This is despite Health Minister Aaron Motsoaledi recently announcing that the listeriosis outbreak that killed more than 180 people, and led to 1065 confirmed cases in South Africa, was officially over.
The research group’s study also revealed that the bacteria had been found in other food products that were not identified during the initial outbreak. These are ready-to-eat meat products not manufactured by Enterprise Foods and Tiger Brands.
The researchers presented the shock findings at the international conference for food safety and security in Pretoria last week.
Professor Lise Korsten, a senior researcher and co-director of the Centre of Excellence in Food Security at the University of Pretoria, said they believed that while major implicated products and brands had been removed from the shelves, some tainted products remained in the food system.
“Considering rural areas and the informal sector, it is to be expected that it is almost impossible to make sure that all contaminated food products have been effectively removed from the whole system. In addition, some of our samples show Listeria monocytogenes was present in lesser-known brands that weren’t affected by the recall,” Korsten said.
The study covered a sampling period before, during and after the listeriosis outbreak. The researchers collected 344 samples of polony between December 2016 and September this year, covering 77 brands of polony products sold by 20 food outlets in the formal and informal sector in eight of South Africa’s nine provinces.
Before the outbreak was official, out of 42 samples collected in 2016, two tested positive for the listeriosis bacteria, Korsten said. After the official announcement in December last year, 186 samples were collected, of which eight were positive.
Korsten said one of the most significant findings from the research was that once the source had been identified and products recalled, four samples from 116 samples collected as recently as last month still tested positive for listeriosis.
She said another 10 samples had subsequently been collected, but the data was not yet available.
Another finding of the study was that the listeria contamination came from the packaging of polony, rather than the ready-to-eat meat.
In her presentation Korsten also showed an image of one of the polony samples collected, with the packaging covered in meat shavings and filth.
“This raises concern around general hygiene and highlights the fact that the whole supply chain should be considered, and not just the factories from which it comes,” she said.
The head of the Centre for Enteric Diseases at the National Institute for Communicable Diseases, Dr Juno Thomas, said she was not surprised at the findings.
“The department is prioritising the development of guidelines and what levels of listeria are allowed in South Africa. In the US, there is zero tolerance on levels of listeria, but in Europe some levels of listeria are allowed. South Africa is in the process of developing those guidelines,” Thomas said.
She added that they had not detected an outbreak strain and listeriosis levels had declined in South African ready-to-eat meat.
This month Tiger Brands reopened its Germiston factory that was closed in March along with a Polokwane factory and an abattoir in Clayville after they were found to be sources of listeria.
“The fight against listeria and other food-borne pathogens is an ongoing challenge that requires the involvement and support of all parties in the supply chain. Unfortunately, such support from all stakeholders is not forthcoming, and many members of the food industry did not want to share information or allow independent product sampling once the outbreak was announced,” Korsten said.
She called for a national strategy, policy and governance to be implemented as questions around certification and auditing had resulted in a loss of trust.