Investigation of factors affecting mass psychogenic illness in employees in a fish-packing plant

This study of the factors affecting the development of mass psychogenic illness (MPI) was carried out in a large fish‐packing plant in New Brunswick, Canada. A total of 269 out of 270 plant employees (99.6%) participated in the study and of these, 208 cases were affected with symptoms of MPI and 61 controls were unaffected over a period of 2½ months. A questionnaire was administered to participating employees to collect information about symptoms, demographic factors, work history, pre‐existing medical problems, potential workplace triggering exposure factors, and various psychosocial factors. Multiple logistic regression indicated that the main factors associated with MPI, in decreasing order of importance, were skill creation in the job, odor perception, and female sex. Management of this incident required reassurance of employees that there was no hazardous exposure in the plant as well as recognition of the need to reduce underlying sources of stress in the work environment. Am. J. Ind. Med. 32:90‐96, 1997. © 1997 Wiley‐Liss, Inc.