Listeriosis Outbreak in South Africa: A Comparative Analysis with Previously Reported Cases Worldwide

Abstract

Listeria species are Gram-positive, rod-shaped, facultative anaerobic bacteria, which do not produce endospores. The genus, Listeria, currently comprises 17 characterised species of which only two (L. monocytogenes and L. ivanovii) are known to be pathogenic to humans. Food products and related processing environments are commonly contaminated with pathogenic species. Outbreaks and sporadic cases of human infections resulted in considerable economic loss. South Africa witnessed the world’s largest listeriosis outbreak, characterised by a progressive increase in cases of the disease from January 2017 to July 2018. Of the 1060 laboratory-confirmed cases of listeriosis reported by the National Institute of Communicable Diseases (NICD), 216 deaths were recorded. Epidemiological investigations indicated that ready-to-eat processed meat products from a food production facility contaminated with L. monocytogenes was responsible for the outbreak. Multilocus sequence typing (MLST) revealed that a large proportion (91%) of the isolates from patients were sequence type 6 (ST6). Recent studies revealed a recurrent occurrence of small outbreaks of listeriosis with more severe side-effects in humans. This review provides a comparative analysis of a recently reported and most severe outbreak of listeriosis in South Africa, with those previously encountered in other countries worldwide. The review focuses on the transmission of the pathogen, clinical symptoms of the disease and its pathogenicity. The review also focuses on the major outbreaks of listeriosis reported in different parts of the world, sources of contamination, morbidity, and mortality rates as well as cost implications. Based on data generated during the outbreak of the disease in South Africa, listeriosis was added to the South African list of mandatory notifiable medical conditions. Surveillance systems were strengthened in the South African food chain in order to assist in preventing and facilitating early detection of both sporadic cases and outbreaks of infections caused by these pathogens in humans.

Discrimination of bacteria using whole organism fingerprinting: the utility of modern physicochemical techniques for bacterial typing

“…Listeria species are implicated as causative pathogens of Listeriosis, a foodborne microbial infection which recently gained notoriety in South Africa, where a significant number of victims died following ingestion of food predominantly contaminated with Listeria monocytogenes. 62,63 There is no doubt that rapid identification and classification of Listeria species is very desirable to guide effective therapeutic strategies, and thus to reduce mortality rates. Similarly, the discrimination of Bacillus genus was first attempted by Lin et al 64 and Beattie et al 65 Lin and colleagues analysed Bacillus cereus isolates using IR, which involved the identification and differentiation of ten B. cereus group isolates, including: B. cereus, B. mycoides, and B. thuringiensis strains, five Bacillus spp.…”

‘Preventing the next pandemic’ – A 2020 UNEP Frontiers Series Report on zoonotic diseases with reflections for South Africa

“…Between January 2017 and July 2018, South Africa experienced the largest listeriosis outbreak in the world to date. 8,9 The National Institute for Communicable Diseases (NICD) detected a total of more than 1000 laboratory-confirmed cases and 200 fatalities, 10,11 all of which were linked to eating contaminated polony (a type of bologna sausage). Polony was confirmed to contain Listeria monocytogenes after undergoing genome sequencing.…”

Effectiveness of Phage-Based Inhibition of Listeria monocytogenes in Food Products and Food Processing Environments

“…Listeria monocytogenes is rod-shaped Gram-positive, catalase positive, oxidase negative and facultative anaerobic bacteria [ 1 , 2 ]. It is naturally present in the environment and is found in locations such as soil, water, sewage, silage, plants and animals [ 2 , 3 ].…”

“…Listeria monocytogenes is rod-shaped Gram-positive, catalase positive, oxidase negative and facultative anaerobic bacteria [ 1 , 2 ]. It is naturally present in the environment and is found in locations such as soil, water, sewage, silage, plants and animals [ 2 , 3 ]. This organism grows at temperatures ranging from 1 to 45 °C [ 2 , 3 ] it also tolerates salt concentrations up to 10% and pH of 3.6–9.5 [ 2 ].…”