An outbreak of Escherichia coli O157 infection following exposure to a contaminated building.
BACKGROUND
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.


OBJECTIVE
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.


METHODS
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.


METHODS
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.
Varma
Jay K
JK
Foodborne and Diarrheal Diseases Branch, Division of Bacterial and Mycotic Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Ga., USA. jvarma@cdc.gov
Greene
Katherine D
KD
Reller
Megan E
ME
DeLong
Stephanie M
SM
Trottier
Janine
J
Nowicki
Scott F
SF
DiOrio
Mary
M
Koch
Elizabeth M
EM
Bannerman
Tammy L
TL
York
Steven T
ST
Lambert-Fair
Mary-Ann
MA
Wells
Joy G
JG
Mead
Paul S
PS
D000293:Adolescent; D000328:Adult; D016902:Air Pollution, Indoor / Q000009:adverse effects / Q000032:analysis; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D003967:Diarrhea / Q000453:epidemiology / Q000382:microbiology; D004196:Disease Outbreaks; D004781:Environmental Exposure / Q000009:adverse effects / Q000032:analysis; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000209:etiology; D019453:Escherichia coli O157 / Q000302:isolation & purification*; D005260:Female; D006463:Hemolytic-Uremic Syndrome / Q000453:epidemiology / Q000209:etiology; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D009820:Ohio / Q000453:epidemiology; D012307:Risk Factors