Listeriosis Disease Outbreak News 20 March 2018 South Africa is experiencing an outbreak of listeriosis, a serious foodborne disease. This outbreak is ongoing since the beginning of 2017. Between 1 January 2017 and 14 March 2018, 978 laboratory-conﬁrmed listeriosis cases have been reported to National Institute for Communicable Diseases (NICD) from all provinces. Further details on the epidemiology of this event can be found at http://www.nicd.ac.za. To date, 748 cases were reported in 2017, and 230 cases in 2018. Around 80% of cases are coming from three provinces: 581 (59%) from Gauteng, 118 (12%) from Western Cape and 70 (7%) from KwaZulu-Natal provinces. The ﬁnal outcome at the end of hospitalization is known for 674 (69%) of the cases of which 183 (27%) have died. This is comparable to the case fatality rate of other recorded listeriosis outbreaks worldwide. Most of the cases are in people with a higher risk for a severe disease outcome. These includes neonates, pregnant women, the elderly and immuno-compromised persons. In this outbreak, 41.9% of the cases are newborns baby who got infected during pregnancy or delivery. Recent results from the whole genome sequencing analysis showed that a strain of Listeria monocytogenes with the same sequence (5T6) as the outbreak strain was identiﬁed in a widely consumed ready-to-eat processed meat product (Polony). The same strain was also found in the processing environment of the manufacturer of the implicated product. This product is believed to be the source of the outbreak, and this was announced by the Ministry of Health South Africa on 4 March 2018. The company and three of its retailers export to 15 countries in the African region: Angola; Botswana; DRC; Ghana; Lesotho; Madagascar; Malawi Mauritius; Mozambique; Namibia; Nigeria; Swaziland; Uganda; Zambia; and Zimbabwe. All have issued recalls for the implicated products. In addition, environmental samples from other food production companies have also tested positive for listeria (but with strains different from the outbreak strain). These companies have issued food recalls. Some of their products have also been exported to some of the countries listed above. Some of the investigated cases in South Africa are affected by a strain different from the main outbreak strain (based on whole genome sequencing) and this may indicate that more than one outbreak is ongoing. Comprehensive investigations to identify the source of these other outbreaks should be conducted. Epidemic curve of laboratory-conﬁrmed listeriosis cases by epidemiological week and date of sample collection and province, South Africa, 01 January 2017 to 12 March 2018 (n=978): Source: National Institute for Communicable Diseases (NICD), South Africa. Public Health Response:
- The Minister of Health held a press conference on 4 March 2018 to announce the source of the outbreak.
- Following the source identiﬁcation; the national authorities have taken measures to limit further infections and associated mortality, including but not limited to the issuance of safety recall notices, compliance notices, and measures related to exportation of implicated products and risk communication with vulnerable groups.
- The Southern African Development Community (SADC) Health ministers held a meeting in Johannesburg on 15 March to share information and to enhance preparedness and response for Listeriosis. Health Ministers were further reminded of their rights and obligations under the lHR with regards to additional health measures for international travel and trade.
- Listeriosis has been made a notiﬁable medical condition in South Africa Since December 2017.
- National risk communication activities have been initiated since December 2017 around the WHO ﬁve keys to safer food messages.