The concept of mass hysteria is rather chilling to consider.
Investigators have also found that in cases of mass hysteria, one child is often an “index case” that triggers waves of anxiety.
mass hysteria n.
Spontaneous, en masse development of identical physical or emotional symptoms among a group of individuals, as in a classroom of schoolchildren.
A socially contagious frenzy of irrational behavior in a group of people as a reaction to an event.