Outbreaks of salmonella associated with Roma tomatoes

Three outbreaks of Salmonella infections associated with eating Roma tomatoes were detected in the USA and Canada in the summer of 2004.In one multistate USA outbreak during 25 Jun -18 Jul 2004, multiple Salmonella serotypes were isolated, and cases were associated with exposure to Roma tomatoes from multiple locations of a chain delicatessen. Each of the other two outbreaks was characterized by a single Salmonella serotype: Braenderup in one multistate outbreak and Javiana in an outbreak in Canada. In the three outbreaks, 561 outbreak-related illnesses from 18 states and a province in Canada were identified.

This report describes the subsequent investigations by public health and food safety agencies. Although a single tomato-packing house in Florida was common to all three outbreaks, other growers or packers also might have supplied contaminated Roma tomatoes that resulted in some of the illnesses. Environmental investigations are continuing. Because current knowledge of mechanisms of tomato contamination and methods of eradication of Salmonella in fruit is inadequate to ensure produce safety, further research should be a priority for the agricultural industry, food safety agencies, and the public health community.

In July 2004, a total of 429 culture-confirmed, outbreak-associated salmonellosis cases were identified in nine states (Maryland, Michigan, Missouri, North Carolina, New Hampshire, Ohio, Pennsylvania, Virginia, and West Virginia); these cases occurred among persons eating at delicatessen chain A sites, with symptom onset during Jul 2004 The median age of patients was 35 years (range: 1-81 years); 52 percent were male. No deaths occurred, but 30 percent of patients were hospitalized. These cases yielded Salmonella enteric serotypes Javiana, Typhimurium, Anatu, Thompson, Muenchen, and Group D untypable.

Roma tomatoes were removed from all delicatessen chain A sites on 14 Jul 2004. A total of 22 (5 percent) patients reported illness onset after 19 Jul 2004, outside the incubation period for salmonellosis. These illnesses might be explained by factors such as continued Roma tomato use, poor recall, low infectious dose, food saved and eaten later, or secondary transmission.

ProMed Mail
April 26, 2005

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