Putting the mass in mass hysteria

If you've been following medical news over the past few months, you may have heard about some goings on in a little town called Le Roy. Over 20 high school girls from Le Roy High School have developed Tourette-like tics. The symptoms are severe enough that afflicted students have dropped out of school.

After the New York State Health Department failed to identify any known toxins or infections, a neurologist from the area gave his verdict. From the New York Times:

...it was conversion disorder, he said, which meant the girls were subconsciously converting stress into physical symptoms. And because so many students were afflicted with similar symptoms, it was also considered to be mass psychogenic illness, which is another way of saying mass hysteria.

More recently, neurologist Rosario Trifiletti saw some of the patients and put forth a different theory:

... the girls were suffering from an illness similar to Pandas (Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcus), a disease in which the immune system alters the neurochemistry of young people suffering from strep infection ... [A] week later, after examining the girls, Trifiletti revealed on “Dr. Drew” that all nine of the girls he tested showed evidence of either strep exposure or exposure to the organism associated with pneumonia.

Dr. Trifiletti's patients have shown dramatic signs of improvement on antibiotics. That proves their illness is physical instead of psychological, right? Not according to skeptics of the PANDAS diagnosis; they say the antibiotics are only working as a placebo.

So who's right?

A few TV clips provide clues. Back in January, before Dr. Trifiletti arrived on the scene, the Today Show ran a couple of segments about Le Roy, interviewing some of the afflicted girls and their parents. There was a lot of footage showing the tics themselves, giving viewers a better idea of what it would be like to live with them.

Segments are here. The first tics begin at 0:22.

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Did you watch?

So did a whole lot of other people. If what's happened to these girls is purely psychological, having nothing to do with area-specific toxins or infections, why hasn't the "mass hysteria" spread across the whole country?

Are there no stressed-out, impressionable teenage girls outside of Le Roy?