“If you  know not what a witch is,” asks the judge, “how do you know you are not one?”

The line appears in the 1996 film “The Crucible.” Based on Arthur Miller’s play of the same name, “The Crucible” dramatizes the events of the 1692 Salem Witch Trials. A group of young girls who enjoy dancing with one family’s slave, a woman named Tituba, are central to the story. The girls exhibit strange, unexplained symptoms, and in the chaos that follows public accusations of witchcraft, the secret lives of Salem’s residents become the subject of paranoid legal charges. Innocent people suffer and are condemned to die.

The movie, in particular, makes it clear that the girls involved are making up stories. Excited by the diversion from their day-to-day lives and perhaps enticed by the power their accusations give them, the girls wreak havoc among the Puritan townsfolk. The viewer gets the distinct impression that some of the girls are “me too” participants in the affair. They don’t want to feel left out, so they suddenly find that they, too, are the victims of malicious witchcraft.

Today, Salem, Mass. (situated amidst mile after mile of urban sprawl outside Boston), has built an almost embarrassing trade around the 1692 witch trials. You can visit the museums, gift shops and the store of famed Wiccan author Laurie Cabot (where signs caution shoppers that double-edged “athame” blades, used in Wiccan ritual, must be purchased with accompanying religious materials, lest the buyer run afoul of Massachusetts knife laws) and never make the connection: The town’s tourist industry is built on wrongful accusation and murder.

If the Salem Witch Trials spring readily to mind when you read the news from Leroy, N.Y., you are not alone. InNovember, a dozen girls from the same Upstate New York high school were diagnosed with “shaking, tics, and vocal outbursts similar to those of Tourette’s syndrome.”

State and county health officials have ruled out drug abuse, infection, environmental toxins and several other possible causes. In other words, the bizarre symptoms the girls appear to be experiencing have no discernible cause. As of this writing, three of the affected students have gone public with their parents, complaining that the authorities haven’t done enough to help them and demanding “answers.” Multiple parties interviewed or polled for pull-out quotes have insisted the girls aren’t “faking” their symptoms, even as the girls’ parents insinuate that state health officials are lying about the testing the girls have or have not received.

The interviews given thus far have been striking in their convenience. The verbal outbursts seem feigned or consciously timed. The angry expressions of dismay over the sudden onset of symptoms seem tailor-made for eager infotainment “journalists.” Genuine though it may be, the girls’ sickness is perfectly suited to dramatic displays.

The Rochester Democrat and Chronicle quotes pediatric neurologist Dr. Laszlo Mechler concerning the media fray surrounding the Leroy students. It isn’t true, he says, that doctors don’t know what’s going on or don’t know how to treat it.

“We know exactly what is going on,” he told the paper. “It’s happened before, all around the world, in different parts of the world. It’s a rare phenomenon. Physicians are intrigued by it. The bottom line is these teenagers will get better.”

What Mechler appears to be talking around – in part because HIPAA privacy regulations prevent him and his peers from commenting publicly about their patients’ medical details – is something called “conversion disorder.” The A.D.A.M. Medical Encyclopedia describes this as “a condition in which a person has blindness, paralysis, or other nervous system (neurologic) symptoms that cannot be explained by medical evaluation.” The definition continues at length in language that seems oddly defensive:

It is important to understand that patients are not making up their symptoms (malingering). Some doctors falsely believe that conversion disorder is not a real condition, and may tell patients the problem is all in their head. However, these conditions are real. They cause distress and cannot be turned on and off at will.

What we now call “conversion disorder” is what we used to call “mass hysteria.” It is this hysteria on which many blame the horrors of the Salem Witch Trials. Living in a modern, technologically saturated age, it is very easy for us to believe we are immune to the human follies of centuries past. But, as Dr. Mechler hinted, the “mass hysteria” of Salem is happening all around the world even now.

Five years ago, a sociopsychological outbreak sickened an astounding 600 girls at a school near Mexico City. Students affected exhibited nausea and “muscle atrophy.” Health officials diagnosed nearly 15 percent of the student body as suffering from “mass hysteria.”

In 2005, students and teachers at a school in Chechnya complained of seizures, fainting and respiratory problems. One hundred people, most of them adolescent girls, succumbed to the unknown malady before it was over.

In 2009, more than 1,200 workers at a yarn factory in China complained of nausea, dizziness and vomiting. Officials claimed that this, too, was “mass hysteria.” While the physical symptoms were undeniable, the cause could not be determined (although some blamed the illnesses on “toxic fumes”).

That same year, an outbreak of “mass psychogenic illness” sickened 43 people in northern Nicaragua. It came on the heels of a similar outbreak in 2003, in which 60 people were affected.

When multiple people get sick, we naturally look to the environment. Our society is rife with paranoia and conspiracy theorists, who have been quick to blame everything from demon possession to vaccinations to unseen, unspecified environmental poisons for the Leroy girls’ symptoms. Having eliminated any reasonable external cause, however, we must look to the girls themselves. Reluctant though we may be to admit it, what is bothering them is nothing new.

We don’t know exactly what it is because we can find no physical cause. We know, however, what it is not: It is not witchcraft … and it probably is not “real” as most of us would define the word.

Note: Read our discussion guidelines before commenting.