Listeria, Then and Now: A Call to Reevaluate Patient Teaching Based on Analysis of US Federal Databases, 1998-2016

Listeria monocytogenes is a foodborne pathogen capable of crossing the placental-fetal barrier; infection with the bacterium causes listeriosis. An exposed fetus may suffer blindness, neurological damage including meningitis, or even death. The adverse consequences of listeriosis place the infection on the federally reportable disease list. Primary prevention relies on women avoiding 6 categories of foods most likely to be contaminated with L monocytogenes, as indicated in guidelines developed by the Centers for Disease Control and Prevention (CDC), adapted by the American College of Obstetricians and Gynecologists (ACOG) in 2014, and reaffirmed without changes by ACOG in 2016. This report contains a critical evaluation of United States listeriosis prevention guidelines.

Between 1998 and 2016, there were 876 identified listeriosis events documented in the illness and recall databases maintained by the CDC, Food and Drug Administration (FDA), and United States Department of Agriculture - Food Safety and Inspection Service (USDA-FSIS). Each contaminated food was manually compared to the existing listeriosis avoidance guidelines, placing each event within or outside the guidelines. Trends were analyzed over time.

Database analysis demonstrates that prior to the year 2000, abiding by the current guidelines would have prevented all reported listeriosis cases. However, in 2015 and 2016, only 5% of confirmed L monocytogenes infections originated from the 6 food groups listed in the CDC and ACOG guidelines. Similar trends emerged for food processing plant recalls (USDA-FSIS database) and grocery store recalls (FDA database). The total number of listeriosis illnesses in the United States doubled from 2007 to 2014.

A gradual shift in detection of L monocytogenes contamination in ready-to-eat meals, frozen foods, and ready-to-eat salads has occurred. Another emerging culprit is pasteurized dairy products. Revision of listeriosis avoidance guidelines by a consensus-seeking, multidisciplinary task force, is needed.