A large outbreak of brainerd diarrhea associated with a restaurant in the Red River Valley, Texas

Background. In June 1996, an outbreak of chronic diarrhea was reported to the Texas Department of Health ( Austin). Methods. We initiated active case finding, performed 2 case-control studies, and conducted an extensive laboratory and environmental investigation. Results. We identified 114 persons with diarrhea that lasted >= 4 weeks. Symptoms among 102 patients who were studied included urgency ( 87%), fatigue ( 86%), fecal incontinence ( 74%), and weight loss ( 73%); the median maximum 24-h stool frequency was 15 stools. Diarrhea persisted for > 6 months in 87% and for > 1 year in 70% of patients who were observed. Fifty-one ( 89%) of 57 ill persons had eaten at a particular restaurant within 4 weeks before onset, compared with 8 ( 14%) of 59 matched control subjects ( matched odds ratio [ OR], undefined; 95% confidence interval [ CI], 11.2-infinity). At the restaurant, patients were more likely than their unaffected dining companions to have drunk tap water ( OR, 2.8; 95% CI, 1.0-9.9) and to have eaten several specific food items, and they were less likely to have drunk iced tea made from boiled water and store-bought ice ( OR, 0.3; 95% CI, 0.05-1.0). A multivariable model that included consumption of tap water and salad bar tomatoes best fit the data. The restaurant had multiple sanitary and plumbing deficiencies. Extensive laboratory and environmental testing for bacterial, parasitic, mycotic, and viral agents did not identify an etiologic agent. Conclusions. The clinical, laboratory, and epidemiologic findings are consistent with those of previous outbreaks of Brainerd diarrhea. To our knowledge, this is the largest reported outbreak of Brainerd diarrhea associated with a restaurant.