The deadly South African listeriosis outbreak has a high 28.6% fatality rate, according to a report by the National Listeria Incident Management Team (IMT). The IMT report says 200 of 1,024 confirmed cases of listeria resulted in the deaths of the victims. The outbreak is slowing down, but, says a Food Safety News report, it’s not over. The National Institute for Communicable Diseases (NICD) has logged 55 new cases in the seven weeks after the source of the outbreak was announced on 4 March. That’s when Minister of Health Dr Aaron Motsoaledi named ready-to-eat processed meat products from the Enterprise Foods’ production facility in Polokwane as the source of the Listeria monocytogenes and initiated recalls.
In the seven weeks prior the 4 March actions, 169 confirmed cases were added to the outbreak.
The report says Motsoaledi declared the current outbreak last December after South Africa experienced a sharp increase the number of listeriosis cases from an average of 60-to-80 cases a year. The 1,024 confirmed cases of listeriosis with 200 deaths have occurred between Jan. 1, 2017 and April 24. 2018.
Neonates, less than 28 days, is the most affected age group, followed by adults aged 15 – 49 years of age. Gauteng Province reports 59% of the cases or 601 out of 1,024 cases. The Western Cape accounts for 128 cases or about 13% of the total with KwaZulu-Natal province reporting 7% or 73 cases.
The report quotes the IMT report as saying that the whole-genome sequencing analysis was used on 521 clinical isolates to date. Of these, 85% or 443 of the 521 contained the sequence type ST6.
The remaining isolates contained 19 sequence types, including ST1, ST54, ST876, ST2, ST5, ST204, ST219. ST224, ST71, ST101, ST121, ST155, ST3, ST403, ST515, ST7, ST8, and ST88. This group accounts for 15 percent of the total or 83 out of the 521 cases.
Whole genome sequencing, performed on 595 food and environmental isolates – of these, 13% (79/595) were identified as ST6. The remaining strains (87%, 516/595) represented 26 sequence types, including ST20, ST1, ST121, ST5. ST321, ST9, ST155, ST2, ST3, ST87, ST120, ST378, ST101, ST108, ST2288, ST31, ST7, ST11, ST122, ST14, ST37, ST4, ST54, ST76, and ST88.
The report says the first phase of South Africa’s listeriosis emergency response plan (ERP) is complete. It shared the response plan with provincial stakeholders, environmental health practitioners, communicable disease coordinators and others. Phase Two includes on-site visits to Tiger Brands and RCL facilities for training and inspection activities.
Also, South Africa’s National Consumer Commission (NCC) and Department of Environmental Affairs (DEA) are jointly managing recalls of various brands of ready-to-eat meats. The two agencies are destroying about 80 tons of ready-to-eat meat products each day.
The report of the rising death toll in the listeriosis outbreak follows Tiger Brand’s disclosure to its shareholders that company-sponsored testing also found ST6, the outbreak strain, in its facilities.
Such disclosures usually come later in the discovery process or by subpoena, but, the report says, Tiger Brands choose not to wait. The most significant food company in South Africa, Tiger Brands is also the defendant in litigation brought against it on behalf of listeriosis victims and their survivors.
Of the almost 600 Listeria-positive samples from food products and food processing plants which the NICD has performed its “DNA fingerprinting” on‚ only 13% were the outbreak strain ST6. And, reports The Times, all of those were linked to Tiger Brands’ Enterprise brand; both their products – including the polony found in the fridge of the Soweto creche – and their Polokwane plant‚ says the NICD’s Dr Juno Thomas. “The other samples contained a total of 26 different strains of listeria.”
The “listeria hysteria”, which has gripped the country in the two months since government revealed that the source of the world’s worst listeriosis outbreak was that Enterprise factory‚ has seen the food industry embark on a frenzy of testing for the deadly food-borne bacteria in their factories.
The report says state and private laboratories are able to identify listeria in a sample‚ but the NICD is the only organisation in the country with the technology to conduct whole genome sequencing (WGS) in order to reveal the specific strain of listeria. The food samples being sent for testing by the NICD aren’t just high-risk ready-to-eat processed meat such as polony‚ ham and viennas. “We’ve had dairy products‚ raw chicken and meat – all kinds of foods‚” Thomas said.
While food products which consumers heat or cook before eating are considered to be low risk‚ because listeria is killed by heat‚ they could contaminate ready-to-eat foods such as dairy products or vegetables in a consumer’s fridge.
The NICD’s latest report on South Africa’s devastating listeriosis outbreak puts the number of confirmed cases at 1024‚ and deaths at 200. WGS analysis of 521 samples from people who have contracted listeriosis since last January has revealed that 85% had the outbreak strain of ST6.
That the remaining 15% comprised other strains of listeria was not surprising or concerning‚ Thomas said‚ as having 60 to 80 “background” cases of listeriosis was normal‚ and the slightly higher number of non-outbreak strain cases was to be expected given the now heightened awareness around listeria‚ along with increased testing.
“In the past‚ there would have been no testing done on unexplained miscarriages and stillborn babies‚ for example‚” she said.
The report says NICD officials have interviewed 27 people – or their family members – who fell ill with listeriosis after the recall‚ asking them what they ate in the period leading up to them getting the first symptoms – only 63% of them said they ate or handled polony.
“There are many possible reasons for that‚” Thomas said. “Some would have been infected by non-outbreak strains‚ and a family member may not have known that the person who fell ill bought a polony ‘kota’ on the way to work.”
Someone who ate contaminated polony on the day of the recall could still fall ill‚ given that listeriosis’ incubation period is up to 70 days. It’s also possible that news of the recall didn’t reach every household in the country‚ and given the long shelf-life of a product such as polony‚ the implicated products could still be being consumed.
The report says Bill Marler – a US attorney who has dealt with hundreds of food-borne pathogen outbreaks around the world in the past 25 years – predicted in March that the final numbers would be 2,000 cases and 400 deaths.