According to the National Institute for Communicable Diseases, at present, the source of the outbreak is not known.  Although, according to press reports cooked chicken and other deli meats such as ham and ‘polony’ are high on the list of suspects for causing the world’s worst ever recorded listeriosis outbreak.

As of 23 January 2018, a total of 820 laboratory-confirmed listeriosis cases have been reported to NICD since 01 January 2017 (Figure 1). Most cases have been reported from Gauteng Province (59%, 486/820) followed by Western Cape (13%, 105/820) and KwaZulu- Natal (7%, 59/820) provinces. Cases have been diagnosed in both public (66%, 542/820) and private (34%, 278/820) healthcare sectors. Diagnosis was based most commonly on the isolation of Listeria monocytogenes in blood culture (71%, 579/820), followed by CSF (23%, 188/820).

Where age was reported (n=784), ages range from birth to 93 years (median 18 years) and 42% (329/784) are neonates aged ≤28 days (Figure 2). Of neonatal cases, 96% (317/329) had early-onset disease (birth to ≤6 days). Females account for 55% (431/783) of cases where gender is reported. Final outcome data is available for 29% (238/820) of cases, of which 34% (82/238) died.

Municipal Environmental Health Practitioners in all provinces have embarked on systematic inspection and sampling of meat & poultry production, processing, and packaging facilities. Cases of listeriosis will continue to be investigated, with trace back and further investigation of any positive food/environmental samples.