A Prolonged Outbreak of Enteric Fever Associated With Illegal Miners in the City of Matlosana, South Africa, November 2020-September 2022.

Background: In South Africa, the annual incidence of enteric fever averaged 0.1 per 100 000 persons between 2003 and 2018. During 2021 an increase in the number of enteric fever cases was observed. An outbreak investigation was conducted to determine the magnitude and source of the outbreak. Methods: We performed a cross-sectional descriptive study. Data were collected through telephonic or face-to-face interviews with cases or proxies via a standardized case investigation form. Whole genome sequencing was performed on all Salmonella Typhi isolates. Drinking water samples were collected, tested, and analyzed. Descriptive analysis was performed with Microsoft Excel. Results: Between January 2020 and September 2022, a cluster of 53 genetically highly related Salmonella Typhi isolates was identified from 5 provinces in South Africa. Isolates associated with the cluster showed ≤5 allelic differences, as determined following core genome multilocus sequence typing analysis. Most cases (60%, 32/53) were in the North West province. Males represented 68% (36/53). Of these, 72% (26/36) were aged 15 to 49 years, with a median age of 31 years. Where occupation was known within this age group, 78% (14/18) were illegal gold miners. Illegal miners reported illness onset while working underground. Five municipal tap water samples were tested and showed no evidence of fecal contamination. Conclusions: This outbreak predominantly affected illegal gold miners, likely due to the consumption of contaminated groundwater while working in a gold mine shaft. In addition, this investigation highlights the value of whole genome sequencing to detect clusters and support epidemiologic investigation of enteric fever outbreaks.

Imported Cholera Cases, South Africa, 2023.

Since February 2022, Malawi has experienced a cholera outbreak of >54,000 cases. We investigated 6 cases in South Africa and found that isolates linked to the outbreak were Vibrio cholerae O1 serotype Ogawa from seventh pandemic El Tor sublineage AFR15, indicating a new introduction of cholera into Africa from south Asia.

Enteric fever cluster identification in South Africa using genomic surveillance of Salmonella enterica serovar Typhi.

The National Institute for Communicable Diseases in South Africa participates in national laboratory-based surveillance for human isolates of Salmonella species. Laboratory analysis includes whole-genome sequencing (WGS) of isolates. We report on WGS-based surveillance of Salmonella enterica serovar Typhi (Salmonella Typhi) in South Africa from 2020 through 2021. We describe how WGS analysis identified clusters of enteric fever in the Western Cape Province of South Africa and describe the epidemiological investigations associated with these clusters. A total of 206 Salmonella Typhi isolates were received for analysis. Genomic DNA was isolated from bacteria and WGS was performed using Illumina NextSeq technology. WGS data were investigated using multiple bioinformatics tools, including those available at the Centre for Genomic Epidemiology, EnteroBase and Pathogenwatch. Core-genome multilocus sequence typing was used to investigate the phylogeny of isolates and identify clusters. Three major clusters of enteric fever were identified in the Western Cape Province; cluster one (n=11 isolates), cluster two (n=13 isolates), and cluster three (n=14 isolates). To date, no likely source has been identified for any of the clusters. All isolates associated with the clusters, showed the same genotype (4.3.1.1.EA1) and resistome (antimicrobial resistance genes: bla TEM-1B, catA1, sul1, sul2, dfrA7). The implementation of genomic surveillance of Salmonella Typhi in South Africa has enabled rapid detection of clusters indicative of possible outbreaks. Cluster identification allows for targeted epidemiological investigations and a timely, coordinated public health response.

Presentation and outcomes of Listeria-affected pregnancies in Johannesburg tertiary hospitals: A 2-year review.

OBJECTIVE: To describe maternal risk factors, presentations, peripartum findings, and pregnancy outcomes in Listeria monocytogenes-infected women. METHODS: A retrospective descriptive case review. The records of 51 pregnant women infected with listeriosis who delivered infants between February 1, 2016 and February 28, 2018 at three academic hospitals in Johannesburg, South Africa, were included. The diagnosis of listeriosis was made on maternal/neonatal-sampled blood or tissue cultures. RESULTS: Forty-eight (82.3%) Listeria infections of maternal and neonatal listeriosis were diagnosed on blood culture. The median gestational age at diagnosis was at a preterm gestation of 33 (20-43) weeks. Twenty-eight women (54.9%) had normal vaginal deliveries. Precipitous labor was described in 18 (39%) of these women. Fetal distress was the indication for cesarean section in 22 (41.2%) women. Meconium-stained amniotic fluid was found in 21 (61.7%) women at the time of delivery. The category of very low birth weight had 14 (27.4%) neonates with an Apgar score of less than 7 at 5 min. Maternal morbidities included chorioamnionitis (3 [5.8%]) and puerperal infections (7 [13.7%]). The HIV-positive anemic women had a tendency towards listerial infections. CONCLUSIONS: Symptoms of listeriosis were non-specific and diagnosis was detected on blood culture sampling. Risk factors included HIV seropositivity and were associated with puerperal infections and anemia.

Emergence of Vibrio cholerae O1 Sequence Type 75, South Africa, 2018-2020.

We describe the molecular epidemiology of cholera in South Africa during 2018-2020. Vibrio cholerae O1 sequence type (ST) 75 recently emerged and became more prevalent than the V. cholerae O1 biotype El Tor pandemic clone. ST75 isolates were found across large spatial and temporal distances, suggesting local ST75 spread.

Leveraging gains from African Center for Integrated Laboratory Training to combat HIV epidemic in sub-Saharan Africa.

BACKGROUND: In sub-Saharan Africa, there is dearth of trained laboratorians and strengthened laboratory systems to provide adequate and quality laboratory services for enhanced HIV control. In response to this challenge, in 2007, the African Centre for Integrated Laboratory Training (ACILT) was established in South Africa with a mission to train staffs from countries with high burdens of diseases in skills needed to strengthen sustainable laboratory systems. This study was undertaken to assess the transference of newly gained knowledge and skills to other laboratory staff, and to identify enabling and obstructive factors to their implementation. METHODS: We used Kirkpatrick model to determine training effectiveness by assessing the transference of newly gained knowledge and skills to participant's work environment, along with measuring enabling and obstructive factors. In addition to regular course evaluations at ACILT (pre and post training), in 2015 we sent e-questionnaires to 867 participants in 43 countries for course participation between 2008 and 2014. Diagnostics courses included Viral Load, and systems strengthening included strategic planning and Biosafety and Biosecurity. SAS v9.44 and Excel were used to analyze retrospective de-identified data collected at six months pre and post-training. RESULTS: Of the 867 participants, 203 (23.4%) responded and reported average improvements in accuracy and timeliness in Viral Load programs and to systems strengthening. For Viral Load testing, frequency of corrective action for unsatisfactory proficiency scores improved from 57 to 91%, testing error rates reduced from 12.9% to 4.9%; 88% responders contributed to the first national strategic plan development and 91% developed strategies to mitigate biosafety risks in their institutions. Key enabling factors were team and management support, and key obstructive factors included insufficient resources and staff's resistance to change. CONCLUSIONS: Training at ACILT had a documented positive impact on strengthening the laboratory capacity and laboratory workforce and substantial cost savings. ACILT's investment produced a multiplier effect whereby national laboratory systems, personnel and leadership reaped training benefits. This laboratory training centre with a global clientele contributed to improve existing laboratory services, systems and networks for the HIV epidemic and is now being leveraged for COVID-19 testing that has infected 41,332,899 people globally.

Whole-genome sequencing to investigate two concurrent outbreaks of Salmonella Enteritidis in South Africa, 2018.

Salmonella enterica serotype Enteritidis (Salmonella Enteritidis) is a major cause of foodborne disease outbreaks worldwide. In 2018, two concurrent outbreaks of Salmonella Enteritidis gastroenteritis in one district of South Africa were investigated. We describe the use of whole-genome sequencing (WGS) analysis of bacterial isolates to assist with the investigation of these outbreaks. Outbreak A affected children (n=27) attending a day-care centre, while outbreak B affected adults (n=16) who ate breakfast at the same restaurant. Salmonella Enteritidis was isolated from stool samples in both outbreaks (four children in outbreak A; 12 restaurant customers and three restaurant food-handlers in outbreak B). In outbreak B, Salmonella Enteritidis was isolated from three food retention samples (raw chicken egg, hollandaise sauce and rocket-herb). Available isolates from both outbreaks (n=13) were investigated using WGS analysis. Sequencing data for isolates were analysed at the EnteroBase web-based platform and included core-genome multi-locus sequence typing (cgMLST). Isolates with epidemiological links to the restaurant (n=10) and day-care centre (n=3), were shown by cgMLST to be highly genetically related, with no more than five allele differences when comparing one isolate against another. On food history, eggs and hollandaise sauce were the common food items consumed by ill restaurant customers. Unfortunately, Salmonella Enteritidis isolated from the egg and hollandaise sauce were not available for WGS analysis. Our investigation concluded that the two concurrent outbreaks were caused by a highly related strain of Salmonella Enteritidis, suggesting the possibility of a common contaminated food source, of which contaminated eggs are strongly implicated.

Outbreak of Listeriosis in South Africa Associated with Processed Meat.

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.