Between January 2017 to 24 April 2018, 1,024 laboratory-confirmed listeriosis cases were reported to the National Institute for Communicable Diseases (NICD).
Outcome of illness is known for 700 patients and 200 have died.
Whole genome sequencing on 521 isolates from patients revealed 85% of the strains belonged to L. monocytogenes Sequence Type 6 (ST6).
Eighty tons of recalled items destroyed per day
The ST6 sequence type was identified in a widely consumed ready-to-eat processed meat product called “Polony”.
It was also found in the processing environment of Enterprise Foods, a division of Tiger Consumer Brands, which manufactured the implicated product.
In March, the Ministry of Health made a country wide recall of implicated products and since an additional 55 illnesses have been reported.
Since early March, cases per week have dropped to fewer than 15 per week. At the height of the outbreak, 30 or more were noted weekly.
Post recall out of 27 interviews with people diagnosed with listeriosis 17 ill people reported consuming or handling polony prior to illness onset.
Affected products are being warehoused and destroyed at a rate of 80 tons per day.
Independent tests confirm outbreak strain
Independent laboratory tests by Tiger Brands confirmed the strain in a sample of RTE processed meat product from its Polokwane facility.
CEO Lawrence Mac Dougall said it was ‘enormously disappointed’.
“We are making every effort to ascertain how ST6 arrived in a product manufactured in our production facility in Polokwane, despite us adhering strictly to all the prevailing industry standards,” he said.
“The Listeriosis outbreak has been a terrible blight on the entire ready-to-eat meat industry. It is imperative for the entire industry come together to agree on appropriate standards with government. It is not a problem which is unique to South Africa or for that matter to Enterprise Foods.”
The Democratic Alliance party welcomed the decision to keep the plant closed whilst remedial work was done but expressed concern that it was not known how factories were contaminated.
“The reality is that there has been a lack of political will and clarity on the part of Minister Motsoaledi to get to the bottom of the Listeriosis outbreak. This outbreak points to a broader neglect of proper food safety mechanisms on the part of the government,” said the political opposition.
A food safety team including WHO, national, provincial and district experts will visit Tiger Brands and RCL production facilities this week.
Tests on environmental samples from RCL Foods’ Wolwehoek facility found L. monocytogenes but whole genome sequencing showed it was not the outbreak strain.
Enterprise Foods and three of its retailers export to 15 countries in the African region.
Thirteen of these countries have recalled products implicated in the outbreak and banned such imports. Two have banned imports of other food products not directly linked to the outbreak.
The confirmed case of listeriosis in Namibia has been sequenced and belongs to a different type so is not linked to the outbreak in South Africa.
WGS analysis of isolates from patients found 15% represented 19 other types (ST1, ST54, ST876, ST2, ST5, ST204, ST219, ST224, ST71, ST101, ST121, ST155, ST3, ST403, ST515, ST7, ST8 and ST88).
WHO added as some genotyped samples did not match the outbreak strain it was essential to strengthen sequencing capacity to monitor the outbreak.
WGS on 595 food and environmental isolates at NICD identified 13% (79/595) as ST6.
Other isolates represent 26 sequence types: 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.