Guidance for the Control of Listeria monocytogenes in Ready-to-Eat Foods

Abstract

Food contaminated with Listeria monocytogenes has the potential to cause the illness listeriosis. This can be a severe illness leading to death in vulnerable consumers. While severe cases of listeriosis are not common in New Zealand (about 25 are reported annually), the outcome of a severe infection can be significant, and 20 to 30 percent of those who become ill may die. It has been found from investigating outbreaks that the main cause of listeriosis is the consumption of RTE food that are contaminated with large numbers of L. monocytogenes. These are typically RTE foods that allow L. monocytogenes to grow, are stored at refrigeration temperatures and have a long shelf-life. Listeria unlike most of the common causes of foodborne illness can grow at the temperatures used for chilled storage i.e. below 5˚C. It is, therefore, important to identify the foods that are at risk from contamination and to establish control measures that help to minimise the potential for contamination to occur, especially for those foods that support the growth of L. monocytogenes. There has been a diverse range of foods associated with food incidents or cases of listeriosis in New Zealand. These foods include: RTE seafood, hot-smoked mussels, RTE cooked meats, hummus and/or tahini, pâté, pre-packaged salads, cooked and/or smoked chicken, vegetable dips, sandwiches, yoghurt, mussels, smoked fish and cheeses