Citation Needed

Mass psychogenic illness (MPI), also called mass sociogenic illness, mass psychogenic disorder, epidemic hysteria, or mass hysteria, involves the spread of illness symptoms through a population where there is no infectious agent responsible for contagion.[1] It is the rapid spread of illness signs and symptoms affecting members of a cohesive group, originating from a nervous system disturbance involving excitation, loss, or alteration of function, whereby physical complaints that are exhibited unconsciously have no corresponding organic causes.[2]