Occupational mass psychogenic illness. History, prevention, and management.

Occupational mass psychogenic illness is a poorly understood phenomenon that is probably underreported in the literature. Several recent outbreaks illustrate the main features, including explosive onset usually triggered by a physicochemical stimulus; disproportionate involvement of relatively uneducated, low-paid women who perform highly routine tasks; diverse symptoms with scarcity of physical signs or laboratory findings; frequent absence of usual symptoms caused by the putative contaminant; recurrences in affected individuals when they congregate; and benign morbidity and lack of sequelae. Inappropriate handling of these outbreaks can lead to prolonged employee disability and disrupted production. Though the etiology of epidemic psychogenic illness often remains uncertain, a sufficient body of knowledge exists to plan a rational prevention and management program.