes referred to as mass psychogenic illness or epidemic hysteria. Mass hysteria typically begins when an individual becomes ill or hysterical during a period of stress. After this initial individual shows symptoms, others begin to manifest similar symptoms, typically nausea, muscle weakness, fits or headache.