Recent cases of listeriosis were attributed to the consumption of contaminated ice cream and caramel-dipped apples.  The association with these foods was unexpected because they were not known to support growth of L. monocytogenes.  However, environmental contamination in the packing or production facilities was prevalent.  Whole genome sequences (WGS) of environmental isolates were found to be highly related to those isolated from the patients, and food exposure data provided strong evidence of the link with these foods.  Use of new epidemiological tools, such as WGS, will likely result in identifying more frequent, but potentially smaller, outbreaks.  As a result, additional foods that were previously considered to be "low risk" may be identified as the source of foodborne illness. Findings from these investigations reinforce the need for rigorous and practical environmental controls to limit contamination in foods.

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