1 Messages relating to contamination of Listeria monocytogenes
①On May 15, 2020, the European Union Food and Feed Rapid Early Warning System (RASFF) issued reference number 2020.2046. France notified RASFF that its goat cheese balls filled with honey may be potentially contaminated with Listeria monocytogenes. It is reported that the substandard products have been distributed to other member countries.
②On April 20, 2020, according to European Food Safety Authority, a multi-country outbreak of Listeria monocytogenes ST6 linked to blanched frozen vegetables took place in the EU (2015-2018).
③On May 15, 2020, according to U.S. Food and Drug Administration, Ramar Foods of Pittsburg, CA, is recalling its 14 ounce packages of Peekaboo branded Mint Chocolate Chip with Hidden Spinach Ice Cream product out of an abundance of caution because of the potential contamination of Listeria monocytogenes.
The above short messages are all related to contamination of Listeria monocytogenes. Why do regulators and consumers need to pay attention to Listeria monocytogenes in food? This article will introduce its origin, susceptible population, hazards and regulatory requirements, and give suggestions on how to prevent infection of Listeria monocytogenes.
2 What is Listeria monocytogenes？
Listeria monocytogenes, motile, gram-positive rod, is a foodborne pathogen capable of causing listeriosis in humans. L. monocytogenes is resistant to freezing, drying, and heat. It is widely distributed in nature, which can be found in soil, water, vegetation, sewage, silage, and can survive in the intestinal tract of various animals. Additionally, 0.1 to 10 cases out of per 1 million people might infected by Listeria monocytogenes per year depending on the countries and regions of the world. Although the number of cases of listeriosis is small, the high rate of death makes it a major public health concern threatening people’s health.
3 Origin of Listeria monocytogenes in food
The most common food associated with listeriosis include foods with a long shelf-life under refrigeration and foods that are consumed without further treatment. In past outbreaks, foods mainly included ready-to-eat meat products, such as sausages and smoked salmon, as well as dairy products (including soft cheeses, unpasteurized milk) and fresh vegetables and fruits etc. In addition, L. monocytogenes also can contaminate food-processing environments, posing a threat to food chain. It can multiply in most ready-to-eat food and is often taken into ready-to-eat food through incidental contact with contaminated surfaces.
4Susceptible and harmful of Listeria monocytogenes
There are two main forms of illness associated with L. monocytogenes infection: noninvasive and invasive listeriosis.
Noninvasive listeriosis is a mild disease mainly affecting healthy people. Symptoms include diarrhea, fever, headache and muscle pain. The incubation period is short (a few days).
Invasive listeriosis is more severe and affects certain high risk groups of the population. Infants, elderly people and people with low immunity infected by listeriosis may experience serious complications such as septicemia and meningitis, and even death. Pregnant women infected by listeriosis can cause miscarriage, premature death, premature delivery, or severe infections in newborn babies. The incubation period is usually one to two weeks but can vary between a few days and up to 90 days.
5 Relevant standards or regulations of major countries and regions
a. unless there is scientific evidence that L. monocytogenes is not easy to grow in the food under refrigeration, this criterion applies to all refrigerated foods (except condensed foods). Category 1 ：RTE foods in which growth of L. monocytogenes can occur Category 2A：RTE food products in which limit growth of L. monocytogenes to levels not greater than 100 CFU/g can occur throughout the stated shelf-life Category 2B：RTE food products in which the growth of L. monocytogenes cannot occur throughout the expected shelf-life of that food
6 Suggestions for preventing infection of Listeria monocytogenes.
Many preventative measures can be taken to avoid infection with L. monocytogenes. Suggestions on three levels of regulatory authorities, manufacturing enterprises and consumers are below.
①Regulatory authorities should strengthen regulatory standards, focused attention on the need to control this threat to food safety in the processing environment. In addition, educating consumers, especially those in high risk groups, and training food handlers in safe food handling are indispensable.
②Food manufacturing enterprises should control L. monocytogenes in food by monitoring the food processing environment. It is suggested that the HACCP system should be used to strictly control the entire production process, establish good manufacturing practices (GMP) and hygienic practices (GHP), as well as analyze and control the key points of HACCP in detail, so as to reduce the possibility of product contamination by L. monocytogenes.
③Consumers should maintain good food and personal hygiene. Those at high risk for listeriosis can avoid eating the following foods: hot dogs, soft cheeses, unpasteurized products, refrigerated meat spreads and refrigerated smoked seafood etc.
Please note: Original English article of Business Division of Food Safety and Regulatory Compliance of Global Foodmate, please indicate the source from the Global Foodmate if reprint.
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