Outbreak of Listeriosis in South Africa Associated with Processed Meat

Juno Thomas (1) , Nevashan Govender , Kerrigan Mccarthy , Linda Erasmus , Timothy Doyle , Mushal Allam , Arshad Ismail , Ntsieni Ramalwa , Phuti Sekwadi , Genevie Ntshoe , Andronica Shonhiwa , Vivien Essel , Nomsa Tau , Shannon Smouse , Hlengiwe Ngomane , Bolele Disenyeng , Nicola Page , Nelesh Govender (2) , Adriano Duse , Rob Stewart , Teena Thomas , Deon Mahoney , Mathieu Tourdjman (3) , Olivier Disson (4, 5, 6) , Pierre Thouvenot (5, 6, 4) , Mylène M Maury (5, 6, 4) , Alexandre Leclercq (5, 6, 4) , Marc Lecuit (4, 7, 8, 6, 9, 10, 5) , Anthony Smith (2) , Lucille Blumberg (1)

1 NICD - National Institute for Communicable Diseases [Johannesburg]
2 WITS - University of the Witwatersrand [Johannesburg]
3 Santé publique France - French National Public Health Agency [Saint-Maurice, France]
4 Biologie des Infections - Biology of Infection
5 CNRL - Centre National de Référence Listeria - National Reference Center Listeria
6 CC-OMS / WHO-CC - Centre collaborateur de l'OMS Listeria / WHO Collaborating Centre Listeria
7 Hôpital Necker - Enfants Malades [AP-HP]
8 Imagine - U1163 - Imagine - Institut des maladies génétiques (IHU)
9 UPCité - Université Paris Cité
10 Service des Maladies infectieuses et tropicales [CHU Necker]

Background An outbreak of listeriosis was identified in South Africa in 2017. The source was unknown. Methods We conducted epidemiologic, trace-back, and environmental investigations and used whole-genome sequencing to type Listeria monocytogenes isolates. A case was defined as laboratory-confirmed L. monocytogenes infection during the period from June 11, 2017, to April 7, 2018. Results A total of 937 cases were identified, of which 465 (50%) were associated with pregnancy; 406 of the pregnancy-associated cases (87%) occurred in neonates. Of the 937 cases, 229 (24%) occurred in patients 15 to 49 years of age (excluding those who were pregnant). Among the patients in whom human immunodeficiency virus (HIV) status was known, 38% of those with pregnancy-associated cases (77 of 204) and 46% of the remaining patients (97 of 211) were infected with HIV. Among 728 patients with a known outcome, 193 (27%) died. Clinical isolates from 609 patients were sequenced, and 567 (93%) were identified as sequence type 6 (ST6). In a case–control analysis, patients with ST6 infections were more likely to have eaten polony (a ready-to-eat processed meat) than those with non-ST6 infections (odds ratio, 8.55; 95% confidence interval, 1.66 to 43.35). Polony and environmental samples also yielded ST6 isolates, which, together with the isolates from the patients, belonged to the same core-genome multilocus sequence typing cluster with no more than 4 allelic differences; these findings showed that polony produced at a single facility was the outbreak source. A recall of ready-to-eat processed meat products from this facility was associated with a rapid decline in the incidence of L. monocytogenes ST6 infections. Conclusions This investigation showed that in a middle-income country with a high prevalence of HIV infection, L. monocytogenes caused disproportionate illness among pregnant girls and women and HIV-infected persons. Whole-genome sequencing facilitated the detection of the outbreak and guided the trace-back investigations that led to the identification of the source.

Domaines: Sciences du Vivant [q-bio]; Médecine humaine et pathologie; Santé publique et épidémiologie

Juno Thomas, Nevashan Govender, Kerrigan Mccarthy, Linda Erasmus, Timothy Doyle, et al.. Outbreak of Listeriosis in South Africa Associated with Processed Meat. New England Journal of Medicine, 2020, 382 (7), pp.632-643. ⟨10.1056/NEJMoa1907462⟩. ⟨pasteur-02586017⟩