As officials in Le Roy, N.Y., continue to reassure worried parents that their high school is safe, one doctor says that social media may be spreading the mysterious twitching symptoms that have plagued more than a dozen teens and at least one adult in this upstate New York town.  

The Tourette's-like symptoms have been diagnosed by a neurologist who has treated at least 10 of the affected teen girls as conversion disorder, a psychological condition once known as "mass hysteria," in which psychological stress causes physical symptoms. Dr. Laszlo Mechtler said that with treatment, the girls are getting better.  As publicity around the case continues, new teens have posted videos of themselves twitching on Facebook, YouTube and other websites.

Dr. David Lichter, a professor of neurology at the University of Buffalo who has seen one of the patients, says social media could be spreading the tics, in an instance of video gone viral.

"If you are a person who is vulnerable in some way, because of your own stresses or anxieties, I think there is a potential for that to create further spread beyond the area that was initially involved," Lichter told TODAY.

Related: What is conversion disorder?

Related: More on how social media could spread twitching hysteria

Meanwhile, angry parents blasted school officials at a public meeting over the weekend, demanding answers and more reassurance that the school is safe. Environmental activist Erin Brokovich has dispatched a team to Le Roy to investigate whether the illness could be realted to a train derailment and chemical spill that happened near the school more than 40 years ago.

The Le Roy school district posted a long letter on its web page with links to the state Department of Health's investigation, which concluded that nothing infectious or environmental was to blame for the twitching illness. The school district noted that the fact the illness began and is concentrated in one group of teenage girls points to non-environmental causes:

"In closing, we have worked for the past several months with experts and professionals both medical and environmental to better understand this condition.  Extensive research, examination, and testing have revealed that there is no environmental or infectious cause for this ailment. Environmental causes do not discriminate.  We would see a widespread impact across all age groups and genders."

In an earlier interview with TODAY, Mechtler explained that the diagnosis of coversion disorder does not mean that the symptoms aren't real or the patients aren't really suffering.

“This is a subconscious effect that occurs in patients that may be prone to anxiety or mood disorders,” he explained. “But these are definitely real symptoms. It sounds like an infectious disease, but should not be perceived as one. The state department of health made a complete review of the air quality and mold - and everything was negative so we do not think this has an infectious cause.”

Related: Teens' mystery illness diagnosed as mass hysteria

What do you think of the latest development in the "mystery illness" investigation? Sound off on our Facebook page.

The day after TODAY reported on the baffling case of 12 teenage girls at one school who mysteriously fell ill with Tourette's-like symptoms of tics and verbal outbursts, a doctor who is treating some of the girls has come forward to offer an explanation. Dr. Laszlo Mechtler, a neurologist in Amherst, N.Y., says the diagnosis is "conversion disorder," or mass hysteria.

"It's happened before, all around the world, in different parts of the world. It's a rare phenomena. Physicians are intrigued by it," Mechtler told TODAY on Wednesday. "The bottom line is these teenagers will get better."

On the show Tuesday, psychologist and TODAY contributor Dr. Gail Saltz noted that just because the girls' symptoms may be psychological in origin doesn't make them any less real or painful.

“That’s not faking it. They’re real symptoms,” Saltz continued. “They need a psychiatric or psychological treatment. Treatment does work.’’

Conversion disorder symptoms usually occur after a stress event, although a patient can be more at risk if also suffering from an illness. Symptoms may last for days or weeks and can include blindness, inability to speak, numbness or other neurologic problems.

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It's unclear which of the girls first showed symptoms, or whether any particular event triggered the outbreak. High school cheerleader and art student Thera Sanchez says her tics, stammer and verbal outbursts appeared out of the blue after a nap one day last October.

“I was fine. I was perfectly fine. There was nothing going on, and then I just woke up, and that’s when the stuttering started,” Sanchez told TODAY.

“I’m very angry,’’ Sanchez told TODAY’s Ann Curry during an interview Tuesday. “I’m very frustrated. No one’s giving me answers.’’

The New York State Health Department has been investigating the case for more than three months and says the school building is not to blame. Officials from the LeRoy Junior-Senior High School in upstate New York, where all the girls attended when their symptoms began, have released environmental reports, conducted by an outside agency, showing no substances in any of the school buildings that could cause health problems.

Health officials ruled out carbon monoxide, illegal drugs and other factors as potential causes. Officials say no one at the school is in any danger.

“We have conclusively ruled out any form of infection or communicable disease and there’s no evidence of any environmental factor,’’ Dr. Gregory Young of the New York Department of Health told NBC News.

Related: Click here to read the school district's statement and full environmental reports

But some of the girls' parents say they're not satisfied with the explanations so far.

"Obviously we are all not just accepting that this is a stress thing," Jim Dupont, father of one of the affected girls, told TODAY on Wednesday. "It's heart wrenching, you fear your daughter's not going to have a normal life."

Read the original story: Girls' medical mystery baffles doctors

Scott Stump, Rebecca Dube and NBC News contributed to this report.

What's your theory? Discuss on our Facebook page.

Jan. 18 update: The day after TODAY reported on the baffling case of 12 teenage girls at one school who mysteriously fell ill with Tourette's-like symptoms of tics and verbal outbursts, a doctor who is treating some of the girls has come forward to offer an explanation. Dr. Laszlo Mechtler, a neurologist in Amherst, N.Y., says the diagnosis is "conversion disorder," or mass hysteria.

"It's happened before, all around the world, in different parts of the world. It's a rare phenomena. Physicians are intrigued by it," Mechtler told TODAY. "The bottom line is these teenagers will get better."

Tuesday on the show, psychologist and TODAY contributor Dr. Gail Saltz noted that just because the girls' symptoms are psychological in origin doesn't make them any less real or painful.

“That’s not faking it. They’re real symptoms,” Saltz continued. “They need a psychiatric or psychological treatment. Treatment does work.’’

Officials from the LeRoy Junior-Senior High School in upstate New York, where all the girls attended when their symptoms began, have released environmental reports, conducted by an outside agency, showing no substances in any of the school buildings that could cause health problems.

Related: Click here to read the school district's statement and full environmental reports

But some of the girls' parents say they're not satisfied with the explanations so far.

"Obviously we are all not just accepting that this is a stress thing," Jim Dupont, father of one of the affected girls, told TODAY. "It's heart wrenching, you fear your daughter's not going to have a normal life."

Read the original story, below.

High school cheerleader and art student Thera Sanchez  took a quick nap one day last October, and when she woke up, the life she had known was gone.

In its place, she was plagued by uncontrollable body movements, tics and verbal outbursts, similar to Tourette’s syndrome. It turned out Sanchez was not alone, as she is one of 12 girls from LeRoy Junior-Senior High School in upstate New York who has been exhibiting symptoms of a mysterious condition that has baffled doctors.

“I’m very angry,’’ Sanchez told TODAY’s Ann Curry during an interview Tuesday. “I’m very frustrated. No one’s giving me answers.’’

Sanchez appeared on TODAY alongside her mother, Melisa Phillips, as well as another one of the girls experiencing the symptoms, Katie Krautwurst, and her mother, Elizabeth Miller.

The mothers of the two girls are fighting for answers after state health officials determined that nothing at the high school itself could have triggered the mass illness. Each girl has been examined by a private doctor and given a diagnosis. After a three-and-a-half month investigation, health officials ruled out carbon monoxide, illegal drugs and other factors as potential causes.  Officials say no one at the school is in any danger.

Related: Click here to read the school district's statement and full environmental reports

“We have conclusively ruled out any form of infection or communicable disease and there’s no evidence of any environmental factor,’’ Dr. Gregory Young of the New York Department of Health told NBC News.

“Where’s the proof?’’ Phillips asked on TODAY. “Where’s the data? Where’s the testing? When has this been done? Nothing’s been collectively done for our daughters. Everything has been done individually. Testing they say that all the girls have had, they have not had. The facts that they’re stating just aren’t true.’’

The girls did not say what diagnosis they have been given, only that doctors have told them the onset of their symptoms was stress-related.

Sanchez, a 17-year-old senior and former cheerleader, displayed uncontrollable movements and verbal tics during the interview, while the symptoms of Krautwurst, a high school junior, were not as pronounced.  

“Mine’s more advanced, I think, because I’ve had it longer, but it’s definitely gotten better,’’ said Krautwurst.  Meanwhile, Sanchez said her own condition is getting worse.

On Oct. 7, Sanchez took a power nap, and when she woke up, she started stuttering uncontrollably and has been exhibiting her symptoms ever since, according to her mother. Since then, she has quit cheerleading and regularly attending her beloved art classes.

“Mostly that it’s stress-induced,’’ Sanchez said about what doctors told her. “I was fine. I was perfectly fine. There was nothing going on, and then I just woke up, and that’s when the stuttering started.”

“I can’t explain it,’’ Krautwurst said. “They told us it was traumatic, but I really don’t think any of us had that traumatic of a life before.’’

Psychologist and TODAY contributor Gail Saltz said she could not make any specific diagnosis having just met the girls, but she stressed that just because the cause may be psychological doesn’t mean the symptoms – or the pain the girls are experiencing – is fake.

“When you’ve ruled everything out and they’re saying to you it’s stress-related, then you might call it something called ‘conversion disorder’ or ‘psychosomatic illness,’ which means that symptoms have been converted from something psychological into something physical,’’ Saltz said. “It usually is predated by stress.”

“That’s not faking it. They’re real symptoms,” Saltz continued. “They need a psychiatric or psychological treatment. Treatment does work.’’

For Sanchez, all she wants is to know what is happening to her and why.

“I want an answer,’’ she said. “A straight answer.’’

 What's your theory on this medical mystery? Discuss on our Facebook page.