The death count in South Africa’s listeriosis outbreak - the worst documented listeriosis outbreak in global history - has topped 100.

The National Institute of Communicable Diseases (NICD) announced on Tusesday that the number of confirmed listeriosis cases is now 852‚ and 107 people have died‚ the death rate - based on the outcome data for 355 cases - now sitting at 30%.

Of those confirmed cases‚ 42% were babies of less than a month old‚ pregnant women being 20 times more likely to get listeriosis than other healthy adults.

Contracted from eating food containing the pathogen listeria‚ listeriosis is the most deadly of food-borne diseases‚ the death rate in other documented outbreaks being up to one in four.

And still the source of the outbreak - thought to be a food product or range of products from one company - remains unknown.

Most cases - 59% - have been reported in Gauteng‚ with 13% of cases in the Western Cape and 7% in KZN; roughly two thirds of cases being confirmed in state hospitals and a third in private hospitals.

Pretoria-based food safety expert Dr Lucia Anelich says the “culprit” is most likely a product consumed by consumers across the country and “extremely often”.

Listeriosis symptoms - typically flu-like - develop any time between two and 30 days after eating food contaminated with the listeria pathogen.

High on the list of foods known to have caused other listeriosis outbreaks are ready-to-eat foods which consumers don’t cook or heat before eating‚ primarily deli meats - slices of ham‚ polony‚ cooked chicken and the like.

“Deli meats are obviously consumed by a wide variety of people in the population‚ whether it’s a cheaper cut or a more expensive one‚” Anelich says.

Municipal environmental health practitioners in all provinces are systematically inspecting and taking samples at food production‚ processing and packaging facilities.