'Breakthrough' listeriosis evidence unpacked

Six years on from the listeriosis outbreak in South Africa that killed more than 200, individuals and families who were affected by the outbreak have yet to receive any compensation for their suffering. The legal team representing claimants in a class action lawsuit against food producer Tiger Brands alleges that ‘breakthrough’ evidence has come to light, further linking the surge in listeriosis infections to an Enterprise Foods factory in Polokwane. The Daily Maverick reports that 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. ‘We’ve received confirmation from them that the strain that was predominantly responsible for the outbreak, the sequence type six (ST6) strain, was not found in any other facility or location apart from Tiger Brands’ Enterprise facility in Polokwane,’ said Emmamally.

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 listeriosis outbreak. DM reports that these isolates were derived from samples collected from human patients, food products and environmental samples from the factory in Polokwane, sequenced by NICD and analysed by multiple methods, including multilocus sequence typing (MLST) and core genome MLST. RSI Attorneys says Tiger Brands has had access to the sequence data since January, giving its experts the opportunity to perform independent analyses of the data. However, ‘Tiger Brands … have done absolutely nothing with this new evidence,’ Emmamally claimed. ‘These two pieces of evidence in conjunction make it a very overwhelming case that Tiger Brands was responsible, not only for the ST6 cases, but for the outbreak in its entirety.’

In a journal article on the NICD-led investigation into the listeriosis 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 (precooking and postcooking), 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. DM notes that it concluded that contaminated polony produced at the facility was the cause of the national outbreak of listeriosis.