A total of 767 laboratory-confirmed listeriosis cases and 81 deaths have been reported to the National Institute of Communicable Diseases (NICD) since January 2017.
This number is likely to grow again with final outcome data only known for 30% (235) cases.
The World Health Organization (WHO) said South Africa was dealing with the largest ever Listeria outbreak when there were 748 lab-confirmed cases and 67 deaths.
The National Department of Health in South Africa held a press conference when there were 557 cases and 36 deaths at the start of December.
More than 40% of cases aged less than a month
Most cases are from Gauteng Province (60%, 462/767) followed by Western Cape (101) and KwaZulu-Natal (55) provinces. Females account for 55% (405/731) of cases.
Ages range from birth to 93 years and 41% (303/735) are aged ≤28 days.
The country has made listeriosis a notifiable disease meaning every diagnosed patient must be reported.
Genetic testing on samples of Listeria from patients suggests a single strain of the bacteria, sequence type 6 (ST6), is responsible for the majority of infections.
However, this strain has not yet been found in samples from processing facilities, abattoirs and food from patients’ homes so the source of the outbreak is not known.
Dr Aaron Motsoaledi, Minister of Health, said whole genome sequencing (WGS) analysis is being done.
“This ST6 strain has been identified in isolates from all nine provinces, and this finding supports the current working hypothesis, of a single source of food contamination causing the outbreak, i.e a single widely consumed food product or multiple food products produced at a single facility.”
Municipality slams link to tap water
The Nelson Mandela Bay municipality hit out at ‘unfounded allegations’ that its tap water is one of the outbreak causes.
“The municipality can confirm that the water coming out of its taps is safe to drink,” it said.
“The institution would like to condemn individuals who have been spreading inaccurate and irresponsible information about this serious issue through social media.
“This misinformation has not only caused panic across the city, it has also led to undue pressure on our Service Delivery Call Centre, which we use to deal with water leaks among others.”
Mpho Phalatse, member of the health and social development committee in Johannesburg, – which has reported 212 cases and 19 deaths – said it was important to educate the public.
“If we work together and be vigilant in our own spaces, we can stop the spread of Listeriosis and avoid unnecessary deaths. We are facing huge challenges as wrong information is spreading about Listeriosis.”
Christian Lindmeier, spokesperson for WHO, said the incubation period can range from six hours to 70 days which makes it difficult to establish the source and tough to prevent.
“You wouldn’t know what you ate three weeks ago – maybe the one particular food that made you sick three or four weeks later – this is the big challenge we face in this situation,” he said.