SA’s listeriosis outbreak: huge jump in deaths

The latest update (Feb 14) from the NICD (Nat Inst for Communicable Diseases) confirms that all nine provinces are affected; that cases have jumped from 852 on February 6 to 872 (20 more), BUT that there has been a huge jump from 107 deaths to 164! This update from expert food safety consultant, Lucia Anelich.

Somewhere in this beloved country of ours there is a source of hiding… It’s contaminating products and taking lives. Surely this could have been prevented by different behaviours? Prof Ryk Lues, on Twitter

In summary to date:

The strain that is still most frequently isolated belongs to sequence type ST6. This continues to indicate that these isolates originate from a single source, most likely a food product on the market or a series of food products produced in the same manufacturing environment.

The source may even be products that are consistently contaminated from batch to batch by persistent L. monocytogenes in the environment of the facility, particularly if there is no environmental control programme with associated effective cleaning and disinfection in place.

See more statistics in this NICD report: NICD Listeria Sitrep 14 Feb 2018

Outcome data is available for 597 of the 872 cases. Of these 597 cases, 164 deaths have been reported which drops the mortality rate slightly from 34% on 25 January and 30% on 06 February to 27.5% on 15 February 2018.

This rate is currently (this will likely change as the disease progresses and more cases are traced) 2-7% higher than general mortality rates reported in other countries i.e. 20-25%. Neonates ≤ 28 days continue to be the most affected group.

The source of the outbreak remains unknown. By all accounts, the outbreak has not yet peaked and more cases and deaths can be expected if the source is not found soon.

The rest of the world seems to be treating this outbreak as more of a crisis than we are in South Africa! Wendy Knowler, on Twitter

The World Health Organization (WHO) had a team in South Africa a few weeks back to assist the National Authorities and the NICD with this outbreak. A few key facilities were visited and there is apparently a “strong lead”.

As she has stated in previous communiques, that this is the worst documented listeriosis outbreak in global history. It remains so. Her international colleagues in European countries, Canada, Australia and the USA concur.

This communique, further information and interviews conducted can be found on the Anelich Consulting website at and by clicking on links provided.

See for regularly updated answers to Frequently Asked Questions.

Contact Dr Lucia Anelich at [email protected] for further assistance and scientific advice based on international best practice.


Listeria monocytogenes is the primary cause of the illness called listeriosis. The organism is an environmental pathogen and is found in soil, water, sewage, and decaying vegetation.

It can be readily isolated from humans, domestic animals, raw agricultural commodities, and food packing and processing environments (particularly cool damp areas that can contaminate food). It can cause two types of illnesses:

  • A mild, non-invasive illness (called listerial gastroenteritis), which shows typical symptoms of gastroenteritis i.e. fever and diarrhoea. This form of the illness is rarely diagnosed and usually passes quickly without severe effects.
  • A severe, invasive illness (called listeriosis). Listeriosis is characterised by a relatively high mortality rate i.e. ~20-25% compared to illnesses caused by most other foodborne pathogens (<1 % for Salmonella or E. coli O157). In the invasive form of the illness, the organism has moved beyond the gut and has infected other parts of the body.

Persons who have the greatest risk of experiencing listeriosis due to consumption of foods contaminated with L. monocytogenes are pregnant women and their foetuses, the elderly (over 65 years of age) and persons with weakened immune systems, for example, undernourished persons, people who have had organ transplants, those with HIV/AIDS, diabetes, cancer and other autoimmune diseases. 

Pregnant women: Pregnant women are approximately 20 times more likely than other healthy adults to get listeriosis. Pregnant women typically experience only fever and other flu-like symptoms, such as fatigue and muscle aches. However, infections during pregnancy can lead to miscarriage, stillbirth, premature delivery, or life-threatening infection of the newborn, such as meningitis.

People other than pregnant women: Symptoms can include headache, stiff neck, confusion, loss of balance, and convulsions in addition to fever and muscle aches.

People with invasive listeriosis usually report symptoms starting 1 to 4 weeks after eating food contaminated with L. monocytogenes; some people have reported symptoms starting as late as 70 days after exposure or as early as the same day of exposure (although this is very rare).

Foods that have caused outbreaks are typically contaminated from the environment during manufacturing/processing or packing.

Listeriosis is mainly associated with consumption of contaminated Ready-To-Eat (RTE) foods. Foods most often implicated in foodborne outbreaks globally, are:

  • Ready-to-eat deli meats (polonies, ham products etc) and hot dogs
  • Refrigerated pâtés or meat spreads 
  • Unpasteurized (raw) milk and dairy products
  • Soft cheese made with unpasteurized milk, such as queso fresco, Feta, Brie, Camembert 
  • Refrigerated smoked seafood 
  • Raw sprouts 
  • Pre-packaged salads 
  • Ice cream (not as common)

It is killed by thorough cooking and by temperatures used for pasteurisation of milk.

Source: Information supplied by Lucia Anelich, with thanks to her!