In the 1400’s, a nun in a French convent started making sounds like a cat. Other nuns began to do the same. Eventually, they started biting one another. As word of the bitings spread, so, too, did the bitings. They swept through other convents all the way to Rome.In July of 1518, people in Strasbourg, then part of the Holy Roman Empire, began dancing. It started with Frau Troffea. Others began to join in, and soon there were 400 dancers. Some died as a result of the nonstop dancing that went on for a month. They could not stop.In 1692, colonists in New England began having fits. Demonic possession was a suggestion. The epileptic-like fits led to the Salem witch trials. In 2008 in Tanzania, female students started fainting for no reason. In 2011, students in Le Roy, N.Y., developed Tourette’s-like symptoms that went unexplained.