Listeria contamination and controls – 20/05/10
Listeria monocytogenes is a bacteria that can cause the severe and sometimes life threatening food borne illness known as listeriosis. This is primarily of concern for vulnerable groups such as people over 60, people with a weakened immune system, pregnant women and new born babies. It can take from 1 to 90 days from consumption of Listeria contaminated food for the illness to develop. The illness causes a range of symptoms including mild eye and skin infections, flu-like symptoms, gastroenteritis and in more severe cases can cause septicaemia (blood poisoning), miscarriage, meningitis and even death in the most vulnerable patients.
Legislation
There are specific requirements on Listeria in the legislation; "Food business operators manufacturing ready-to-eat foods, which may pose a Listeria monocytogenes risk for public health, shall sample the processing areas and equipment for Listeria monocytogenes as part of their sampling scheme". Ref: Regulation 2073 / 2005 on microbiological criteria of foodstuffs, Article 5. This regulation also sets limits for Listeria in ready to eat foods.
European Alerts related to Listeria
In recent years there has been an increase in the numbers of the RASFF (Rapid Alert System for Food and Feed) alerts linked to food contaminated with Listeria monocytogenes. The figures available on the RASFF website show 77 alerts due to Listeria contaminated food products in 2009. This is significantly higher than 48, the number of alerts linked to Listeria contaminated products in 2008 and 35 in 2007.
Where is it found?
Listeria is present naturally within the environment. This can include being found in raw food, soil, vegetation, sewage, and the faeces of animals, birds, and fish.
People are usually infected after eating Listeria contaminated food. These typically include ready to eat chilled foods such as sandwiches, salads, cooked meats, smoked salmon, soft cheese and pâté. Unlike most other bacteria, Listeria can survive and grow at refrigeration temperatures 0 - 5˚C. However the risk is eliminated in foods that are properly heated prior to consumption or in the case of dairy products, Listeria is eliminated by effective pasteurisation.
How is food contaminated?
- Incorrect storage temperature, i.e. Listeria can grow at refrigeration temperatures and can survive below 0oC.
- Contamination from the factory itself, i.e. poor personal hygiene practices and poor cleaning practices can lead to a build up of Listeria within equipment.
- Using ‘out of date' ingredients for a ready to eat product.
- Buying raw materials from non-approved suppliers.
- Eating food past its ‘use by date'.
How to reduce the likelihood of Listeria contamination in the food factory?
- Ensure staff are trained in food hygiene practices
- Have good cleaning procedures in place to ensure all equipment is cleaned and disinfected
- Carry out random swab testing to check for the presence of Listeria within the factory and also analyse products for Listeria levels.
- Ensure that refrigerators and chillers are working correctly.
- Ensure the HACCP plan effectively controls the risk of Listeria contamination
- Ensure you have an effective internal auditing process
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