There is actually a paper analyzing listeriosis incidence and source that was recently published in the Journal of Midwifery and Women's Health.
https://onlinelibrary.wiley.com/doi/abs/10.1111/jmwh.12757
Our team found that Listeria monocytogenes contamination shifted from the traditional "don't eats" into processed foods, such as precut salads, frozen vegetables, and some pasteurized dairy.
"Results
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.
Discussion
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."
In short, "if you did not cook it, and you can't heat it, don't eat it"
We are hopeful that the CDC will eventually reevaluate its guidelines on what foods should be avoided in pregnancy. Current guidelines are over 20 years old.
In the meantime, since we are continuing to give out information that is outdated, our national rate of listeriosis cases is continuing to outpace population growth.
Regards,
the Listeria team