Thomas, J.Govender, N.McCarthy, K.M.Erasmus, L.K.Doyle, T.J.Allam, M.Ismail, A.Ramalwa, NtsieniSekwadi, P.Ntshoe, Genevie M.Shonhiwa, A.Essel, V.Tau, N.Smouse, S.Ngomane, H.M.Disenyeng, B.Page, Nicola AnneGovender, N.P.Duse, A.G.Stewart, R.Thomas, T.Mahoney, D.Tourdjman, M.Disson, O.Thouvenot, P.Maury, M.M.Leclercq, A.Lecuit, M.Smith, Anthony MariusBlumberg, Lucille Hellen2021-10-272021-10-272020-02TThomas, J., Govender, N., McCarthy, K.M. et al. Outbreak of listeriosis in South Africa associated with processed meat. New England Journal of Medicine 2020 Feb 13; 382:632. https://doi.org/10.1056/NEJMoa19074620028-4793 (print)1533-4406 (online)10.1056/NEJMoa1907462http://hdl.handle.net/2263/82262BACKGROUND: 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.en© 2020 Massachusetts Medical SocietyFood-borneOutbreakListeriosisSouth Africa (SA)Article