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Epidemic Hysteria: School Outbreaks 1973–1993

Objective: Increased reporting of outbreaks has brought more familiarity with the syndrome but no more accurate knowledge about the nature and mechanisms of such episodes. As it has become an area for an expanding field of competitive explanations, the review is intended to find any additional epidemiological cues and any clarification about methods of investigating such outbreaks. Methods: The retrieval of data was organized upon a choice to have a homogeneous sample rather than a comprehensive one. Newspapers and sociological sources were left out. A Medline search with cross-referencing was conducted to select the outbreaks limited to the standard school type. Reports were examined from two points of view: the descriptive epidemiological parameters and the mode of reporting the outbreaks. Results: Forty-five episodes were studied. A historic shift in the manifest presentation is apparent: larger groups are involved for a shorter time. A period at risk has been identified: the last 2 months of the school calendar. The peak age of affected children is 12. A downward age spread is present in 14/20 episodes where suitable information is provided. Methods of reporting were classified into four categories: descriptive (n = 24), public health reports (n = 7), case-control (n = 7), case study (n = 7). Diagnosis of exclusion for environmental contamination is still a prevalent mode of reporting but does not make the outbreak intelligible. Conclusion: (1) A two-step approach is suggested: a simple environmental check for short and uneventful outbreaks; an intensive case study for any episode with long duration or recurrence. (2) Two hypotheses for future testing are proposed: a hypothesis of arousal, probably of a benign, age-specific, and sexual nature, in short simple cases; a hypothesis of conflict in the long or recurrent ones.