Escherichia coli O157 infection causes approximately 70,000 diarrheal illnesses each year in the United States. These can result in hemolytic-uremic syndrome and death.
Environmental contamination with E. coli O157 may be a public health problem.
In this study, physicians from the United States identified risk factors for E. coli O157 infection during an outbreak investigation. They evaluated environmental contamination as a possible cause of this outbreak.
The team evaluated 23 cases and 53 age-matched controls who had attended the Lorain County fair in Ohio in August 2001.
|Specimens collected 42 weeks after the fair grew the same E. coli O157 strain.|
|Journal of the American Medical Association|
Cases had laboratory-confirmed E. coli O157 infection, hemolytic-uremic syndrome, or bloody diarrhea within 7 days of attending the fair.
In comparison, controls attended the fair, but did not have diarrhea.
The physicians identified the risks for infection. They also identified isolates of E. coli O157 from environmental specimens.
The team found that 26% of the cases were hospitalized, while 9% developed hemolytic-uremic syndrome.
They determined that cases were more likely than controls to have visited a particular building at the fair.
Furthermore, among visitors to this building, illness was associated with attending a dance in the building, handling sawdust from the floor, or eating and/or drinking in the building.
The physicians determined that 44% of specimens collected from the building 6 weeks after the fair grew Shiga toxin-producing E. coli O157.
They found that isolates from sawdust, rafters, and other surfaces were identical to isolates obtained from patients.
In addition, sawdust specimens collected 42 weeks after the fair grew the same E. coli O157 strain.
Dr Jay Varma's team concluded, "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".