An Outbreak of Escherichia coli O157 Infection Following Exposure to a Contaminated Building
...n as a possible cause of the outbreak.¡± The key participants were a total of 23 case-control patients (15 years of age) and 53 age-matched controls who attended the Lorain County, Ohio, fair between August 20 and August 26, 2001. The case-patients had laboratory-confirmed E coli O157 infection, hemolytic-uremic syndrome, or bloody diarrhea within 7 days of attending the fair; the controlled patients attended the fair and did not have diarrhea. All of the laboratory-confirmed patients were interviewed by the Lorain County General Health District, as wells as the 88 persons who called to report illnesses. The case-control patients were identified by developing diarrhea within 7 days after attending the fair, had laboratory-confirmed E coli 0157, or bloody diarrhea, and the first diarrheal illness in the house. The controls were persons who attended the fair and did not have diarrhea between August 20 and September 1, 2001. These patients were excluded from the case-control group if there was any other member of the household with diarrhea during this designated time gap. They were identified by using 2 different rosters of fair attendees available to the health department. The households that were selected for the telephone interviews were randomly selected, and only one person from each house was used as a control. The main objective was to obtain 2 controls per case with 1 control from each roster. During the questionnaire, the subjects were asked a series of questions that focused on clinical history, food and drinks consumed, vendors visited, animal contact, and other fair activities. A month later, between October 10 and October 12, 2001, a follow up questionnaire was administered to all those who completed the first questionnaire. There was a fecal specimen, from the case-patients, that was sent to the Ohio Department of Health Laboratory for culture. The fair grounds were visited on three different occasions; 6, 14, and 42 weeks after the final of the fair. During this time, environmental specimens such as sawdust and swabs of surfaces were taken, refrigerated and then shipped to the Centers for Disease Control and Prevention, and cultured within 48 hours. The specimens were enriched in soy broth at 35¢ªC, and then followed by a second enrichment with more soy broth at 42¢ªC and immunomagnetic separation. In few selected patients and environmental isolates, the Shiga-toxin gene (the toxin that eventually harvests E coli O157) was detected by the use of established primers. After the experiment was...