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Volume 26, Number 10—October 2020

Lessons Learned from a Decade of Investigations of Shiga Toxin–Producing Escherichia coli Outbreaks Linked to Leafy Greens, United States and Canada

Katherine E. MarshallComments to Author , April Hexemer, Sharon L. Seelman, Marianne K. Fatica, Tyann Blessington, Maha Hajmeer, Hannah Kisselburgh, Robin Atkinson, Kristin Hill, Davendra Sharma, Michael Needham, Vi Peralta, Jeffrey Higa, Karen Blickenstaff, Ian T. Williams, Michael A. Jhung, Matthew Wise, and Laura Gieraltowski
Author affiliations: Centers for Disease Control and Prevention, Atlanta, Georgia, USA (K.E. Marshall, H. Kisselburgh, I.T. Williams, M.A. Jhung, M. Wise, L. Gieraltowski); Public Health Agency of Canada, Ottawa, Ontario, Canada (A. Hexemer); Food and Drug Administration, College Park, Maryland, USA (S.L. Seelman, M.K. Fatica, T. Blessington, K. Blickenstaff); California Department of Public Health, Sacramento, California, USA (M. Hajmeer, M. Needham); California Department of Public Health, Richmond, California, USA (V. Peralta); California Department of Public Health, Los Angeles, California, USA (J. Higa); Canada Food Inspection Agency, Ottawa (R. Atkinson, K. Hill, D. Sharma)

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Table 2

STEC outbreaks linked to leafy greens by type of leafy green implicated, United States and Canada, 2009–2018*

Leafy green type Outbreaks with information for type of leafy green† Outbreaks with single known type of leafy green implicated Outbreak-related illnesses attributed to outbreak with single type of implicated leafy green
Romaine 16 (40) 13 (54) 617 (84)
Iceberg 7 (18) 4 (17) 54 (7)
Spinach 5 (13) 4 (17) 32 (4)
Cabbage 1 (3) 1 (4) 16 (2)
Kale 1 (3) 1 (4) 7 (1)
Green leaf 1 (3) 1 (4) 5 (0.7)
Butter lettuce 1 (3) 0 0
Radicchio 1 (3) 0 0
Spring mix 1 (3) 0 0
11 (28)‡
Total 40 24 731

*Values are no. (%) except as indicated. STEC, Shiga toxin–producing Escherichia coli
†More than 1 type of leafy green may have been reported for a given outbreak.
‡This includes two outbreaks that occurred in both the US and Canada. In 2015, the US investigation identified romaine lettuce as the outbreak source, and the Canadian investigation was not able to determine a specific type of leafy green. In 2017, the Canadian investigation linked an outbreak of STEC O157 to romaine lettuce, and the US investigation did not result in enough epidemiologic evidence to implicate a specific type of leafy green. For the purposes of this study, the leafy green type for these outbreaks was classified as unknown. For 1 outbreak, multiple leafy green types, including kale, spinach, and romaine, were reported and traced back but the leafy green type remained unknown.

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Page created: June 25, 2020
Page updated: September 16, 2020
Page reviewed: September 16, 2020
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.