Investigation of a large foodborne outbreak of ETEC at a corporation – Illinois, 2004

Abstract

Purpose Enterotoxigenic Escherichia coli (ETEC) is an important cause of illness worldwide but is infrequently identified as the cause of foodborne disease outbreaks in the United States. Methods During a foodborne outbreak at an Illinois corporation, a questionnaire was administered to both ill and well persons to characterize the illness and to identify its likely source. Stool samples were negative for enteric pathogens but were submitted to the Illinois Department of Public Health (IDPH) Division of Laboratories and to CDC for norovirus and ETEC testing. An environmental investigation was conducted at the food preparation facility. A case of illness caused by ETEC was defined as onset of diarrhea and at least one additional symptom of cramps, vomiting, nausea, headache, or anorexia after consuming food or beverages served at the corporation on September 23, 2004. Results One hundred eleven ill and 29 well persons were interviewed during the investigation. All ill persons had only one meal in common. Eating cucumber salad (odds ratio = 12.1; 95% confidence interval = 2.9–50.5) was identified as having a statistically significant association with being ill. Multiple serotypes of ETEC were detected in stool samples from six ill persons at IDPH and CDC laboratories. No food was available for testing. The environmental investigation revealed no critical violations or ill food-service employees. Conclusion This foodborne outbreak was caused by ETEC contamination of one or more ingredients in cucumber salad. Contamination may have been caused by the use of human waste to fertilize, irrigate, or wash the produce items. Identifying and eliminating these food contamination sources is crucial to protecting the food supply from ETEC contamination.