In a new report issued at the end of January, the New Your State Department of Health and its collaborating co-investigator organizations found no environmental or infectious etiologies for the mystery illness affecting 12 cases of tic-like behaviors at LeRoy High School in upstate New York near Buffalo.

The investigators now consider the outbreak to be conversion disorder, a disease category characterized by physical symptoms without an identified cause other than psychological stress. Three of the twelve students had illness associated with tic symptoms before they attended the high school (three new students with possible tic symptoms were reported during the investigation and are currently under review).

The details of the cases provided the investigators with clues. Cases ranged in age from 13-19 years and all were female. Onset of the symptoms was in the latter half of 2011 between May and December. The cases are in different grade levels and no common in-school or after school activities were identified, though four participated in soccer and two in cheerleading. No temporal relationship between vaccination with HPV vaccine and symptom onset was apparent. Significant life stressors were identified in 11 of the cases.

In interpreting the results, investigators determined that the occurrence of symptoms only in female students, the lack of faculty/staff involvement, and the range of time of symptom onset were not consistent with an environmental or infectious etiology.

Because of publicity surrounding a hypothesis put forth by the advocate Erin Broncovich about a chemical spill resulting from a train derailment, investigators checked out that area and found no cause for concern. Another diagnosis ruled out was Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococci (PANDAS) because none of the cases met the five PANDAS criteria.

Working with NIH, the state health department has offered all of the patients a no-cost specialized medical consultation to continue their care.