Epidemiology and Infection

Original Papers

Recurrent multistate outbreak of Salmonella Newport associated with tomatoes from contaminated fields, 2005

S. K. GREENEa1a2 c1, E. R. DALYa3, E. A. TALBOTa3a4, L. J. DEMMAa1a5, S. HOLZBAUERa1a5, N. J. PATELa1, T. A. HILLa6, M. O. WALDERHAUGa6, R. M. HOEKSTRAa1, M. F. LYNCHa1 and J. A. PAINTERa1

a1 Division of Foodborne, Bacterial, and Mycotic Diseases, National Center for Zoonotic, Vectorborne, and Enteric Diseases, 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 Division of Public Health Services, New Hampshire Department of Health and Human Services, Concord, NH, USA

a4 Dartmouth Medical School, Hanover, NH, USA

a5 Atlanta Research and Education Foundation, Atlanta, GA, USA

a6 Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD, USA

Abstract

Salmonella Newport causes more than an estimated 100 000 infections annually in the United States. In 2002, tomatoes grown and packed on the eastern shore of Virginia contaminated with a pan-susceptible S. Newport strain caused illness in 510 patients in 26 states. In July–November 2005, the same strain caused illness in at least 72 patients in 16 states. We conducted a case-control study during the 2005 outbreak, enrolling 29 cases and 140 matched neighbourhood controls. Infection was associated with eating tomatoes (matched odds ratio 9·7, 95% confidence interval 3·3–34·9). Tomatoes were traced back to the eastern shore of Virginia, where the outbreak strain was isolated from pond water used to irrigate tomato fields. Two multistate outbreaks caused by one rare strain, and identification of that strain in irrigation ponds 2 years apart, suggest persistent contamination of tomato fields. Further efforts are needed to prevent produce contamination on farms and throughout the food supply chain.

(Accepted March 28 2007)

(Online publication May 03 2007)

Correspondence:

c1 Author for correspondence: Dr S. K. Greene, Enteric Diseases Epidemiology Branch, Centers for Disease Control and Prevention, 1600 Clifton Rd., MS D-63, Atlanta, GA 30333, USA. (Email: SGreene1@cdc.gov)

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