Update on Listeriosis Outbreak in South Africa

National Department of Health

05 January 2017

By Dr Lucia Anelich

The NICD has provided the latest update on the listeriosis outbreak in South Africa – attached to this note as at 03 January 2018. In summary:
 There are now 717 confirmed cases (550 on 5 December) i.e. 167 more in a period of 30 days.
 61 deaths have been reported.
 Neonates remain the most affected.
 NICD has been tracking this listeriosis outbreak since 03 January 2017 – an entire year!
 A major percentage (91%) of clinical isolates belong to the same sequence type i.e. ST6 – this means that these isolates originate from a single source, most likely a food product on the market or a series of food products produced in the same manufacturing environment.
 The outbreak is across all nine provinces.

Investigation of an abattoir in Tshwane:
Environmental Health Practitioners from the City of Tshwane recently investigated a Tshwane patient hospitalised with listeriosis. A chicken sample collected from the fridge at the patient’s home tested positive for Listeria monocytogenes. This chicken was traced back to the store, and from there traced back to the abattoir it was sourced from. The Environmental Health Practitioners visited the abattoir and collected food and environmental samples, several of which tested positive for L. monocytogenes. As a precaution, the abattoir was closed pending further investigations. The abattoir-related L. monocytogenes strains are undergoing testing (whole genome sequencing i.e. latest technology) to assess whether they are related to the ST6 outbreak strain or not; these results will only be available next week.

Even though Listeria monocytogenes has been found in a specific abattoir, precise confirmation of the strain is still required. Much work then needs to be done to match the outbreak strain with a single / multiple food products originating from the same manufacturing environment, including clear evidence that the apparently contaminated food was ingested by the majority of people constituting 91% of the cases, across nine provinces.

The significance of isolating L. monocytogenes from raw poultry, which is to be cooked before consumption (when the bacterium is killed), is questionable, considering that the bacterium is normally present in the environment in which animals are bred and raised. Avoiding cross contamination from raw to cooked foods is of immense value in preventing foodborne disease in general in the home, in restaurant environments and in the manufacturing sector and is thus, just as applicable to listeriosis. Therefore, consumer education and awareness as well as correct management of food safety hazards are key factors in preventing foodborne disease. As things stand, the source of this outbreak is still not known.

Dr Anelich concurs with her international colleagues from business, academia and governments (in Europe, Australia, Canada and the USA) that this is the worst documented listeriosis outbreak in global history.

Further information can be found on the Anelich Consulting website at www.anelichconsulting.co.za and by clicking on various links. Contact Dr Lucia Anelich at la@anelichconsulting.co.za for further assistance and scientific advice based on international best practice.