We used whole-genome sequencing data to investigate historical Listeria monocytogenes clinical (n = 1,046) and nonclinical (n = 1,325) isolates from New York, USA. Applying a threshold of 10 years apart; 33 clusters included isolates from the same or contiguous counties. Seventeen clusters included food and environmental isolates highly related to clinical isolates. These findings suggest that some listeriosis clusters can be local and span a long period, demonstrating the importance of investigating small, localized listeriosis cases with closely related isolates, even over long timeframes.
Samut et al. (2025) studied this question.