Listeriosis Risk In Frozen Vegetables
The Food Standards Agency (FSA) has issued a warning following a Europe-wide listeriosis outbreak that has been linked to frozen vegetables. This follows an investigation by the European Food Safety Authority (EFSA) into the deaths of nine people in five countries since June 2015 which confirmed that the deaths were caused by Listeria monocytogenes. The five countries affected are the UK, Austria, Denmark, Finland and Sweden. The outbreak has been linked to a Hungarian plant and a recall has been issued on all frozen vegetable products which were produced there.
Fiona Sinclair is director at leading UK food safety consultancy STS. She says: “Although there is limited information available about this outbreak, listeria monocytogenes is a bacterium which is commonly found in dust, dirt and soil so it can be present on raw vegetables. While thorough cooking would ordinarily destroy the bacteria, it is possible that consumers consumed the produce cold or without thorough cooking, contrary to manufacturer’s advice. This could lead to illness if the bacteria were present and consumed.
“As this outbreak appears to have occurred over a prolonged time frame, it could be due to the presence of biofilms in the production environment. Biofilms are where the bacteria form a protective layer on a surface; if food then comes into contact with this surface, contamination can occur. Biofilms are stubborn and can be difficult to eliminate from a food production environment as they’re often resistant to the usual cleaning process i.e. chemicals and methods of cleaning. If persistent biofilms are found in a manufacturing environment, this can be another potential source of food contamination.
“Listeriosis has an unusually long incubation time compared to other food borne illnesses; it can be up to 90 days between consuming the contaminated food and developing symptoms. This means that it can be difficult to identify the source of illness sometimes, and often it’s only established through epidemiological data, as in this case, particularly when an outbreak is on an international scale.
“Although listeriosis is relatively rare, the fatality rate is around 30%, which is why it is so dangerous. Listeriosis actually kills more people than any other food-related illness here in the UK, with the elderly and immuno-compromised being particularly vulnerable to infection.
“The FSA’s warning in this case only reiterates the message to always follow the manufacturer’s instructions i.e. to cook food thoroughly unless it is specifically labelled ready to eat. This outbreak shows that this manufacturer’s advice is there for good reason rather than just to fill space on packaging.”