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Outbreak of Salmonella Newport Infections Linked to Cucumbers—United States, 2014

Monday, June 15, 2015: 4:54 PM
Back Bay B, Sheraton Hotel
Kristina M. Angelo , Centers for Disease Control and Prevention, Atlanta, GA
Alvina K. Chu , Maryland Department of Health and Mental Hygiene, Baltimore, MD
Madhu Anand , New York State Department of Health, Albany, NY
Thai-An Nguyen , Centers for Disease Control and Prevention, Atlanta, GA
Lyndsay Bottichio , Centers for Disease Control and Prevention, Atlanta, GA
Matthew Wise , Centers for Disease Control and Prevention, Atlanta, GA
Sharon Seelman , Food and Drug Administration, Silver Spring, MD
Rebecca Bell , Food and Drug Administration, Silver Springs, MD
Marianne Fatica , Food and Drug Administration, Silver Springs, MD
Deanna Baldwin , Maryland Department of Agriculture, Annapolis, MD
Kyle Shannon , Maryland Department of Health and Mental Hygiene, Baltimore, MD
Hannah Lee , Maryland Department of Health and Mental Hygiene, Baltimore, MD
Errol Strain , Food and Drug Administration, Silver Springs, MD
Eija Trees , Centers for Disease Control and Prevention, Atlanta, GA
Laura Gieraltowski , Centers for Disease Control and Prevention, Atlanta, GA
Audio File Recorded Presentation

BACKGROUND:  Salmonella causes approximately 1 million foodborne infections and 400 deaths annually in the United States. In August 2014, PulseNet, the national molecular subtyping network for foodborne disease surveillance, detected a multistate cluster of Salmonella Newport infections with an indistinguishable pulse-field gel electrophoresis pattern (JJPX01.0061) in the eastern United States.  Previous outbreaks with this strain in the eastern US have been linked to tomatoes from the Delmarva Peninsula. Our objectives included performing case finding, assessing common exposures, and utilizing traceback to identify a vehicle and prevent further illnesses. 

METHODS: A case was defined as illness with the outbreak strain of Salmonella Newport from May 20, 2014 to September 30, 2014.  Information was collected on travel, restaurant, and food exposures in the 7 days before illness onset using a structured questionnaire.  Reported food frequencies were compared to the 2006-2007 FoodNet Population Survey of healthy persons.  Officials in Maryland, Delaware, and New York worked with their FDA district offices and Rapid Response Teams to conduct an informational traceback to identify the source of tomatoes, cucumbers, and lettuce consumed in illness sub-clusters.  Whole genome sequencing (WGS) was conducted to further characterize relatedness of Salmonellaisolates. 

RESULTS:  A total of 275 cases from 29 states and DC were identified with the majority of cases in Pennsylvania and Maryland.  Ill persons ranged in age from <1 to 90 years (median: 42 years). Sixty-six percent (174/265) of ill persons were female.  Thirty-four percent (48/141) were hospitalized; 1 death was reported.  Interviews of 79 ill persons showed that a significantly higher percentage consumed cucumbers in the week before illness onset than expected (62% vs. 46.9%, p=0.002). Preliminary traceback from eight Maryland and Delaware sub-clusters led to a common grower on Maryland’s Eastern Shore in the Delmarva region.  Traceback from a New York restaurant sub-cluster did not lead to this grower.  Environmental samples from the common grower did not yield SalmonellaNewport. However, sampling was performed after the harvest.  WGS analysis showed that genetic sequences of clinical isolates from Maryland and Delaware were highly related but distinct from the New York sub-cluster.

CONCLUSIONS:  Epidemiologic and traceback evidence suggests cucumbers were a major source of illness in this outbreak.  This is the first multistate outbreak of this strain of Salmonella Newport infections linked to a produce item from the Delmarva Peninsula other than tomatoes, suggesting an environmental reservoir may be responsible for the recurring outbreaks linked to this region.

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