The agency said it refutes the notion that the source is not clear and that Minister of Health Aaron Motsoaledi ‘backed down’ on the previous announcement of it being traced to a ready to eat processed meat product called ‘polony’.
Listeria monocytogenes strain type 6 (ST6) was isolated from polony made by Enterprise (a division of Tiger Brands) and environmental samples at a production plant. ST6 matches most clinical isolates from patients.
NICD added it was ‘extremely misleading’ to claim the primary cause of the listeriosis outbreak was unknown.
DA: Premature scapegoating
The Democratic Alliance had said although Listeria monocytogenes was found at Enterprise and Rainbow Chicken (RCL Foods) plants, they were not primary sources of the outbreak.
“It is now apparent that the government seems to be blaming bureaucratic processes and has opted for prematurely scapegoating Enterprise and Rainbow because it does not have proper emergency plans in place to contain this outbreak,” said the country’s main opposition political party.
The Departments of Health (DoH); Trade and Industry (DTI) and Agriculture, Forestry and Fisheries (DAFF) briefed Parliament on the outbreak last week (Wednesday).
NICD said statements by Motsoaledi were based on its epidemiologic and scientific investigations.
“The implication that the NICD has misled the Minister of Health and the public is rejected. Furthermore, we condemn the statement made that the government prematurely scapegoated ‘Enterprise and Rainbow’ without sufficient evidence. We contend that this evidence has been amply provided by the NICD.”
Almost 1,000 laboratory-confirmed listeriosis cases have been reported to NICD since January 2017. Outcome of illness is known for 687 patients of whom 189 (28%) died.
Isolates from patients and production plant
Of the 439 clinical isolates from case-patients sequenced to date, 92% belong to sequence type 6 (ST6) and are highly genetically related.
The World Health Organization (WHO) said the percentage of cases infected with different strains may indicate more than one outbreak is ongoing.
A total of 86% of an unknown number of patients interviewed reported eating polony in the month before illness so RTE processed meat products became the focus of investigations.
The L. monocytogenes ST6 outbreak strain was found in the post-cooking processing environment at Enterprise Foods’ Polokwane production facility and on polony products.
“The outbreak strain isolates from patients and from the Enterprise Foods’ Polokwane production facility…differ by only ≤7 single base pairs out of 3 million,” said NICD.
“This extremely high level of genetic relatedness (99.99% similarity) means there can be no doubt that these L. monocytogenes ST6 strains are all linked, and that there is certainty that products manufactured at Enterprise Polokwane are the source of the outbreak.”
NICD said seven samples of RTE processed meat products made at the Enterprise Polokwane facility and sold at the Germiston factory tested positive for L. monocytogenes ST6.
Tests on environmental samples from RCL Foods’ Wolwehoek facility found L. monocytogenes but whole genome sequencing showed it was not the outbreak strain.
Imported mechanically deboned meat (MDM) has also not tested positive for the outbreak strain.