Briefing the media in Pretoria on Monday, Motsoaledi said the source of the outbreak, which has already claimed the lives of 61 people since January 2017, was proving to be extremely difficult to find.

Listeriosis is a bacterium disease found in soil, water and vegetation, which contaminates food sources, such as animal products and fresh produce.

"It’s like searching for a needle in a haystack and the problem is that we are still looking for the haystack before we start searching for the needle, we don’t even know yet which haystack it is, that’s how difficult this thing is," Motsoaledi said.

The National Institute of Communicable Diseases (NICD) has identified the specific strain of listeriosis using Genome Sequencing Analysis, which used isolates from the blood of infected patients, food samples and food production isolates.

Of the clinical isolates taken from patients’ blood, 91% are sequence type six, which represents a single strain of listeria, explained Motsoaledi.

Link to food source unknown

Despite the strain being identified, it has not yet been linked to any food or a specific food production site.

Since Motsoaledi’s announcement of the outbreak on December 5, 2017, a total of 170 extra laboratory-confirmed cases of listeriosis have been reported, bringing the total number of confirmed cases to 727.

The minister said, of the 170 confirmed cases, 119 occurred between December 5, 2017 and January 5, 2018.

Only five patients have been traced in the 119 new cases, of which three had died.

The death toll has also risen since December 5, 2017, from 36 confirmed deaths to 61, as more patients are traced.

Motsoaledi added that another difficulty in finding the source of the outbreak was tracking the patients.

Of the 727 confirmed cases, the department has so far only managed to trace 134 patients - 18% of the total cases.

"This means we still have a very long way to go in searching," said Motsoaledi.

He added that the difficulty in tracing actual patients was that many people did not have addresses or they were routinely treated and discharged as listeriosis was not a notifiable disease before December 15, 2017, when it was gazetted.

"You find patients with listeria, you treat them and they go home."

It has since been added to the list of notifiable diseases which makes it a requirement for health practitioners, clinics and hospitals to report cases to the government.

High awareness of listeria

"What we have now is very active reporting of patient cases because it's a notifiable disease, there is high awareness of listeria now and as soon as a positive culture is found it's reported," specialist microbiologist, Professor Lucille Blumberg, said.

Despite the difficulties, Motsoaledi said work was still being done to trace patients and plans to inspect food processing facilities as well as packaging plants to take samples was underway.

Motsoaledi has again urged anyone, who experiences symptoms of listeriosis, to seek medical attention immediately.

He said those who contract the disease will have flu-like symptoms including diarrhoea, fever, general body pains and weakness.

The disease can cause meningitis, which is an infection of the brain, and septicaemia which is an infection of the bloodstream, he said. Both can be fatal.

However, Motsoaledi stressed that, while the disease is serious and dangerous, it is treatable with antibiotics.

The minister also appealed to health workers to pay special attention to pregnant women and neonates - infants younger than one month, saying that statistics show that neonates are the worst affected and become infected by their mothers at birth.

News24