On the 12th December I wrote a blog titled Listeria: what you need to know. At the time of writing, 557 cases of Listeriosis had been reported, and there had been 36 reported fatalities. Even then that was deemed to be an exceptionally high number of fatalities.
On the 4th March Health Minister Aaron Motsoaledi announced that polony and other ready to eat (RTE) products from an Enterprise Foods factory in Polokwane‚ Limpopo‚ were the source of the world’s largest outbreak of listeria. In his statement, the Health Minister said that this particular strain of Listeria monocytogenes was particularly “virulent”. The Minister advised the public to “avoid all processed meat products that are sold as ready to eat” and said that “the National Consumer Commission has issued the manufacturer involved with food recall notices”.
Later in March the World Health Organisation confirmed that South Africa’s Listeria outbreak is the largest ever recorded globally, and as of the 29th of March the official death toll stood at 189 and is expected to rise further due to the long incubation period of the disease. A total of 982 laboratory-confirmed listeriosis cases (from all provinces across SA) have now been reported to the NICD since January 1, 2017, and this too is expected to rise over the coming months.
I was fortunate enough to be able to attend a workshop hosted by Food Focus in partnership with Entecom last week, titled “Preventing Listeria: practical insights and solutions”. Whilst the workshop was aimed primarily at the food manufacturing industry, I left with some very valuable insights into Listeria as an illness, the challenges it poses to food producers, and the role that hygiene plays in controlling Listeria.
Some takeaways from the workshop:
Whilst there was a wealth of information shared at the workshop - and my apologies in advance to the speakers for condensing down their detailed and insightful presentations - these were some of the points that really hit home with regard to how we look at this outbreak, and what it means for food safety in South Africa in the future:
Firstly; that cases of Listeria monocytogenes are actually relatively rare compared to cases of Salmonella (which is the leading cause of foodborne disease in humans worldwide), but that Listeria has a much higher mortality rate; around 30%, compared to an overall mortality rate of under 1% for Salmonella.
It is also found in relatively high frequency on many different foodstuffs, but at low levels, where it poses little risk to the consumer. So whilst Listeria monocytogenes causes a severe disease with a high mortality rate, exposure to high levels of the bacteria are required to actually contract the disease.
Secondly, that Listeria monocytogenes is extremely hardy; it can survive both freezing, drying, and high levels of salt, and its ability to form a protective biofilm means that it is extremely hard to kill. It is however killed by pasteurisation (of milk) and thorough cooking of raw meats.
And the third point - and the one that should really make hygiene practitioners sit up and take note - was Listeria monocytogenes’ persistence! The bacteria can become established in niches (hard to clean surfaces or locations) within food production facilities despite correct and frequent cleaning and disinfection, and it can remain on surfaces or equipment for several months to years! Because of this, Listeria is a universal problem for food manufacturers, and even when all reasonable hygiene measures have been put in place, problems can still arise.
So what does this mean for food manufacturers and hygiene practitioners going forward?
My overwhelming feeling after leaving the workshop was that there really is no silver bullet against Listeria monocytogenes. No doubt food producers wish there was a quick solution, but if you consider the nature of the bacteria - its’ hardiness and its’ persistence - you start to realise that any attempt to control it needs to be a fully integrated food safety strategy that takes into consideration every single touch point - human and machine - in the food processing space, and even after the product leaves the factory.
Before Listeria monocytogenes can be controlled in a food processing environment, it needs to be eliminated from harborage points like drains, and those niche locations. A thorough cleaning and sanitation program for the entire facility has to be the first step in a carefully constructed end to end food safety plan. Drains are frequently contaminated with Listeria monocytogenes and should therefore receive special attention; the biofilm that the bacteria creates needs to be eliminated first using specialised cleaning products, followed by sanitising or disinfecting to eliminate the bacteria.
There are SO many ways Listeria can move from a non-food surface (like a floor drain) to food contact surfaces, including - but certainly not limited to - employees’ clothing, hands, and gloves, as well as via pests such as flies and cockroaches which thrive in unclean drains. These insects carry diseases and can spread bacteria from one area to another as they move about a food manufacturing facility. Along with cleaning and disinfecting, pest control MUST also form an integral part of any food safety and hygiene strategy.
Good personal hygiene and clean working practices are also a critical piece in any food safety strategy, with an emphasis on personal protective equipment, hand sanitisation and footwear cleaning, as is creating a culture in which food safety standards are non-negotiable for employees.
And so back to the question I posed in the title, the question that everyone is asking; could this outbreak have been prevented? I’m not a doctor, a food scientist, or a microbiologist, and this is simply my opinion, but based on what I heard at the workshop last week, it feels like the answer is two-fold.
Based on the prevalence of the Listeria monocytogenes bacteria and the difficulty food manufacturers worldwide have in eliminating it completely, I think the answer has to be no, we were bound to have an outbreak of some sort at some stage (please note I’m not saying it’s acceptable).
But perhaps what was not inevitable was the severity of the outbreak and the number of deaths that have resulted from it. Had food manufacturers handled the situation differently - for example by stopping production immediately, issuing a voluntary recall of all at risk products (instead of waiting for a forced recall by the National Consumer Commission), doing testing for Listeria monocytogenes in their products - we may have seen fewer cases and fewer deaths.
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