Listeria monocytogenes are bacteria that live in soil, water, cattle and poultry animals in addition to thriving in poorly cleaned or designed food processing equipment. The pathogen presents unique challenges to meat and poultry processors due to its ability to proliferate in cold, refrigeration level temperatures and its resiliency to freezing temperatures as well as its natural, widespread occurrence in the environment. Even foods that have undergone a kill step can be re-contaminated by careless handling.
In late 1998/early 1999 a large outbreak of listeriosis and several recalls of ready-to-eat (RTE) meat and poultry prompted the US Dept. of Agriculture’s (USDA) Food Safety and Inspection Service (FSIS) to hold a public meeting on Feb. 10, 1999, to gather information on Listeria monocytogenes. Experts from industry groups, consumer groups, FSIS, CDC and the Food and Drug Administration (FDA) shared statistics on the subjects of foodborne illness and product contamination, as well as on-going research and research needs, testing programs, education efforts, and FSIS policy regarding L. monocytogenes in RTE meat and poultry products.
The information gathered at the February meeting led to the formulation of an action plan in the form of a series of initiatives to control Listeria monocytogenes in RTE meat and poultry products. The initiatives consisted of long- and short-term activities, interagency activities and involved all programs of FSIS. Near term initiatives included Hazard Analysis and Critical Control Points (HACCP) reassessments, guidance for the prevention of contamination by Listeria, FSIS finished product testing, consumer education and the survey of industry practices, among many other initiatives. Long-term initiatives focused on research with irradiation and agency review of products destined to vulnerable consumers (pregnant women, adults over 65, newborn infants and those with compromised immune systems) under consideration.
An outbreak of Listeria in 2002 provided important data to FSIS in the fight against the problem. The data collected, along with verification reviews and other food safety investigations, led to the conclusion that some establishments were not adequately addressing the potential for bacterial contamination in their HACCP plans, Sanitation Standard Operating Procedures (SSOPs), or other control measures.
On June 6, 2003, FSIS issued “Control of Listeria Monocytogenes in Ready-to-Eat Meat and Poultry Product; Final Rule,” outlining in detail the testing procedures, methods, requirements, alternatives, etc., for adequate programs processors needed to enact to avoid contamination.
As the initiatives and technology continued to evolve up to today, and will continue to evolve farther into the future, processors will never eradicate the Listeria monocytogenes bacteria, so controlling and limiting occurrence and contamination will be a continual battle with continual improvement possible.
Docket No: FSIS-2014-0033 from June 19, 2015, states, “Based on available data, FSIS is confident that it is successfully carrying out its mission to protect public health by enforcing safeguards designed to control Listeria monocytogenes. The Agency considers the RTE regulatory results to be an excellent indicator of the trends in pathogen presence in RTE products over several years. This downward trend shows that the interim final rule has been effective in controlling Listeria monocytogenes in RTE meat and poultry products.”
Surveillance and prevention
Federal, state and local agencies and governments all do their part to prevent listeriosis, or at least control Listeria monocytogenes. They develop and enforce regulations such as the Food Safety Modernization Act (FSMA), as well as make continual efforts to provide guidance and education to industry. Public health agencies such as CDC, FDA, National Center for Biotechnology Information (NCBI) and National Institutes of Health (NIH) work together to track cases of listeriosis in an effort to improve policies and practices and protect those who are more likely to contract listeriosis.
Listeriosis is nationally notifiable in the US. This means listeriosis infections must be reported to local, state, territorial, and federal public health authorities so they can monitor and watch for signs of an outbreak. Health agencies take the reports, and the data from them, to work on better ways to prevent the foodborne illness.
In 2004, the Foodborne Diseases Active Surveillance Network (FoodNet) piloted a surveillance system called the Listeria Initiative. It’s a nationwide surveillance system that collects information on laboratory confirmed cases of listeriosis. In 2005 almost all reporting jurisdictions and state health departments were reporting case information to the initiative.
Once a public health investigator collects case data from patients diagnosed with listeriosis, common sources are identified and compared to solve future potential outbreaks. The Listeria Initiative database gives investigators the data necessary to solve and stop outbreaks faster than in the past. In addition, molecular subtyping data from food and clinical samples of Listeria are used to identify possible related cases.
According to 2015 FoodNet data, the incidence of Listeria from 1996 to 1998 went down 45 percent. While this period was the most significant drop, incidence continued to decrease. From 2006 to 2008 incidence dropped 12 percent, and from 2012 to 2014 the decrease was 5 percent.
Starting in 2013, laboratories across the country began following Listeria samples through whole genome sequencing (for more information read “Food Safety Fingerprinting” in the Jan. 2018 issue of MEAT+POULTRY), a process allowing health officials to create a “fingerprint” of individual bacterium through its complete DNA sequence.
Oct. 23- 24, 2018, in Kansas City, Missouri, the North American Meat Institute (NAMI) will hold its annual “Advanced Listeria monocytogenes Intervention and Control Workshop” to help meat industry processors stay up to date on regulatory issues and changes. The workshop features presentations on the latest developments in Listeria control, hands on demonstrations, breakout sessions, and case studies with experienced industry professionals. Workshops like these and whole genome sequencing are just a few of the many ways for processors to keep up the fight against foodborne illnesses caused by Listeria monocytogenes.