To help minimize the public health burden of listeriosis, USDA’s Food Safety and Inspection Service (FSIS) and the U.S. Food and Drug Administration (FDA) have conducted a major study to better understand the risk of foodborne illness associated with eating certain foods prepared in retail delicatessens and developed recommendations for changes in current practices that may improve the safety of those products.

The study, a quantitative risk assessment, provides a scientific evaluation of the risk of listeriosis associated with consumption of meats, cheeses and other ready-to-eat foods prepared in retail delis. It also examines interventions that limit the survival, growth or transmission of Listeria monocytogenes (Lm), the bacteria that causes listeriosis.

Control of Lm has long been an objective of the public health community. The Centers for Disease Control and Prevention estimates that infections with Lm cause about 1,600 illnesses, 1,500 hospitalizations and 260 deaths in the United States each year. Listeriosis is rare, but its fatality rate is very high (i.e., about 16 percent, compared with 0.5 percent for either Salmonella or E. coli O157:H7). It primarily affects older adults, pregnant women, newborns and adults with weakened immune systems.

“The risk assessment will be a tremendous asset in our efforts to reduce the 1,600 illnesses and 260 deaths attributed to this pathogen annually,” USDA Under Secretary for Food Safety Dr. Elisabeth Hagen said. “Essential information has been gained from these findings, including the fact that once Lm enters a retail environment, it has the potential to spread due to cross contamination. This assessment highlights the importance of our work to prevent Lm from entering the retail environment in the first place, and provides a significant tool towards this effort to protect consumers and prevent foodborne illness.”

The U.S.-focused study is the first of its kind. It quantitatively links retail deli practices to predicted public health outcomes, which has never been done before. The study is based on observations of deli employees’ work routines; concentrations of Lm on incoming products and in the deli environment; simulations of the bacteria’s transmission, such as from slicer to food; and dose-response modeling. The study was designed to apply to a range of deli establishments, from small independent operations to the deli departments in large supermarkets.

The study also reinforces the importance of FDA’s Food Code recommendations to operators of retail delis. State, local and tribal jurisdictions can do their part to reduce listeriosis by enforcing all relevant provisions of the Food Code as part of their own food safety requirements.

No single intervention will put an end to Lm in food sold at retail delis, the study found. Instead, there are many steps that retail deli operators and their suppliers can take to help reduce listeriosis. The study’s key findings include:

  • Storage temperature. If all refrigerated, ready-to-eat foods are stored at 41 degrees Fahrenheit or below, as the FDA Food Code recommends, at least 9 of every 100 cases of listeriosis caused by contaminated deli products could be prevented.
  • Growth inhibitors. If all deli products that support Lm growth were reformulated to include growth inhibitor, 96 of every 100 cases of listeriosis caused by contaminated deli products could be prevented. While this finding is significant, the actual benefit may be smaller in part because growth inhibitor may be used in concentrations not effective throughout the shelf life of a food, and it can affect the flavor.
  • Cross contamination. The predicted risk of listeriosis dramatically increases in retail delis as a result of cross contamination, with slicers remaining a particular challenge. Cross contamination is particularly difficult to eliminate, but the study shows proper cleaning and personal hygiene makes a difference.
  • Contamination of Incoming Product. If current levels of Lm in ready-to-eat foods received by the retail deli from processing establishments were reduced by half, 22 of every 100 cases of listeriosis caused by contaminated deli products could be prevented. This finding suggests that continued efforts to prevent low levels of Lm contamination during processing, even on products that do not support growth of the pathogen, reduces the risk from these products and other ready-to-eat foods that can be subsequently cross contaminated in the retail delicatessens.

FDA and FSIS have taken many steps to enhance retail food safety in an effort to reduce listeriosis and other foodborne illnesses. For instance, since its initial release in 1993, the FDA Food Code has been revised to target Lm prevention, including more stringent temperature controls for refrigerated foods and limits on how long such foods can be retained after opening or preparation.

In addition, FDA has created educational materials in recent years to support foodservice operators, including guidance on how to keep deli slicers properly cleaned and sanitized, a handbook on employee health and personal hygienefood-safety posters in nine languages, and video testimonials designed as training aids. FSIS is planning to provide outreach materials to retailers where ready-to-eat meat and poultry products are sliced, prepared, or packaged for consumption in the home. These materials will highlight risky practices based on the results of the interagency risk assessment and help retail establishments to adopt best practices that could decrease the potential for Lm growth or cross contamination.

Consumers, too, have a role to play in reducing listeriosis. For advice on keeping refrigerated foods cold, cleaning one’s refrigerator regularly, and cleaning hands and kitchen surfaces often, visit To further minimize any risk of listeriosis, FDA and FSIS recommend that older adults, pregnant women and adults with weakened immune systems reheat hot dogs and lunchmeats until steaming hot.

The study was published today and can be read in its entirety on either the FDA or FSIS web sites. A public meeting to discuss the study and its findings will be held at USDA’s Jefferson Auditorium at 1400 Independence Avenue, Southwest, Washington, D.C., on May 22nd, from 8:15 a.m. to 4:15 p.m. People who plan to attend the meeting are asked to register in advance at FSIS’ website.