Which situations, if any, in contemporary life might cause an American town to be afflicted with general hysteria?

One of the factors that made the witch hunt and the Red Scare so frightening was the fact that one could not simply look at another person and know, without a doubt, that they were either loyal and honest or deceitful and dangerous. It is easy for fear and hysteria to develop when a person feels as though they have no real ability to protect themselves and their loved ones from harm. Miller even once called it a type of guerrilla warfare: waging war on an invisible enemy, one that you cannot pick out from other innocent people. It is then that individuals start to question those they have known for years, second-guessing every statement and interaction, and accusing their neighbors. Any town in which people come to fear a threat they cannot easily identify—perhaps a disease that has no symptoms until it kills its victim or a secret ring of serial murderers (who are hiding in plain sight)—could be susceptible to hysteria.

Given that Arthur Miller wrote The Crucible as an allegory to McCarthyism, one could come up with numerous situations that could mirror the general hysteria illustrated in the play. Hysteria is defined as an exaggerated or uncontrollable emotion or excitement among a group of people. Similar to how McCarthyism targeted communist sympathizers by making unsubstantiated claims toward influential American citizens regarding collusion with the Soviet Union, our current administration could begin targeting United States citizens by accusing them of colluding with Russia or North Korea. Given the current geopolitical environment concerning North Korea's access to nuclear weapons and capabilities, hysteria regarding a nuclear attack could sweep through the nation at any moment. Hysteria regarding the influx of illegal immigrants or the presence of ISIS throughout our nation are other possible instances that could create an atmosphere of hysteria throughout our country or a certain town in America. Even a situation involving mysterious deaths of one or more citizens could result in hysteria throughout a town or nation.
https://www.dictionary.com/browse/hysteria