Jay K. Varma, MD; Katherine D. Greene, AS; Megan E. Reller, MD; Stephanie M. DeLong, MPH; Janine Trottier, BSN; Scott F. Nowicki, MPH; Mary DiOrio, MD, MPH; Elizabeth M. Koch, MD, MPH&TM; Tammy L. Bannerman, PhD; Steven T. York, MPA; Mary-Ann Lambert-Fair, BS; Joy G. Wells, MS; Paul S. Mead, MD, MPH

JAMA. 2003;290:2709-2712.

Context:  Infection with Escherichia coli O157 causes an estimated 70 000 diarrheal illnesses per year in the United States and can result in hemolytic-uremic syndrome and death. Environmental contamination with E coli O157 may be a public health problem.

Objectives:  To determine risk factors for E coli O157 infection during an outbreak investigation at a county fair and to evaluate environmental contamination as a possible cause of the outbreak.

Design, Setting, and Participants Case-control study of 23 patients (median age, 15 years) and 53 age-matched controls who had attended the Lorain County, Ohio, fair between August 20 and August 26, 2001. Case-patients had laboratory-confirmed E coli O157 infection, hemolytic-uremic syndrome, or bloody diarrhea within 7 days of attending the fair; controls attended the fair and did not have diarrhea.

Main Outcome Measures:  Risk factors for infection and isolates of E coli O157 from environmental specimens.

Results:  Six (26%) case-patients were hospitalized and 2 (9%) developed hemolytic-uremic syndrome. Case-patients were more likely than controls to have visited building A (a multipurpose community facility on the fairgrounds; matched odds ratio [MOR], 21.4 [95% confidence interval {CI}, 2.7-170.7]). Among visitors to building A, illness was independently associated with attending a dance in the building (MOR, 7.5; 95% CI, 1.4-41.2), handling sawdust from the floor (MOR, 4.6; 95% CI, 1.1-20.0), or eating and/or drinking in the building (MOR, 4.5; 95% CI, 1.2-16.6). Twenty-four (44%) of 54 specimens collected from building A 6 weeks after the fair grew Shiga toxin–producing E coli O157. Isolates from sawdust, the rafters, and other surfaces were identical by molecular fingerprinting to patient isolates. Sawdust specimens collected 42 weeks after the fair also grew the same E coli O157 strain.

Conclusions:  Absence of evidence implicating specific food or beverage sources and the recovery of E coli O157 from the rafters suggest that airborne dispersion of bacteria contributed to the contamination. Because E coli O157 can survive in the environment for more than 10 months, humans may be at risk of infection long after an environment is initially contaminated.

Author Affiliations: Foodborne and Diarrheal Diseases Branch, Division of Bacterial and Mycotic Diseases, National Center for Infectious Diseases (Drs Varma, Reller, and Mead and Mss Greene, DeLong, Lambert-Fair, and Wells) and Epidemic Intelligence Service, Epidemiology Program Office (Drs Varma and Reller), Centers for Disease Control and Prevention, Atlanta, Ga; Lorain County General Health District, Elyria, Ohio (Ms Trottier); and Ohio Department of Health, Columbus (Messrs Nowicki and York and Drs DiOrio, Koch, and Bannerman).

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