One of the biggest food safety news stories in South Africa, never has there been such a big news break than today (5 December 2017).
There were 570 confirmed cases of Listeriosis, including 36 deaths thus far. Cases were confirmed in Gauteng, Western Cape and KZN. Further details have unfortunately not been forth coming, and one can only assume that the investigation is still under way.
The health department at the current stage, has not been able to identify the source of the outbreak because of the incubation time (ranging from 3 – 70 days) to present symptoms of Listeria induced food poisoning, and the rarity of the infection.
What is Listeriosis?
A food-borne illness primarily caused by a bacterium called Listeria monocytogenes. You will likely here that L.monocytogenes is an environmental pathogen that occurs virtually throughout the environment : soil, water, animals etc. So not really useful information, as L.monocytogenes is usually only a problem when it comes to food.
Mild symptoms much like other food poisoning symptoms, typically causes gastroenteritis meaning fever and diarrhoea.
Severe symptoms can infect other parts of the body : Fever, stiff neck, confusion, weakness, vomiting, sometimes preceded by diarrhoea.
Those at most risk
- Pregnant women
- Elderly (+65 years)
- Low immune system
More about Listeria monocytogenes
L.monocytogenes is in some ways a super germ, in that is can grow and survive at cold temperatures up to 0°C (32°F), meaning L.monocytogenes will grow in your fridge. However, this germ can be killed by relatively low heat from 50°C (122°F) versus E.coli which needs +65°C (149°F) to be killed.
This seems like a relief right? Just cook your food, and done. Right? Unfortunately not…
Foods affected by Listeria monocytogenes
- Pre-packed salads (salad items)
- Smoked seafood
- Soft cheeses
- Deli meats & Viennas
- Raw milk and other dairies
- Certain vegetables
- Raw chicken!
Traditionally foods that are not cooked or reheated, except in the case of raw chicken and viennas. Most cases worldwide come from manufacturing and processing, after cooking has occurred, telling us that cross-contamination is the main culprit.
In the commerical kitchen, L.monocytogenes is often found in the floor drains and cooling units of fridges and cold rooms. At home ensuring the basin drains are regularly cleaned and disinfected is essential.
Recommendations for prevention
Most of the recommendations for preventing Listeriosis is to either avoid these foods and heat them to above 50°C (122°F). In most cases virtually impossible to do. Especially because, as a pathogen, there are no signs that this bacterium is present in your food.
Further recommendations made by the health department suggest that you should wash your hands before and after food preparation, which is good advice, but not the ultimate preventative measure.
As microbiologists and food safety consultants, we can only give general ‘best practice’ advice for food poisoning preventions, ie The food safety pillars.
- Ensure good cleaning and sanitising of counter tops, tables, cutting boards, equipment.
- Good and frequent hand washing and personal hygiene.
- Proper food storage practices, separating raw and ready to eat foods.
- Ensuring proper cooking / refrigeration
- Preparing food groups separately, not leaving foods out unnecessarily.
- Clean out floor drains and cooling units of fridges and cold rooms.
- Ensure that basin drains are cleaned and disinfected regularly.
Follow the Listeriosis timeline below:
We have an updated post on the outbreak here!
For more information on the food safety pillars check the ebook on Amazon.
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