By: Pooja Sharma

The world’s worst Listeriosis outbreak in South Africa has attracted major attention after the death toll rose to 61 from 36 in past month. The worst part being 40% of the fatality cases alone account for neonates – an infant less than 4 weeks old. As SA grapples with the outbreak that experts have named as the worst outbreak ever, worldwide, the origins of the outbreak still remains a mystery. The researchers have confirmed that the outbreak is caused by a single source.

Case Count:

Ministry of Health has declared that there are around 748 laboratory confirmed cases of Listeria that have occurred in South Africa since the start of 2017. The possible number of cases could grow in the near time. The Department of Health (DoH) declared Listeriosis as a notifiable disease on December 15. This indicates a very serious situation. South Africa has a massive problem on its hands dealing with one of the largest single outbreaks of Listeria recorded. Additional 31 cases of Listeriosis have been confirmed since January 3, 2018. Here are the cities that are most affected.

  • Gauteng -61%
  • Western Cape -13%
  • KwaZulu-Natal -7%

65% of the total cases occurred in the public hospitals and around 35% occurred in the private hospitals.

Source Mapping:

The Department of Health (DoH) has pointed out that the evidence in this outbreak is one source of food that is acting as a vector of transmission of the pathogen. 91% of the cases have presented one strain of bacteria as the cause of Listeriosis infection. The strain of bacteria involved in these cases is ST6.  Since so many cases are linked to one strain of bacteria, it is highly likely that there is one source of outbreak for all the infections.

The problem finding the source is more challenging when only 18.43% of all those infected have been traced so far. The sooner National Institute of Communicable Diseases (NICD) and Department of Health (DoH) are able to trace all those infected, the better. Once they are able to find the patients, patient interviews can help in identifying the common point of all the cases and reduce the number of potential premises of infection.

Nonetheless, a Sovereign Foods abattoir has been closed after bacteria that causes Listeria was found there. Sovereign Foods is based in Eastern Cape and is one of the major poultry producers in Africa. But, the ST6 strain that is responsible for the deadly outbreak was not present in the abattoir, confirmed Health Minister Aaron Motsoaledi. A chicken sample collected from a patient’s home tested positive for Listeria Monocytogenes. The chicken when traced back to store was traced to abattoir. All other samples collected from abattoir tested negative for the strain though.

Outbreaks of all foodborne illnesses follow a pattern – growing in numbers, peaking in patterns and then, declining in numbers over time – says Dr. Lucia Anelich, food microbiologist and director of Anelich Consulting who offers food safety expertise. She also based her analogy on the fact that the contaminated products are being sold and consumed over time until all the product has been consumed and its whole batch is not available in the market. But, that is only the case if the processing facility does not have listeria in the environment of the facility. If that is what’s happening, then there is continuous contamination of freshly produced product over time.


There is a lot of concern regarding the underestimation of cases in the outbreak. Underestimation of the total case count also means understated fatality rates. National Institute of Communicable Diseases (NICD) have final data for only around 21% of those infected, i.e. 134 patients so far, of which 45.5% have already passed away. If a death toll of 45.5% is considered to a total case count of 748 patients that are accounted so far, then around 300 patients should be dead.

Next concern, as mentioned above, is about a processing facility being contaminated with the Listeria monocytogenes. This can lead to a high number of cases that are continuous and peak with time. Therefore, it is important to link as soon as possible the strain of Listeriosis to a processing facility. This would ensure adequate control measures to be taken to stop the outbreak and also prevent any future ones from arising in that facility.

Another concern is poor record keeping in Gauteng hospitals that is also to be blamed for hindering source of Listeriosis. Authorities have urged the hospital to keep a complete check of patient’s details to find out the source as soon as possible. A possible lag in reporting due to public holidays has also led to decreased data about the illnesses.

The last major concern in the worst outbreak ever is the group of people affected in the outbreak. The outbreak has severely affected neonates. And of those affected, 96% had early onset of disease, i.e. from birth to six days after they were born. It is quite clear that these neonates are affected by their pregnant mothers. Pregnant women who are affected by Listeria can develop complications such as miscarriage, premature birth, etc. Even if the baby is born, it can become severely ill soon after birth.

What is Listeriosis?

It lurks in some of the most popular food and hides under your fridge – Listeriosis is serious infection that is caused by food contaminated with Listeria monocytogenes. In US, an estimated 1600 people become ill each year by Listeriosis and around 260 of them die. The fatality rate of Listeriosis is around 20% – which is highest among the most common food illnesses like Salmonella and E. coli that occur. It can be higher for susceptible groups of people such as pregnant women, children, older people and those with weakened immune system.

Unless further information on the source of outbreak, it is crucial that you practice good hygiene and follow proper food safety procedures especially if you are pregnant. Foods most often involved in outbreaks are deli meats, unpasteurized milk or dairy, hot dogs, meat spreads, raw sprouts, refrigerated smoked seafood and pre-packaged salads. Other foods can get contaminated by cross-contamination during manufacturing, processing or packing.


Food Poisoning Lawyer–but-still-no-sign-of-culprit/