Fourteen deaths in four days. That's what the National Institute of Communicable Diseases’ latest listeriosis outbreak report reveals.

A total of 81 people have died in South Africa from the disease‚ contracted from eating food contaminated with the food borne pathogen Listeria‚ according to the NICD. In early December‚ the number of dead totalled 36.

The number of confirmed cases - in what has been described as the biggest listeriosis outbreak - is now 767‚ up from 748 on January 12. In South Africa‚ te outbreak is spread across all nine provinces. Scarily‚ the 235 cases for which the NICD has “outcome data” reveals the death rate to be an alarming 34%.

“This rate will likely change as the disease progresses and more cases are traced‚” said Pretoria-based food safety expert Dr Lucia Anelich. “The general mortality rates reported in other countries range between 20 and 25%.”

As the number of confirmed cases‚ and deaths‚ continue to rise‚ the source - revealed by genome sequencing to be a particular strain‚ suggesting a single food or range of foods - remains unknown.

About 40% of those who have died were newborn babies‚ 96% of them less than a week old.

Pregnant women are 20 times more likely to get listeriosis than other healthy adults.

Anelich says the “culprit” is most likely a product consumed "extremely often" across the country.

Listeriosis symptoms - which are 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 these are deli meats like 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 said.