Describe how history repeated itself in two instances of mass hysteria and in the use of propaganda after the Salem Witch trials

Periodically throughout recorded history, puzzling instances of psychiatric and neurologic symptoms have presented en mass : outbursts of thrashing and screaming, or je rky spasms and abrupt vocal tics affecting a group of individuals at once and often attributed to causes like possession, witchcraft, and malingering. Such occurrences of so-called "mass hysteria" continue to confound the medical community, but growing experience has improved the understanding and approach to these seemingly contagious psychogenic events.