In early 2017, hospitals across South Africa began noticing an alarming trend. More and more patients were arriving with severe infections, particularly newborns and pregnant women. What started as isolated cases would soon become the largest listeriosis outbreak ever recorded globally, claiming over 200 lives and exposing critical weaknesses in food safety systems that would force a complete rethinking of how ready-to-eat foods are regulated and monitored.
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The scale of the crisis
Between January 2017 and July 2018, South Africa documented 1,060 laboratory-confirmed cases of listeriosis, with 216 deaths reported. To put this in perspective, South Africa typically saw only 60 to 80 cases annually in previous years. The outbreak peaked in December 2017, when health officials were recording 32 new cases per week.
The human toll was devastating. Nearly half of the victims were neonates, babies 28 days old or younger, who contracted the infection during pregnancy or delivery. The outbreak particularly affected low-income communities where processed meats like polony were dietary staples due to their affordability and convenience.
Understanding listeriosis
Listeriosis is caused by the bacterium Listeria monocytogenes, which poses unique challenges for food safety. Unlike most foodborne pathogens, Listeria can grow at refrigeration temperatures as low as 0°C, making refrigerated ready-to-eat foods particularly vulnerable to contamination. The disease is especially dangerous for pregnant women, newborns, elderly individuals, and people with weakened immune systems.
The outbreak strain was identified as Sequence Type 6 (ST6) through advanced genetic testing. This particular strain has been associated with several international outbreaks and is known to cause severe disease outcomes.
How the outbreak unfolded
The first warning signs appeared in July 2017 when doctors at Chris Hani Baragwanath Hospital in Soweto noticed an unusual spike in listeriosis cases. By December 2017, the pattern was unmistakable. The National Institute for Communicable Diseases confirmed an outbreak, with cases spreading across all nine provinces of South Africa.
For months, health officials struggled to identify the source. The breakthrough came in mid-January 2018 when nine children from a Soweto crèche fell ill. Investigators tested polony samples from the childcare facility and found they were contaminated with the outbreak strain. This discovery led them directly to the production facilities.
The source identified
On March 4, 2018, Health Minister Aaron Motsoaledi announced that the outbreak was traced to the Enterprise Foods facility in Polokwane, owned by Tiger Brands, one of Africa’s largest food manufacturers. Environmental sampling of the facility revealed extensive contamination, with 34 out of 47 positive samples identified as the ST6 outbreak strain.
The contaminated product was polony, a popular South African processed meat similar to bologna. What made the discovery particularly troubling was that inspections of all 157 ready-to-eat meat production facilities in South Africa found the ST6 strain only at Tiger Brands’ Enterprise facility.
The power of whole-genome sequencing
This outbreak marked a turning point in how foodborne disease outbreaks are investigated. Scientists used whole-genome sequencing to analyze bacterial isolates from patients, contaminated food products, and the factory environment. Ninety-one percent of clinical isolates belonged to the ST6 sequence type, providing conclusive evidence linking the illnesses to a single source.
The genetic analysis revealed something even more concerning. The outbreak strain showed less than 10 genetic differences between isolates from patients, food products, and the factory environment, indicating they were virtually identical. This level of precision allowed investigators to trace the contamination with certainty previously impossible with older testing methods.
Government response and immediate action
Once the source was identified, authorities moved swiftly. Tiger Brands was ordered to recall all ready-to-eat processed meat products from its Enterprise facilities. The Polokwane plant was immediately closed, along with two other Tiger Brands facilities that showed signs of contamination.
The recall was massive in scale. Over 5,800 tons of affected foodstuffs were recalled and destroyed. The products had been exported to 15 countries across Africa, prompting international recalls and temporary import bans from neighboring nations.
Within weeks of the recall, new cases plummeted. By June 2018, the number of new infections had dropped to pre-outbreak levels. In September 2018, the outbreak was officially declared over.
Systemic failures exposed
The investigation revealed troubling gaps in South Africa’s food safety system. The Enterprise facility had inadequate environmental monitoring programs, failing to detect persistent Listeria contamination in the production environment. Product testing protocols were insufficient to catch contaminated batches before distribution.
More broadly, the outbreak exposed fragmented regulatory oversight, with food safety responsibilities scattered across multiple government departments without adequate coordination. South Africa also lacked the inspection capacity needed to adequately monitor food production facilities, and existing regulations hadn’t kept pace with international best practices for ready-to-eat foods.
Regulatory transformation
The outbreak catalyzed comprehensive reforms in South Africa’s food safety system. Listeriosis was made a notifiable disease, requiring mandatory reporting of all cases. New regulations published in June 2018 required all facilities producing ready-to-eat processed meat and chicken to have food safety management systems in place, including mandatory HACCP certification.
Nearly 900 environmental health practitioners were retrained in factory inspections, food safety systems, and Listeria testing protocols. A national surveillance system was established to identify and sequence all Listeria isolates from human cases, enabling faster detection of future outbreaks.
Industry transformation
The processed meat industry underwent significant changes beyond regulatory compliance. Companies increased transparency by publishing food safety audit results and testing data. Many adopted advanced detection methods and improved traceability systems. Perhaps most importantly, food safety shifted from being viewed as merely a compliance issue to a core business value.
Lessons for global food safety
The South African outbreak offers crucial lessons for food safety systems worldwide. It demonstrated the critical importance of environmental monitoring in food processing facilities, as persistent contamination in production environments can lead to repeated product contamination even after cooking processes.
The outbreak also highlighted the value of whole-genome sequencing technology in outbreak investigations. This precision allowed investigators to definitively link cases to their source and distinguish outbreak cases from sporadic infections, something that would have been impossible with traditional testing methods.
Finally, the crisis underscored the need for integrated surveillance systems that combine laboratory data with epidemiological investigations. The eight-month delay in identifying the source demonstrated that even sophisticated testing capabilities require coordinated investigation efforts.
Ongoing accountability
More than six years after the outbreak, legal proceedings continue. In December 2018, a class-action lawsuit was certified, allowing around 1,000 claimants to seek compensation from Tiger Brands. The case highlights the complex challenges in establishing legal liability for foodborne illness outbreaks, particularly when proving direct causation between specific products and individual illnesses.
What do you think? How can food manufacturers balance the economic pressures of production with the absolute necessity of maintaining rigorous safety standards? What role should consumers play in holding food companies accountable beyond just their purchasing choices?
References
- https://www.who.int/emergencies/disease-outbreak-news/item/28-march-2018-listeriosis-south-africa-en
- https://pmc.ncbi.nlm.nih.gov/articles/PMC6653791/
- https://www.nejm.org/doi/full/10.1056/NEJMoa1907462
- https://www.foodsafetynews.com/2024/09/publishers-platform-more-than-six-years-after-the-largest-listeria-outbreak-victims-have-still-not-been-compensated/
- https://www.gov.za/news/media-statements/minister-aaron-motsoaledi-listeriosis-outbreak-03-sep-2018
- https://www.foodsafetynews.com/2018/09/south-africa-declares-end-to-largest-ever-listeria-outbreak/
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