Epidemiology and Infection

Intestinal infections

Multistate outbreak of Salmonella serotype Typhimurium infections associated with consumption of restaurant tomatoes, USA, 2006: hypothesis generation through case exposures in multiple restaurant clusters

C. BARTON BEHRAVESHa1a2 c1, D. BLANEYa2a3, C. MEDUSa4, S. A. BIDOLa5, Q. PHANa6, S. SOLIVAa7, E. R. DALYa3, K. SMITHa4, B. MILLERa8, T. TAYLOR Jr.a9, T. NGUYENa1, C. PERRYa1, T. A. HILLa10, N. FOGGa10, A. KLEIZAa11, D. MOORHEADa11, S. AL-KHALDIa10, C. BRADENa1 and M. F. LYNCHa1

a1 Division of Foodborne, Waterborne, and Environmental Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA

a2 Epidemic Intelligence Service, Scientific Education and Professional Development Program Office, Division of Applied Sciences, Centers for Disease Control and Prevention, Atlanta, GA, USA

a3 Division of Public Health Services, New Hampshire Department of Health and Human Services, Concord, NH, USA

a4 Minnesota Department of Health, St. Paul, MN, USA

a5 Michigan Department of Community Health, Lansing, MI, USA

a6 Connecticut Department of Public Health, Hartford, CT, USA

a7 Massachusetts Department of Public Health, Jamaica Plain, MA, USA

a8 Minnesota Department of Agriculture, St. Paul, MN, USA

a9 Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA

a10 U.S. Food and Drug Administration, College Park, MD, USA

a11 U.S. Food and Drug Administration, Cincinnati District Office, Cincinnati, OH, USA

SUMMARY

Multiple salmonellosis outbreaks have been linked to contaminated tomatoes. We investigated a multistate outbreak of Salmonella Typhimurium infections among 190 cases. For hypothesis generation, review of patients' food histories from four restaurant-associated clusters in four states revealed that large tomatoes were the only common food consumed by patients. Two case-control studies were conducted to identify food exposures associated with infections. In a study conducted in nine states illness was significantly associated with eating raw, large, round tomatoes in a restaurant [matched odds ratio (mOR) 3·1, 95% confidence interval (CI) 1·3–7·3]. In a Minnesota study, illness was associated with tomatoes eaten at a restaurant (OR 6·3, mid-P 95% CI 1·05–50·4, P=0·046). State, local and federal regulatory officials traced the source of tomatoes to Ohio tomato fields, a growing area not previously identified in past tomato-associated outbreaks. Because tomatoes are commonly eaten raw, prevention of tomato contamination should include interventions on the farm, during packing, and at restaurants.

(Received October 27 2011)

(Revised December 14 2011)

(Accepted December 21 2011)

(Online publication January 20 2012)

Correspondence:

c1 Author for correspondence: C. Barton Behravesh, MS, DVM, DrPH, Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic Infectious Diseases, Division of Foodborne, Waterborne, and Environmental Diseases, Outbreak Response and Prevention Branch, 1600 Clifton Road NE, Mail-Stop A-38, Atlanta, GA 30333, USA. (Email: CBartonBehravesh@cdc.gov)

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