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. 2019 Aug;25(8):1461-1468.
doi: 10.3201/eid2508.180761.

Multistate Outbreak of Listeriosis Associated with Packaged Leafy Green Salads, United States and Canada, 2015-2016

Julie L Self, Amanda Conrad, Steven Stroika, Alikeh Jackson, Laura Whitlock, Kelly A Jackson, Jennifer Beal, Allison Wellman, Marianne K Fatica, Sally Bidol, Paula Pennell Huth, Meghan Hamel, Kristyn Franklin, Lorelee Tschetter, Christine Kopko, Penelope Kirsch, Matthew E Wise, Colin Basler

Multistate Outbreak of Listeriosis Associated with Packaged Leafy Green Salads, United States and Canada, 2015-2016

Julie L Self et al. Emerg Infect Dis. 2019 Aug.

Abstract

We investigated an outbreak of listeriosis detected by whole-genome multilocus sequence typing and associated with packaged leafy green salads. Nineteen cases were identified in the United States during July 5, 2015-January 31, 2016; isolates from case-patients were closely related (median difference 3 alleles, range 0-16 alleles). Of 16 case-patients interviewed, all reported salad consumption. Of 9 case-patients who recalled brand information, all reported brands processed at a common US facility. The Public Health Agency of Canada simultaneously investigated 14 cases of listeriosis associated with this outbreak. Isolates from the processing facility, packaged leafy green salads, and 9 case-patients from Canada were closely related to US clinical isolates (median difference 3 alleles, range 0-16 alleles). This investigation led to a recall of packaged leafy green salads made at the processing facility. Additional research is needed to identify best practices and effective policies to reduce the likelihood of Listeria monocytogenes contamination of fresh produce.

Keywords: Canada; Listeria monocytogenes; United States; bacteria; food safety; foodborne infections; lettuce; listeriosis; outbreak; packaged leafy green salads; produce.

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Figures

Figure 1
Figure 1
Outbreak-related cases of listeriosis (n = 19) in the United States by state of residence, July 5, 2015–January 31, 2016.
Figure 2
Figure 2
Timeline of Listeria monocytogenes isolation for 19 US patients during outbreak associated with packaged leafy green salads, July 5, 2015–January 31, 2016.
See this image and copyright information in PMC

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