The legal team behind a class action lawsuit representing more than 1 000 claimants from the listeriosis outbreak in 2017/18 say the victims have still not received any compensation, despite “breakthrough” evidence this year making an “overwhelming” case that Tiger Brands was responsible.
The listeriosis was transmitted mostly via contaminated polony, reports Daily Maverick, yet six years after the outbreak that killed more than 200 people, individuals and families who were affected have yet to receive any compensation for their suffering.
The legal team representing claimants in the lawsuit against Tiger Brands alleges that further evidence has come to light linking the infections to an Enterprise Foods factory in Polokwane, Limpopo. Tiger Brands was the parent organisation for Enterprise Foods.
The legal team is made up of Richard Spoor Incorporated (RSI) Attorneys and LHL Attorneys.
Zeenat Emmamally, an associate at RSI Attorneys, said they received two important pieces of evidence related to the outbreak from the National Health Laboratory Service (NHLS) this year.
“They confirmed that the strain predominantly responsible for the outbreak, the sequence type 6 (ST6) strain, was not found in any other facility or location apart from the facility in Polokwane,” said Emmamally.
The NHLS also provided DNA sequence data. In January 2024, the National Institute for Communicable Diseases (NICD) provided public access to sequence data via the National Centre for Biotechnology Information (NCBI) database for 403 ST6 isolates (a culture of micro-organisms isolated for study) from the outbreak.
These isolates were derived from samples collected from human patients, food products and environmental samples from the Polokwane factory, sequenced by NICD and analysed by multiple methods, including multilocus sequence typing (MLST) and core genome MLST.
Tiger Brands has had access to the sequence data since January, giving its experts the opportunity to perform independent analyses of the data, according to RSI Attorneys.
“However, Tiger Brands … has done absolutely nothing with this new evidence,” Emmamally claimed.
“These two pieces of evidence … make it an overwhelming case that Tiger Brands was responsible, not only for the ST6 cases, but for the outbreak in its entirety.”
Sequence type 6 strain
Listeriosis, an infectious disease of the blood or brain caused by Listeria bacteria, primarily affects people with impaired immune systems due to factors like pregnancy, extremes of age, underlying malignant conditions, human immunodeficiency virus (HIV) infection or chronic disease.
The species of bacteria that causes listeriosis, Listeria monocytogenes, can be broken up into different strain types. Multilocus sequence typing can be used to establish strain types, says John Besser, an independent contractor and former deputy chief of the Enteric Diseases Laboratory Branch at the Centres for Disease Control and Prevention (CDC) in the US.
When the NICD was investigating the listeriosis outbreak in South Africa, it initially included all Listeria monocytogenes infections in its case definition, which establishes the criteria used to determine who will be classified as part of the outbreak.
However, sequence typing of Listeria monocytogenes isolates from patients showed that 93% of cases had a single sequence type, ST6. The case definition was therefore refined to include ST6 cases only.
“(The NICD) used the classification strains to help them zero in on the problem. This is important because there are always a few listeria cases around even if there’s no outbreak, which might be caused by something entirely different. The sequence typing is used to group together cases that are most likely to all have the same exposure,” said Besser.
Apart from MLST, researchers further confirmed that the cases probably had a common source using core genome MLST, a globally recognised method for precisely identifying individual bacterial strains. The process showed that about 382 of the 403 ST6 isolates that were sequenced and analysed had no more than four allelic differences, meaning they were closely related and shared a common origin, said Thamsanqa Malusi, an RSI senior attorney.
Researchers tend to suspect a “common-source outbreak” when a cluster of cases shows seven or fewer allelic differences in the letters of their genetic code. There are 2.5 to 3m letters of the genetic code in listeria, said Besser.
However, a core genome MLST doesn’t look at all the letters, but rather focuses on regions of DNA shared by all strains of the species, which contain about 30% to 40% of the total genetic code. This provides a stable basis for comparison of isolates.
“Bacteria are different from people in that… they produce faster. For listeria, it can be in as little as 50 minutes, whereas for us, it takes 20 to 30 years,” said Besser.
“They’re also picking up DNA from the environment and different germs. We expect there to be some differences. But when they’re very close, as we find in this outbreak, it’s almost certain that this represents a common exposure… in all of the cases.”
Trace-back and environmental investigations
Once MLST has been used to establish a case definition for a listeriosis outbreak, the people who meet that case definition are usually interviewed to find out what they’ve eaten and where they’ve been, according to Besser.
“As we know, the trace-back investigations for polony converged on one facility.”
Besser noted that in some outbreaks, the listeriosis strain responsible for the surge in cases was not found at the facility where the contaminated food originated. This could be because the contamination was a one-time event, or because the facility was cleaned up quickly once an outbreak was detected.
In an article on the NICD-led investigation into the outbreak, published in The New England Journal of Medicine, the factory identified as the producer of the contaminated polony was referred to only as “Facility A”. It was noted that Listeria monocytogenes was isolated from 47 of the 317 environmental samples (15%) collected at Facility A.
“A total of 34 of the 47 typed isolates (72%) were identified as ST6. These isolates originated from samples collected at several facility sections (pre-cooking and post-cooking), including from food-contact surfaces, non-food contact surfaces, and chilling brine. L. monocytogenes ST6 was detected in two of 13 samples of unopened polony loaves collected at the facility,” the article stated.
It concluded that contaminated polony produced at the facility was the cause of the national listeriosis outbreak.
It was also noted that a recall of all ready-to-eat processed meat products from the facility was “associated with a rapid decline in the incidence of L. monocytogenes ST6 infections”.
“This is a classic, textbook investigation… an open-and-shut case. And once the product was recalled, the cases rapidly declined, which by itself wouldn’t be important, but given all of the other facts, is a very powerful finding,” Besser said.
‘Travesty of justice’
The Enterprise Foods factory in Polokwane has since shut down. However, RSI Attorneys claims Tiger Brands has continued to use “every legal loophole available” to delay paying compensation to the victims of the 2018 outbreak – the largest recorded in history, resulting in more than 1 000 infections and claiming 218 lives.
Those affected include children who were infected with listeriosis in utero, some of whom are still struggling with health complications like hydrocephalus and cerebral palsy.
“This case has been a travesty of justice. If there’s no immediate intervention, the condition of these victims is going to worsen,” said Malusi. “While Tiger Brands continues to make money, these children are suffering.”
Tiger Brands responds
Tiger Brands told Daily Maverick it was “saddened” by the impact the listeriosis has had and continues to have on the lives of the victims and those who lost family from the outbreak.
“We reiterate our commitment to ensuring a resolution … in the shortest possible time, in the interest of all parties, particularly the victims of listeriosis.
“Tiger Brands’ legal team and the plaintiffs’ attorneys jointly approached the NICD for access to their records … vital to a determination of the class action.”
Tiger Brands said the NICD provided the files to the plaintiffs’ attorneys in February this year.
“These were shared with the attorneys …the experts’ review of the files remains ongoing,” Tiger Brands said.
“As the lawsuit is currently pending before the Courts, Tiger Brands is not in a position to comment further.”
NEJM article – Outbreak of Listeriosis in South Africa Associated with Processed Meat (Open access)
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