Listeriosis - a crisis with a mystery source

Listeriosis - a crisis with a mystery source

South Africa’s listeriosis crisis has been coming on for a while - the National Institute of Communicable Diseases (NICD) has been tracking the cases for the past year, and keeping very quiet about it. 

Food and vegetables

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The numbers peaked last August, the news became public only in December, and new cases are currently being confirmed at a rate of about 10 a week.

And finally, listeriosis has been declared a notifiable disease.

There’ve been 727 cases so far - 7% or about 50 of them in KZN.

61 people have died, about 40% of them babies less than four weeks old, pregnant woman being more than 20 times more likely to get listeriosis than other healthy adults.

The death rate from listeriosis is alarmingly high - 20 to 25%, compared with salmonella or ecoli which have mortality rates of less than 1%.

Most at risk besides pregnant women are people over 65 and anyone with a compromised immune system - those with HIV/AIDS, diabetes, cancer or organ transplants.

Those with confirmed listeriosis were patients in both State and private hospitals - roughly two thirds in State hospitals and a third in private hospitals.

Of course the burning question is - where is the listeria coming from?

Sadly, the authorities still don’t know. It’s been hailed by food scientists around the world as the biggest outbreak of listeriosis ever recorded, but a year down the line, they are none the wiser as to the source.

And here’s the thing - the NICD has established via genome sequencing that in almost all cases, the listeria came form a single source. One particular product or range of products.

Pretoria-based microbiologist and food safety expert, Dr Lucia Anelich, had this to say about the food culprit: “It is most likely a product that is very widely consumed and consumed extremely often and that is why we are seeing a spike in cases. South Africa has actually had a number of cases every year, but never this alarming a rate…”

Listeriosis symptoms show up any time between two and 30 days after eating food contaminated with listeria. In pregnant women they include mild flu-like symptoms, headaches, muscle aches, fever, nausea, and vomiting. If the infection spreads to the nervous system it can cause stiff neck, disorientation, or convulsions.

So here’s the big question for consumers: what foods should we be avoiding during this listeriosis outbreak, while the authorities still no idea which widely sold and consumed product is the culprit?

Firstly, ready-to-eat foods which you don’t cook or heat (which kills the listeria organism) before eating, primarily deli meats - slices of ham, polony, cooked chicken etc, as well as refrigerated pâtés or meat spreads; unpasteurised (raw) milk and cheese made from them - not common in this country - refrigerated smoked seafood, raw sprouts and pre-packaged salads.

“Deli meats are obviously consumed by a wide variety of people in the population, whether it’s a cheaper cut or a more expensive one,” Anelich says.

"But there are likely other products that might also be just as implicated and it’s really difficult at this stage to point a finger in a specific direction, considering we have absolutely no other leads at this stage.”

And to make matters worse, can listeria carry on growing, even in a fridge.

“Listeria can grow at refrigeration temperatures, which is one of the traits of this organism that many others don’t have. So it is very important that consumers check the temperature of their fridges and keep it below 4 degrees Celcius,” Anelich says.

"The majority of our home fridges are actually not running at 4 degrees; they are often run at higher - 5, 6 and even 8 degrees. So it really important that we monitor the temperature of our fridge with a thermometer."

And there are other things we can and should do to protect ourselves from all food borne diseases - wash your hands often and ensure that we don’t contaminate cooked food with raw food or juices. So if you cut meat on board, don't put the cooked meat back onto that board or cut it with the knife you used to cut it when raw. Or take meat off a braai and put it back into the container it was in when raw.
And always keep cooked meat on a fridge shelf above raw meat so raw meat juices can’t drip on it.

I asked Anelich what advise she’d give her daughter if she were pregnant now, given the mystery source of the listeriosis.

“I would certainly advise her to avoid all the listed high risk products that are typically associated with listeria, if they can’t be cooked fully before consumption. So if she was about to make a sandwich with a slice of deli meat, and maybe some sprouts, and maybe some pre-packaged salad, I would certainly advise her not to do that.”

For more information about listeriosis in general and this outbreak in particular, go to Anelich’s website here.

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