A total of 748 laboratory-confirmed listeriosis cases and 67 deaths have been reported to the National Institute of Communicable Diseases (NICD) since January 2017.
Most are from Gauteng which includes where Johannesburg and Pretoria, followed by Western Cape and KwaZulu-Natal provinces.
The second largest outbreak of listeriosis was in 2011, when the US had 147 cases and prior to that Italy had a large outbreak in 1997.
Incubation period is ‘big challenge’
It has an incubation period that can range from six hours to 70 days.
The United Nation’s health agency said this period makes it difficult to establish the source and tough to prevent.
South Africans should practice WHO’s ‘Five Keys to Safer Food’ that include washing hands before and often during food preparation; separating raw meat, poultry and seafood from other foods; and cooking foods thoroughly, especially meat, poultry, eggs and seafood.
Christian Lindmeier, spokesperson for WHO, said newborns are about 40% of the infected people.
“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.
“We have a total now of 748 laboratory-confirmed cases, but then again, this is difficult because many cases may not be even reported.”
Lindmeier added cases are in all socio-economic backgrounds since the outbreak was declared on 5 December.
Listeriosis a notifiable disease
South Africa has made listeriosis a notifiable disease whereby every such diagnosed patient must be reported.
Lindmeier added: “[That’s] important because Listeriosis is such a big challenge because it is not just the health sector that is involved, it involves all sectors – the food industry, farming – and to find the source is really difficult simply because the incubation period is so long.”
Dr Rufaro Chatora, country representative from the WHO, said it and the international community are ready to support the country in fighting the outbreak.
“The country has also implemented some important measures such as making Listeriosis a notifiable condition for the first time ever. This is helping to track the diseases.”
Genetic testing on samples of Listeria from diagnosed patients suggests a single strain of the bacteria, sequence type 6 (ST6), is responsible for the majority of infections.
This implies a single source of contamination is causing the outbreak such as a single widely consumed product or multiple food products made at a single facility.
The ST6 strain has so far not been found in samples from processing facilities, abattoirs and food from patients’ homes.
The Consumer Goods Council of South Africa (CGCSA) said its members continue to assist the Department of Health (DoH) to contain the outbreak.
“We also wish to confirm that retailer and manufacturer members already adhere to the strictest hygienic and food safety standards, which are regularly monitored by the DoH. Our concern is always the health of consumers and our members will not compromise on this non-negotiable requirement.
“CGCSA members have ongoing routine testing schedules in place to monitor all food products for pathogens and to take action if these organisms are detected.
“The members have, as a result of the latest outbreak, taken additional precautionary measures to ensure the safety of food products sold to consumers.”