Epidemiology and Infection

Research Article

Outbreak of Salmonella Braenderup infections associated with Roma tomatoes, northeastern United States, 2004: a useful method for subtyping exposures in field investigations

S. K. GUPTAa1a2 c1, K. NALLUSWAMIa3, C. SNIDERa1a4, M. PERCHa1, M. BALASEGARAMa5, D. BURMEISTERa5, J. LOCKETTa1, C. SANDTa3, R. M. HOEKSTRAa1 and S. MONTGOMERYa1

a1 Foodborne and Diarrheal Diseases Branch, Centers for Disease Control and Prevention, Atlanta, GA, USA

a2 Epidemic Intelligence Service, Office of Workforce and Career Development, Centers for Disease Control and Prevention, Atlanta, GA, USA

a3 Pennsylvania Department of Health, Harrisburg, PA, USA

a4 Association of Schools of Public Health, Atlanta, GA, USA

a5 Centers for Disease Control and Prevention, Atlanta, GA, USA

SUMMARY

Salmonella Braenderup is an uncommon serotype in the United States. In July 2004, a multistate outbreak of Salmonella Braenderup diarrhoeal infections occurred, with 125 clinical isolates identified. To investigate, we conducted a case-control study, enrolling 32 cases and 63 matched controls. Cheese, lettuce and tomato eaten at restaurants all appeared to be associated with illness. To further define specific exposures, we conducted a second study and asked managers of restaurants patronized by patients and controls about cheese, lettuce and tomato varieties used in dishes their patrons reported consuming. This information was obtained for 27 cases and 29 controls. Roma tomatoes were the only exposure significantly associated with illness (odds ratio 4·3, 95% confidence interval 1·2–15·9). Roma tomatoes from two restaurants were traced back to a single tomato packing house. The methods used in this field investigation to define specific exposures may be useful for other foodborne outbreaks.

(Accepted November 27 2006)

(Online publication February 05 2007)

Correspondence:

c1 Author for correspondence: S. K. Gupta, M.D., M.P.H., Epidemic Intelligence Service Officer, Foodborne and Diarrheal Diseases Branch, Centers for Disease Control and Prevention, 1600 Clifton Road, NE, MS A-38, Atlanta, GA 30333, USA. (Email: scg7@cdc.gov).

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