Mass sociogenic illness in a youth center

In July, 1989, 63 (42%) of 150 children ages 4-14 years attending an outreach program at a youth center in Florida, but no employees, developed acute and rapidly resolving upper gastrointestinal symptoms 2 to 40 minutes after a prepackaged lunch. All ill children were sent to 3 local hospital emergency departments for evaluation. However, clinical evaluation was normal for all. Of 102 children who ate any prepackaged foods, 48 (47%) became ill compared to 1/19 (5%) for children who did not eat (rate ratio [RR] = 8.9; 95% confidence interval [CI]: 1.3-60.9). No employees ate any of the food items served. Consumption of sandwiches was associated with a moderate increased risk of illness (RR = 1.7, 95% CI: 1.0-2.9). The attack rate did not differ by age, but was greater for girls (39/56, 70%) than for boys (9/46, 20%; [RR = 3.6, 95% CI: 1.9-6.6]). Over 3,000 similar prepackaged meals from the same caterer were served in the same area of Florida that day. An inquiry in the area documented absence of similar symptoms elsewhere. Unopened meal samples tested negative for pesticide residues, heavy metals, staphylococcal toxin, or Bacillus cereus. We diagnosed the outbreak as mass sociogenic illness. Complaints of a bad tasting sandwich by the index case and possible staff anxiety about food poisoning may have contributed to the development of the outbreak.