School of Public Health (ETDs)

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A survey of the professional quality of life of pharmacists and rehabilitation therapists at three public sector hospitals in Gauteng, South Africa
(2024) Moyo, Nonkazimulo
Background- The global goal of Universal Health Coverage (UHC) cannot be achieved without a wellmotivated and productive health workforce. Central to their motivation and productivity is the notion of professional quality of life (ProQOL) that captures both the positive and negative emotions of caring work. However, there is a dearth of empirical studies on the ProQOL of pharmacists and rehabilitation therapists, especially in an African setting. Study aim -The aim of the study was to examine the self-reported ProQOL of pharmacists and rehabilitation therapists at three public sector hospitals in the Gauteng Province of South Africa. Methodology- During 2021, a cross-sectional analytical study was conducted at three public sector hospitals in the Gauteng Province of South Africa. Following informed consent, all eligible pharmacists, pharmacist assistants, occupational therapists, physiotherapists and speech therapists and audiologists completed a self-administered questionnaire electronically. In addition to sociodemographic information, the questionnaire obtained information on compassion satisfaction, burnout, and secondary traumatic stress using the ProQOL scale (version 5) and work-related experiences during the COVID-19 pandemic. STATA® 17 was used for descriptive and multivariate analysis of the survey data. Results- A total of 118 pharmacists and rehabilitation therapists completed the survey. The majority were female (83.00%), single (63.46%), with mean age 30.77 years (SD=9.08). The results revealed moderate mean scores for compassion satisfaction (39.62; SD=5.48), burnout (24.26; SD=5.12) and secondary traumatic stress (23.03; SD=6.31). The predictors of compassion satisfaction were moderate positive COVID-19 experiences score (β=+2.61;95% CI 0.54; 4.68; p=0.014) and high positive COVID-19 experiences score (β =+ 2.68; 95%CI 0.40; 4.96; p=0.021); moderate overall job satisfaction score (β =+ 3.17; 95% CI 0.16; 6.18; p=0.039) and high overall job satisfaction score (β =+ 7.26; 95% CI 4.06; 10.47; p<0.001). The predictors of burnout were being single (β=+2.02 95% CI 0.07; 3.97; p=0.042), full professional registration (β=+4.23; 95% CI 1.79; 6.67; p=0.001), direct involvement in patient care (β=+3.24; 95% CI 0.22; 6.26; p=0.036) and reporting a heavy workload (β=+ 2.61; 95% CI 0.75; 4.48; p=0.007). The predictors of secondary traumatic stress were being male (β=+ 3.26; 95% CI 0.36; 6.15; p=0.028), and full registration (β=+ 5.72; 95% CI 2.41; 9.03; p<0.001). Conclusion- The ProQOL of pharmacists and rehabilitation therapists is influenced by a combination of individual, workplace, and health system factors, suggesting the need for a multifaceted approach to optimise their contribution to the achievement of UHC. Such approach should include provincial health, hospital management, and peer support as well as self-care activities.
A visual analytics approach to characterising disease progression among adults with chronic diseases in rural Agincourt northeast South Africa
(University of the Witwatersrand, Johannesburg, 2024) Nhlapho, Mapule Dorcus; Kabudula, Chodziwadziwa
Chronic diseases pose a significant challenge to the healthcare systems in South Africa, calling for innovative approaches for comprehensive understanding and management. This research study utilizes the Agincourt HDSS-Clinic dataset to design and implement a visual analytics system using the R Shiny web application framework. Focused on adults with chronic diseases, the tool employs dynamic visualizations to show patterns of healthcare utilization and disease progression. Through the R Shiny platform, the system provides a user-friendly interface for exploring and interpreting complex data, offering valuable insights into patient healthcare behaviours and the dynamics of chronic illnesses. The study used data from a total of 26 426 patients consisting of 19 265 (73%) females and 7 161 (27%) males. The study revealed previously unrecognized associations between specific chronic conditions including the existence of a substantial intersection between HIV, Hypertension, and Diabetes with 101 patients experiencing the coexistence of all the three conditions. Notably, the visual analytics system facilitated the identification of distinct healthcare utilization patterns across different demographic groups highlighting the most frequently visited health facility accounted for 5 912 patient visits overall while the least visited health facility accounted for 1 447 patient visits. The findings underscore the effectiveness of visual analytics in uncovering trends within complex datasets. The implications of these findings extend beyond the immediate research scope, influencing healthcare strategies and contributing to the ongoing discussions on innovative solutions for chronic disease management. This study contributes to the evolving field of visual analytics in healthcare, demonstrating the potential for such tools to inform decision-making and enhance patient outcomes
Activity and time spend patterns of residents in low-income settlements in the City of Johannesburg, South Africa
(2024) Bhuda, Hope Prudence Boipelo
Background: Human health risk assessment is concern about estimating the population exposure (HHRA) for environmental pollutants or contaminants. Exposure assessment for population-level require time-activity pattern distributions in association to microenvironments where individuals reside and spend their time. Time-activity patterns in South Africa have not been adequately explored, which may lead to wrong dose estimation for health risk assessment. No in-depth and systematic analyses of time-activity patterns in low-income communities have been done to date in South African context. Aim: The aim of this study was to describe variations on time-activity patterns based on age, sex and socioeconomic status amongst residents of low-income communities in South African township (Matholesville informal settlement). Methodology: A cross-sectional study design was adopted to assess time-activity patterns amongst lowincome residents in South African townships. One Hundred and Thirty (130) households were selected randomly to participate in the study. A questionnaire survey comprising of key questions including demographics, type of household, type of activities conducting indoor, time spent on activities indoor and outdoor in a microenvironment, preferred season of the year and mode of transport commuting to different areas was administered to the study participants. In addition, diaries were used to get information on daily activity time pattern for seven (7) days. Completion of questionnaire were based on interviews with the study participants while diaries were self-administered by the participants daily over seven days. Results In this study, a total of 130 participants aged 18-35 and 36-75 years were included. Approximately 33% and 67% of the respondents were < 35 years and >35 years, respectively. This suggests that most of the households are headed by adults outside the youth age category. About 30 houses were found to be erected using bricks while 100 houses were made of corrugated iron. About 75%, 14%, 8% and 2% of the study respondents were found to fall into the following race, black, coloured, Indian and white. Approximately (83% brick, 71% shacks) of the study respondents attained secondary education the remainder of the respondents attained primary education. The most performed activities inside brick type dwellings are sleeping (100%), cooking (77%), cleaning (70%) and watching television (TV) (60%). While most performed activities indoors for shack dwellings are cleaning (87%), cooking (70%), sleeping (68%) and TV (37%). There is a high prevalence of none employed household heads at 53% for the brick dwelling and 63% for the shack dwellers. The average monthly income was found to be R4 304 and R3 650, for brick and shack type dwellings, respectively. Females were found to perform a larger proportion of indoor household activities than males. A total of 36% was spend on cooking and cleaning followed by 29% of the time watching TV in the brick type dwellings. For the brick dwellers spend 67% indoors and 33% outdoor while for the shack dwellers about 31% of the time is spend indoor. Conclusion: The study had hypothesised that females above 18 years old residing in low-income communities are likely to spend most of their time at home carrying out domestic duties compared to their male counterparts, who are expected to spend most of the time outside the residential spaces. Therefore, the hypothesis for this study is partially confirmed, meaning that women spend most of their time indoor performing household chores than males. It was also found that the time spent indoor is relatively lower than what is globally reported as known to be >80% of the time, people are said to be indoors. This implies that the variation on the socio-economic status and sub-population including country’s dynamic might be the biggest influencer of time-activity pattern. Data obtained from this study can be used to account variability in human health risk assessments and reduce uncertainty in the derived exposure dosage where time spent pattern is considered an important variable. Recommendations: ✓ Future studies may be carried out covering a larger population density to gain more detailed time activity patterns. ✓ This study focused on a low-income settlement which has different characteristics to semi-formal, rural, high tax yield settlements in South Africa. Therefore, a larger study focusing on different socio-economic classes need to be carried out to have a comprehensive time activity pattern dataset for South African population. ✓ The current project focused only on adult age group without considering vulnerable groups (toddlers, and elderly person) time activity pattern. An additional study focusing on children time activity pattern is required in order to gain an understanding on what activities children spend most time.
Adolescent health in rural South Africa: building an evidence-base to inform a health promotion intervention supporting healthier lifestyles
(University of the Witwatersrand, Johannesburg, 2024) Seabi, Tshegofatso Martha; Kahn, Kathleen; Wagner, Ryan G
Background Low- and middle-income countries (LMICs), including South Africa, face the persisting double burden of malnutrition, with undernutrition and overnutrition coexisting within the population. This issue is particularly pronounced among rural adolescents, who experience limited access to healthcare services, inadequate infrastructure, poverty, and a scarcity of nutritious foods. Addressing this double burden of malnutrition is essential for improving the health outcomes of rural adolescents and breaking the intergenerational cycle of malnutrition. Community health worker-led interventions have shown promise in promoting healthier lifestyles in this population, making it crucial to understand the feasibility and acceptability of such interventions. Aim This thesis aims to provide context-specific information on the changing distribution of Body Mass Index (BMI) and views on obesity among rural South African adolescents to inform the development of a targeted behaviour change intervention. Furthermore, it seeks to determine the feasibility, acceptability, and overall experience of implementing a complex intervention aimed at promoting healthier lifestyles in this population. Methods Using a mixed methods approach focusing on adolescents 12-20 years of age living in rural South Africa. This work is nested within the MRC/Wits rural public health and health transitions research unit (Agincourt) Health and Demographic Surveillance System, which is where the sample was drawn and provided explanatory variables such as SES. This work includes data from two studies with comparable measures, conducted in 2007 (n= 1309) and in 2018 (n=518), this study analysed comprehensive data on the prevalence and trends of BMI, including both undernutrition and overweight/obesity, among rural adolescents in 2007 and 2018. This was done through weight and height measures. Growth z-scores were used to determine stunting, underweight and overweight and overweight/obesity was generated using the 2007 WHO growth standards for adolescents aged up to 17 years and adult cut-offs of BMI of <=18.5 for underweight and =>30 kg/m2 for overweight and obese respectively for adolescents 18 to 20 years. Qualitative data was collected in the form of focus group discussions and in-depth interviews. Pre-intervention, three focus group discussions were held with male (n = 16) and female adolescents (n = 15) focusing on obesity to capture views, attitudes and perceptions surrounding obesity. Post-interventions, six focus group discussions were held with male and female adolescents. In-depth interviews were conducted with adolescents (n=20), parents (n=5) and CHWs (n=3), focusing on the feasibility and acceptability of the health promotion intervention. All qualitative data were analysed using inductive thematic analysis. Results This study found that there is a persistent double burden of malnutrition amongst rural adolescents. The pattern of underweight and overweight/obesity remains similar between 2007 and 2018, with an increase in overweight and obesity, and a decrease in underweight observed across different age and gender groups throughout this period. The prevalence of stunting and underweight, particularly in males in both 2007 and 2018 was substantial although lower in the later year. Adolescents expressed conflicting views of obesity, highlighting their knowledge of the cause and long-term consequences of obesity. In regard to the intervention, participants expressed support for the CHWs and the community-based intervention guided by them. The findings demonstrated the feasibility of providing the intervention to adolescents in a rural context, with modifications needed to ensure participant uptake, such as changes to the time and location. Responses from participants show how the intervention, which included dietary and quantity modifications, was acceptable to adolescents. The gathered information in this study serves as a foundation for developing a health promotion intervention tailored to the specific needs and circumstances of rural adolescents, considering both undernutrition and overweight and obesity. Conclusion This research provides valuable context-specific insights into the burden of malnutrition and perceptions of obesity among rural South African adolescents, considering the complexities of the double burden of malnutrition. The findings contribute to the development of tailored health promotion interventions that address both undernutrition and overweight/obesity in this population. Understanding the feasibility and acceptability of such interventions is vital for successful implementation and sustainability in rural communities.
Assessing the potential interaction between CBD and TBR1 CBD and T-box domain
(University of the Witwatersrand, Johannesburg, 2024) Blignaut, Chanel; Sylvia, Fanucchi; Adeyemi, Samson
In 2020, Cannabidiol (CBD) emerged as the most commonly used recreational substance among pregnant women and was perceived as a natural and safer option for alleviating pregnancy- related symptoms, yet its potential effects on foetal neurodevelopment remain uncertain. With varied results from existing literature on the association between prenatal cannabis use and Autism Spectrum Disorder (ASD) development, this study focuses on filling these knowledge gaps. It investigates the potential interaction of CBD with the T-box domain of TBR1, a transcription factor implicated in ASD. CBD may cross the placenta and distribute throughout the developing foetal organs, including the brain, where it may interact with TBR1. This study's objective is to lay the groundwork for future research into the impact of CBD binding on TBR1 functionality, whose dysregulation is implicated in ASD. The study aims to use in vitro and in silico methods to identify and characterise the interaction between CBD and TBR1 T-box Domain. Initially, predictive models were utilised to determine the structure of the TBR1 T-box domain and its binding domains. Subsequently, the ADMET properties of CBD are assessed to determine its potential interaction with TBR1 T-box domain within the body. Through the optimisation of the TBR1 T-box domain and CBD structures, induced fit docking and molecular dynamics simulations, the study aims to predict the potential interaction sites, dynamics and stability of this interaction. The study confirms the computational results using in vitro methodologies. After expressing and purifying the TBR1 T-box domain, a pull-down assay (PDA), thermal shift assay (TSA) and Time-resolved Fourier-transformed infrared spectroscopy (TR-FTIR) are used to evaluate the potential binding, stability and physiochemical properties of the interaction. Computational analysis, using Maestro Schrödinger Induced Fit Protocol, predicts that CBD binds stably within a hydrophobic pocket of TBR1 T-box domain, away from its DNA-interacting residues. Pose 2 and 3 from molecular docking shows the highest binding affinity and molecular dynamics simulations, using Maestro Schrödinger Desmond Molecular Dynamics System, reveal that the TBR1 T-box domain stabilises upon interaction with CBD. Specifically, the interaction is facilitated by hydrophobic interactions and hydrogen bond formation with residues Ser238, Pro335, Thr360, Glu363 and Asn240. Experimental validation through PDA and TSA provided inconclusive results, but TR-FTIR confirmed the dynamic nature of the CBD-TBR1 interaction, characterised by time-dependent spectral changes. While the results do not directly indicate an impact of CBD on TBR1 functionality, further DNA binding studies are necessary for confirmation. This study suggests caution in using CBD during pregnancy due to its complex and largely unexplored interaction with TBR1, underscoring the need for more comprehensive research to conclusively understand its influence on neurodevelopmental disorders and its therapeutic potential
Association between serum zinc level and dynamics of Group B Streptococcus colonisation among pregnant women in South Africa
(University of the Witwatersrand, Johannesburg, 2024) Dhar, Nisha; Madhi, Shabir A
Background Maternal colonisation by Group B Streptococcus (GBS) is a major risk factor for early onset invasive GBS disease among newborns. Zinc micronutrient plays a critical role in several biological processes that are essential to prevent bacterial colonisation and/or invasion. The aim of this study was to investigate the association of serum zinc levels with GBS rectovaginal new acquisition and clearance from 20 to 37+ weeks gestation in pregnant women. Methods Vaginal and rectal GBS colonisation was determined at 20–25 weeks (visit-1), followed by 3 subsequent visits at 5–6 weeks intervals, until 37–40 weeks gestation (visit-4). Serum was collected at visit-1 and visit-4 and serum zinc was estimated by inductively coupled plasma mass spectrometry. “New acquisition” group was defined as participants for whom GBS culture was negative at visit-1 and acquired GBS in one of the subsequent visits. Participants not colonised with GBS at any visits were categorized as GBS “persistently uncolonised”. Participants who remained colonised throughout all study visits were defined as “persistently colonised” group. GBS “clearance group” included participants who were colonised at enrolment (visit-1) and in whom GBS colonisation cleared by last visit (visit-4). Results Participants in persistently un-colonised group had significantly higher zinc geometric mean concentration (GMC) at visit-1 compared with those who had new acquisition (20.18 µmol/L; 95%CI 17.99-22.64 vs 13.68 µmol/L; 95%CI 12.59-14.87, p=0.03). Higher zinc concentration in the persistently un-colonised group when compared with new acquisition group was significantly associated with lower odds of GBS rectovaginal acquisition [Odds ratio (OR) 0.15, p=0.001]. The lowest zinc threshold significantly associated with 45% lower odds of new acquisition was ≥15 umol/L (27.2% in new acquisition vs 40.5% in persistently un-colonised; OR 0.55; 95%CI 0.31- 0.96; p=0.03). Furthermore, zinc concentration was higher among women in clearance group compared with those in persistently colonised group (20.03 µmol/L; 95%CI 16.54-24.27 vs 16.45 µmol/L; 95%CI 13.32-20.31, p=0.04). Conclusion There was an inverse association between serum zinc levels in pregnant women and odds of GBS acquisition in those not initially colonised. Zinc supplementation in early pregnancy could reduce risk of invasive GBS disease in their newborns
Attrition in the dental therapy profession: an exploration of the contributing factors
(University of the Witwatersrand, Johannesburg, 2024) Sodo, Pumla Pamella; Jewett, Sara
Background: A new type of oral health profession called dental therapy was introduced to address the growing need for affordable and accessible oral healthcare services, especially among marginalised communities. Extensive global research has demonstrated that dental therapists provide cost-effective and high-quality services, effectively addressing the issue of limited access to basic oral health services. The introduction of dental therapy into the South African healthcare system took place in 1977, however, disparities in accessing basic oral healthcare persist, particularly among some population groups where the highest prevalence of oral diseases has been reported. Despite being established over four decades ago, the number of registered dental therapists remains low, and there have been reports of attrition within this professional group. This PhD aimed to explore the factors contributing to attrition in the dental therapy profession. The first objective was to determine South African dental therapists' attrition rate and demographic profile over 42 years (1977-2019). The second objective explored factors contributing to attrition, while the third objective explored the applicability of the Hertzberg Two-Factor Theory in the context of dental therapy attrition in South Africa. Methods: This was a concurrent mixed methods study, involving registered graduate dental therapists, former dental therapists, and key stakeholders. The conceptual framework that guided the study was derived from Hertzberg's Two-Factor Theory. Data sources included the HPCSA registry and primary data collected using a quantitative survey investigating job satisfaction and intention to leave among registered graduate dental therapists and qualitative in-depth interviews with former dental therapists and key stakeholders to gain insights into their perspectives on attrition in the dental therapy profession. The attrition rate was determined by using the formula (Attrition Rate = Number of dental therapists who left the profession divided by the total number of dental therapists registered during the period of interest, multiplied by 100). Quantitative data was analysed in STATA version 15 using descriptive and inferential statistics, and qualitative data was analysed using thematic analysis. Findings: A total of 1232 dental therapists were registered with HPCSA over 42 years, with only 714 registered in 2019, two-thirds of whom were Africans. The attrition rate over the 42 years was 40%, while it reduced to 9% during the 10 years from 2010 to 2019. Of the 200 registered dental therapists who took part in the survey, 74.5% being Africans, approximately 51.5% expressed their intention to leave the profession and a notable 69.5% reported job dissatisfaction. In logistic regression analysis, job satisfaction correlated positively with several factors, including qualification from UKZN (AOR= 2.28, CI: 1.06-4.91), post-graduation job availability (AOR=3.87, CI: 1.73-8.69), awareness of postgraduate opportunities (AOR=2.28, CI: 1.05-4.96), and feeling valued (AOR= 6.91, CI: 1.45-26.36). Conversely, job satisfaction was negatively associated with becoming aware of the scope of work only after enrolment (AOR= 0.31, CI: 0.21-0.81). Job satisfaction was inversely correlated with the intention to leave; satisfied individuals had significantly lower odds of intending to leave (AOR= 0.25, CI: 0.11-0.57). In-depth interviews with 14 former dental therapists identified diverse reasons for enrolling in dental therapy and a shared enthusiasm for the dental therapy profession. Most reasons they cited for attrition, such as inadequate remuneration, job scarcity, poor working conditions, lack of career advancement opportunities, and policy implementation gaps aligned with Herzberg's Two-Factor Theory. One novel factor contributing to attrition not covered by the theory was a lack of professional identity. The 12 key stakeholders who were interviewed echoed similar factors contributing to the attrition of dental therapists. To address limitations in moving from a description of factors to recommendations on how to address system-level challenges, I adapted a framework that is a combination of Herzberg's Two-Factor Theory and the Human Resources for Health System Development framework. This new framework addresses multifaceted issues affecting dental therapists, covering production, deployment, and retention. Conclusion: This study sheds light on challenges within South Africa's dental therapy profession, highlighting their profound implications for both the profession and the broader healthcare system. Despite comparable attrition rates to other mid-level health professionals, there were alarmingly high job dissatisfaction levels and intentions to leave the profession, demanding immediate attention and intervention. Identifying key factors contributing to attrition and the novel insight into the lack of professional identity collectively highlight the multifaceted nature of the issue. To address these challenges, embracing a comprehensive human resource retention framework is imperative. This study emphasizes the urgent need for proactive measures to ensure the sustainability and contentment of dental therapists, ultimately benefiting the healthcare system and the communities it serves. Addressing these factors will lead to increased retention rates and improved access to basic oral health services nationwide
Bayesian spatio-temporal analysis of malaria prevalence in children aged 2-10 years between 2000-2015 in Gabon
(2024) Mougeni, Fabrice Lotola
Abstract Background: In Gabon malaria still threatens the health of children and the country’s economy. In order to contribute in the estimation of malaria burden, in the endemic risk classification, and help in the design of the effective intervention, it is necessary to identify hot spots and cold spots, and to provide policy makers with good estimates of malaria prevalence at the national level with appropriate methods. It is also important, to understand, at a small spatial scale, how some factors are affecting the variation of malaria prevalence. This includes mainly geo-climatic factors, since malaria is related the meteorological conditions. This study focused on the effect of space and time in the distribution of malaria prevalence, and the effect of ecological variables in its variation for children between 2-10 years of age living in Gabon. Method: This study used successive cross-sectional data carried out in four time points: 2000, 2005, 2010, and 2015, using a stratified two-stage sampling method. The survey data provided information on malaria prevalence for children aged 2-10 years, and cluster-level ecological variables. Descriptive analysis such as the mean of the prevalence and the covariates with their standard deviation, on average, overtime, by province and type of residence was carried out, followed by more advanced models for the estimation of the prevalence. Considering the weighting scheme, the prevalence was obtained via the space and time Horvitz and Thompson estimator. This was then smoothed using the Besage York Mollié (BYM) model with space-time interaction, to reduce uncertainty due to the small area. The spatial autocorrelation was determined using the Moran’s I index, and hot spots with the local statistic Getis-Ord General Gi. The relationship between malaria prevalence and predictors was analyzed nationally. Ordinary Least squared (OLS) was used to see if the covariates can explain the spatial autocorrelation observed in the prevalence, Geographically Weighted Regression (GWR) or Spatial Varying Coefficient (SVC) to evaluate if the relationship between prevalence-covariates was not varying by location. Spatio-temporal model for OLS (SPTOLS) was used to account for the effect of time and space, and Geo-Additive Model (GAM) for considering the non-linear relationships. Lastly, Spatial Lag Model (SLM), Spatial Durbin Error Model (SDEM) or Spatial Error Model (SEM), were used for identifying the spillover effects. These were implemented in the Integrated Nested Laplace Approximation (INLA) using Stochastic Partial Differential Equation approach (SPDE). The different methods were compared to find the best one fitting well the data by using the DIC. Results: In total, 336 clusters were used, with 153 (46%), and 183 (54%) in rural and urban areas, respectively. On average, Estuaire province has the highest prevalence, followed by Moyen-Ogooue and Woleu-Ntem, 29% (±16%), 22% (±13%), 21% (±10%), respectively before the estimation using the smooth space-time model with sampling design. On average, after using the space-time smoothing model and the sample design, it was found that the prevalence decreased with year, and then showed a rebound from 2010. The highest value of the prevalence overtime was 46% in the Estuaire province in the year 2000 and the lowest value overtime was 6% in Ogooue-Maritime province in the year 2010. However, the effect of year was not significant. When the weight scheme was introduced, the variance of the estimate was reduced, and the contribution of the space in the variation of malaria prevalence was 46% during 2015. A strong spatial autocorrelation of the prevalence was found. Hot spots changed in magnitude by space and time, often in the north-west and the western part of the country. Cold spots were found mostly in the southern part. The spatial effect became almost null after 290 km (95% Credible Interval (CI): 230;360). The model including only the ecological variables was better in reducing the spatial variation. Using the SDEM, it was clearly seen how the prevalence can be influenced by the change of some risk factors in the nearby clusters or in the same cluster. The increase of malaria prevalence in a cluster was slightly and significantly associated with one-unit increase of: wet days (3%, 95% CI: [1%, 5%]) in the same cluster, and mean temperature (2%, 95% CI: [1%, 3%]) in the nearby clusters. It decreased slightly and significantly with a one-unit increase of day land surface (-2%, 95% CI: [-2%, -1%]) in the same cluster, but only slightly in the nearby clusters (< 1%). For a particular cluster, malaria prevalence decreased (-21%, 95% CI: [-40%, -5%]) greatly with the Insecticide Treated Bed Nets (ITNs) coverage increases in the nearby clusters. In contrast to GAM using SDEM for ITNs coverage only, the relationship between malaria revalence and ITNs coverage was clearly non-linear decreasing after 20% of coverage. Overall, malaria prevalence had non-linear relationship with mean temperature, night land surface temperature, enhanced vegetation index and rainfall. Conclusion: Substantial progress has been made to slow down the spread of malaria in Gabon. However, malaria prevalence is still high, with important spatial variation and hotspots in its distribution. The distribution of hot spots was showing some changes overtime in the cluster of households. Including the spatial effect allowed to obtain more accurate estimate of the prevalence, hence a better estimation of the clinical burden of P.falciparum. This can allow a better allocation of resources. From our findings, results may apply in two aspects: Firstly, in research focused on estimation in malaria. Such research trying to obtain an estimation of malaria outcomes, such as incidence, in different areas are encouraged to check on the spatial or spatio-temporal component in their estimation based on small area estimation with Bayesian approach due to the small level of unit to obtain more accurate estimate. Secondly, in strategies to reduce the prevalence. It is necessary to find strategies to increase, at the cluster of households level, the ITNs coverage to at least 20%, by taking into account some ecological variables implied in the decrease of the prevalence and to improve access to all health care interventions in the rural areas throughout the country. Monitoring the vector control intervention and those ecological variables can contribute to strengthen the action of interventions in public health, because of the spillover effect, which can spread the benefit of intervention over long distance to reach several areas not targeted in the neighborhood. This effect contributes in the cost-effectiveness of the interventions. The national direction of meteorology (DGM) and the NMCP need to work together to mitigate or control adverse climatic change effect on malaria if possible by developing early warning system for malaria. These results can be considered as a baseline for future surveys investigating the malaria distribution in Gabon and elsewhere.
Breast cancer survival to 5 years among young (<40 years) women in the sub-saharan African breast cancer-disparities in outcome (ABC-DO) cohort study
(2024) Abioye, Oyepeju F.
Introduction: Breast cancer remains a key global health challenge, accounting for most prevalent cause of cancer-related deaths worldwide. The impact of age at diagnosis on breast cancer survival has not been extensively investigated within the African context. Therefore, this study’s objectives were to estimate the breast cancer survival time among women 40 years) women in the ABC-DO Cohort Study in SSA. Methods: Secondary data analysis of breast cancer patients from the multi-country ABC-DO Prospective Cohort Study of 5 African countries was carried out. Baseline characteristics of study participants were summarized using descriptive statistics. Kaplan Meier curves were generated to evaluate breast cancer survival time by age group “<40 years, 40-64 years, 65+ years”. With the aid of Cox Multivariate Regression Modelling, factors correlated with a 5-year survival differential between younger and older women were investigated and Hazard Ratios were calculated adjusting for confounders. Results: This study had a total number of 2158 participants, 462 (21.41%) were <40 years at diagnosis, 1314 were between 40-64years (60.89%), while 382 patients were 65 years and above (17.70%). A total of 1211 deaths were recorded at 5 years. The total time at risk and incidence rate at 5 years was 6086.73 person years and 33 per 100 women respectively. The lowest overall survival at 5 years was found among women <40 years (33.46%; CI = 0.28-0.38), followed by women aged 65 years+ (37.63%; CI = 0.32-0.42), and highest overall survival was among women in the 40-64 years age group (42.66%; CI=0.39-0.45). For each country, the 5-year probability of survival was higher among women aged 40-64 compared to women under 40. On Cox multivariate analysis, a 20% rise in mortality was reported among women < 40 years (aHR 1.20; 95% CI= 1.03- 1.36) compared to women between 40-64 years in the final model, at p<0.05. The variables significantly associated with 5-year survival differential between younger and older women were: HIV status, Residence, and Stage at Diagnosis. Conclusion: This study reports that breast cancer survival among women in sub-Saharan Africa is age-specific, with lower 5-year overall and country-specific survival among women < 40 years in comparison to older women. Factors associated with lower survival include stage at diagnosis, HIV status, and area of residence. Young women (<40 years) in SSA remain at risk of increased mortality from breast cancer, hence there is an urgent need for targeted strategies to achieve a more favorable stage at diagnosis and improved survival in this populace.
Characterisation of emission and exposure to diesel engine exhaust from trackless mobile machinery in underground South African Platinum Mines: Evaluating strategies to prevent and control exposure
(University of the Witwatersrand, Johannesburg, 2024) Manyike-Modau, Amukelani Portia; Brouwer, Derk
Background: Mining remains one of the major economic drivers in South Africa, as is evident through continued focus on long-term investments in mining and the mechanisation of mining operations. Mechanisation uses diesel-powered machinery; such machinery offers greater versatility than electric and battery-operated vehicles due to their ability to cover greater distances and move between different working sections (1). Diesel powered machines are most preferred because of their high energy efficiency and low carbon monoxide and carbon dioxide emissions compared to gasoline equipment (2). Using diesel-powered machines in mechanised mining has introduced a new risk to mine workers working in confined spaces underground. Diesel engine exhaust (DEE) can increase significantly due to wear or breakdown of the engine components and after-treatment systems. The impact on emissions varies depending on the engine type, age, and state of wear and tear (3). Significant evidence demonstrates a correlation between DEE exposure and respiratory outcomes in mine workers. DEE is a known carcinogen. In 2012, the International Agency for Research on Cancer (IARC) classified DEE as being carcinogenic to humans (class I) when inhaled, based on sufficient evidence that exposure is associated with an increased risk for lung cancer (4). There has been an incredible drive to manage diesel Particulate matter (DPM) in the South African mining industry (SAMI). The approach, however, has been focused on monitoring personal exposure to DPM rather than a multifaceted approach that includes eliminating or reducing the pollutant at the source. Efforts should be made to ensure that management plans for engineered solutions and risk-based approaches are in place when monitoring DPM (5). As a result, research in the mining domain has focused on developing integrated control strategies/solutions to prevent exposure to diesel engine exhaust. South Africa shares the same concern with other countries regarding the DPM challenges in mining operations. The South African legal framework requires the employer to conduct a risk assessment and implement measures to prevent employees from overexposure to harmful airborne pollutants (MHSA 1996). Therefore, without local guidelines and regulations, SAMI can use the available scientific knowledge to control the exposure of DPM to employees and to ensure continuous monitoring of employees while working at the mines. Currently, no specific systems guide sets standards or limits for personal or occupational exposure or tailpipe emissions of DPM (6,7). Further, even though enough knowledge is The Occupational Cancer Research Centre Report published in 2017 presented different control strategies for DPM following the hierarchy of control principles (8). These ranged from the proactive (most effective) to reactive (less effective) controls and included the following controls: elimination using alternative energy such as electric or battery-powered machines, substitution such as replacing, repowering, or engine rebuilds, and this would typically include retrofitting the engines with engine after-treatment systems; Engineering controls which may include retrofitting the engines with after-treatment technologies, improving general ventilation systems, idling technologies, installation of protective cabs; Administrative controls which may include preventative maintenance, idling policies, operator training and planned schedule for the site such as planning the number of machines required to operate in a working place; and lastly the use of personal protective equipment such as respirators. These controlscan be implemented in a multifaceted approach to reduce or prevent employees from being overly exposed (3,8,9). Diesel emission is a complex mixture and may require multiple control strategies to minimise employee exposure. In the study conducted by Bugarski et al, 2009, they highlighted different monitoring and control strategies ranging from emissions monitoring, including undiluted emissions measurements, i.e., Both ‘tailpipe output’ and ‘engine out’ (upstream of after- treatment systems), and the installation of after-treatment strategies and higher tier standard engine emissions. The control strategies can help identify and distinguish between engine maintenance issues and emission control device failures and assist in estimating ventilation requirements (10). In addition, in a study by Hines in 2019, significant improvements were achieved in reducing tailpipe emissions (reduction at source) by implementing an emission- based maintenance (EBM) program. This has resulted in a reduction of Carbon Monoxide (CO) by more than 80% and DPM by more than 47% on personal exposure, showing the direct impact the EBM has on reducing exposure of DPM to employees working underground. The study successfully reduced tailpipe emissions by introducing the EBM program at the mines. Further, fuel usage was also reduced by 7-20%, showing that when machines are well maintained, there are improvements in efficiencies and even utilisation and availability of machines for production (11). Objective: The overarching aim of the research project was to determine the characteristics of diesel engine exhaust emissions at the source (aerodynamic size fractions) and evaluate how maintenance, maintenance plus installation of diesel particulate filters (DPF), and ventilation will impact the levels of DEE at the source and in the workplace. Methods: A quantitative, quasi-experimental study, designed with an intervention component, was conducted in two Platinum underground mines in South Africa. DEE was measured at the source, and DPM was personally exposed to employees. DPM dispersion modelling was conducted underground, and different control strategies were evaluated to determine their role in reducing the pollutant underground. Results: The concentration of median particles significantly decreased post the interventions, achieving an efficacy of 90-96% and 20-40% (p-value=0.001) for the machines that underwent maintenance plus installation of the DPF and machines that underwent maintenance only, respectively. Most particles emitted were in the ultrafine aerodynamic range, with a diameter between ≥0.01<0.1μm and an aerodynamic fine size of ≥0.1<1μm. Conclusion: A combination of control strategies (maintenance, retrofitting of machines with DPF, and ventilation) has shown great potential to reduce DEE in underground mines. Therefore, focused effort is required to implement integrated strategies to prevent or minimise exposure to DEE. Future studies to link dispersion models with real-time monitors are recommended to improve DEE's risk-based management
Characteristics of clients presenting for substance abuse treatment at cosup centresin the City of Tshwane
(2024) Manyane, Tabea Thama
Background: Substance abuse is a growing public health challenge in South Africa. It contributes significantly to the burden of disease. Integrated treatment approaches are required to address the substance abuse problem. The aim of this study was to determine the of risk of harm associated with substance use in subjects enrolled in the community-oriented substance use program (COSUP) in the City of Tshwane, South Africa, using the World Health Organization's Alcohol, Smoking and Substance Involvement Screening Test (ASSIST) tool and determine the demographic characteristics that might be associated with the changes in the ASSIST risk scores and the levels of risk of harm in those subjects. Methodology: A cross-sectional study design was used to retrospectively analyze secondary data collected from subjects enrolled into COSUP at time of enrolment and three-months follow-up from time of enrolment. Descriptive statistics were used to analyze the demographic characteristics. Univariate and multivariate logistic regression analyses of moderate- to high-risk opioid use in relation to demographic characteristics were done. Results: Most subjects were males (91.2%), single (79.8%), black (85.6%) and they were relatively young (median age 31+6.4 years). The high level of risk was found with the use of opioids (74.5%, 607/805), cannabis (28.8%, 232/805), and tobacco (16.1%, 130/805). Moderate levels of risk were found with tobacco (63,9%, 514/805), cannabis (25.6%, 206/805) and opioids (5.1%, 41/805). Moderate and high level of risk was found to be more in males (p=0.03) and in the black race (p=0.02). Multivariate analysis found moderate- to high-risk of opioid use to be positively associated with being married (adjusted odds ratio (aOR) 11.90, 95% confidence interval (CI) 1.30 – 108.20). Conclusion: Hazardous and harmful use of substances was found among users of opioids, cannabis and tobacco. Screening and harm reduction treatment interventions for substance use should be integrated within primary health care. Further research on the perceptions of substance users about harm reduction treatment interventions is required.
Community-orientated primary health care: Exploring the interface between community health workers, the healthcare system and communities in South Africa
(University of the Witwatersrand, Johannesburg, 2024) Malatji, Hlologelo; Goudge, Jane; Griffiths, Frances
Background: To achieve universal health coverage, low and middle income countries (LMICs) are extending primary health care (PHC) services using community health worker (CHW) programmes. However, CHWs are marginalized within the healthcare system. Community-orientated primary health care (COPC) and supportive supervision are two interventions being used to strengthen CHW programmes. Primary aim: To understand whether and how the COPC and supportive supervision approaches strengthen CHW programmes in South Africa. Methods: Data was collected between 2016 and 2019 using qualitative methods in nine PHC facilities in rural and semi-urban areas of Mpumalanga and Gauteng provinces, South Africa. Purposive and snowball sampling techniques were used to recruit participants. The participants included: CHWs, supervisors, facility staff members and community members. Data was collected using focus group discussions, individual interviews and observations, and was analysed thematically. Findings: In line with the COPC approach, there were efforts to engage communities in the implementation of the CHW programmes but community members prioritised other challenges such as lack of housing and running water. In some facilities, in-service training increased CHWs knowledge and skills but challenges such as lack of supervision, lack of resources and outsourced employment without benefits demotivated the CHWs (Paper 1 / Objective 1, Published). In response to challenges, in the semi-urban sites, CHWs unionised to present their grievances to government. This resulted in an increase in stipend but not permanent government employment. During the height of the COVID-19 pandemic, when decision- makers recognised the essential role of CHWs higher remuneration was secured. CHWs in rural areas were not active in demanding permanent employment (Paper 2 / Objective 2, Published). Supportive supervision provided by a nurse mentor over 14 months, (1) trained CHWs and their supervisors resulting in increased knowledge and new skills, (2) addressed their fears of learning and failing and (3) established operational systems to address inefficiencies in CHW core activities (household registration and medication delivery). The intervention was disrupted by union activities. The communities’ demonstrated little interest in the functioning of CHW programmes (Paper/ Objective 3, Published). Conclusion: Both the COPC approach and supportive supervision can reduce marginalisation of CHW within the health system
Cost utility analysis of long acting muscarinic antagonists (LAMAs) as an alternative to long acting beta agonists (labas) for treatment of severe COPD in the South African public sector
(2024) Thompson, Peggy
Objective- The study purposed to estimate the cost-effectiveness of Tiotropium, compared with Salmeterol and Indacaterol for chronic obstructive pulmonary disease (COPD) patients within the South African public sector. Methods- A global Markov model was adapted for the local setting and developed in Microsoft Excel. Transition probabilities and data on costs, resource use and effectiveness were obtained from literature. Outcomes were calculated for 3-years in the base case, then extrapolated over a 10-year and lifetime time horizon. A 5% discounting rate was applied according to local guidelines. Cost-effectiveness was estimated as the incremental cost per quality adjusted life year (QALY). One-way and probabilistic sensitivity analyses were conducted to consider model uncertainty. Results- When compared with Indacaterol (300µg), Tiotropium was dominant (less costly and more effective) across all time horizons. Conversely, Tiotropium was not cost-effective when compared with Indacaterol (150µg) and dominated by Salmeterol over the 3- and 10-year time horizons. The resulting ICURs exceeded the estimated willingness to pay thresholds for all scenarios. The deterministic sensitivity analysis revealed the new intervention cost and utility for mild COPD impacted most on intervention cost effectiveness. Conclusion- Tiotropium was deemed not cost-effective at the proposed price, when compared to usual care for COPD. A price reduction should be considered, to determine the feasibility of displacing existing maintenance therapies. Indacaterol 150µg appeared more cost-effective at the current price and effectiveness demonstrated.
Determinants of mortality in children younger than five years admitted with severe acute malnutrition to three hospitals in Vhembe district, Limpopo
(2024) Fakudze, Dakalo
Background: In 2014, one-third of child deaths occurring in South African hospitals were attributed to severe acute malnutrition. This study sought to determine demographic, family, socio-economic, clinical, and case-management factors contributing to mortality in severely malnourished children younger than 5 years admitted to three hospitals in Vhembe district, Limpopo, South Africa. Methods: A retrospective record review of children aged 6 to 59 months admitted with severe acute malnutrition over 30 months was conducted. Bivariable and multivariable regression analyses of determinants of mortality were undertaken. Results: Two hundred and forty-five children with severe acute malnutrition were identified. Their median (interquartile [IQR]) age was 14 (10, 18) months. The overall mortality was 26.9% (66/245). Determinants of mortality, based on the multivariable analysis, included diarrhoea on presentation (odds ratio [OR]=3.34, 95% CI 1.38, 8.10); anaemia (OR=3.30, 95% CI 1.28, 8.50]); a raised CRP (OR=9.29, 95% CI 2.81, 30.76]); and hyponatraemia (OR=6.64, 95% CI 2.70, 16.31). HIV status and a diagnosis of shock were not significant determinants of mortality. Conclusion: Severe acute malnutrition mortality was high, particularly for a high middle-income country setting. Factors that may be amenable to intervention include better management of the presenting illness, particularly diarrhea, a focus on electrolyte imbalance correction, and treatment of anemia.
Determinants of sub-optimal glycaemic control among patients enrolled in a medicine dispensing programme in Kwazulu-Natal: A cohort study, 2018 – 2021
(University of the Witwatersrand, Johannesburg, 2023) Johnston, Leigh Clare
Background: In South Africa, type 2 diabetes mellitus (T2DM) is a growing public health problem, thus, by 2030, 50% of T2DM patients, receiving treatment, must achieve optimal glycaemic control (haemoglobin A1c (HbA1c) ≤7%). The CCMDD (Central Chronic Medicines Dispensing and Distribution) programme allows glycaemically-stable patients to collect their medication from community-based pick-up points. While the CCMDD is a large public health programme, there is a paucity in stakeholder’s knowledge of T2DM patients glycaemic control over time. We determined glycaemic control for CCMDD-enrolled T2DM patients in eThekwini, South Africa from 2018-2021, as well as the rate and predictors of becoming sub-optimally controlled. Methods: We performed a cohort study, linking HbA1c data from the National Health Laboratory Service to CCMDD-enrolled patients in eThekwini, South Africa from 2018–2021. We included patients optimally controlled at their baseline HbA1c, and having ≥1 repeat test available. We used Kaplan Meier analysis to assess survival rates and Cox regression to determine associations between time to sub-optimal control (HbA1c > 7%) and several factors. Adjusted hazard ratios (aHR), 95% confidence interval (95% CI), and p-values are reported. Results: Of 41145 T2DM patients enrolled in the CCMDD, 7960 (19%) had an available HbA1c result over the study period. A quarter of patients (2147/7960; 27%) were optimally controlled at their baseline HbA1c. Of those controlled at baseline, 695 (32%) patients had a repeat test available, with 35% (242/695) changing their status to sub-optimal control. Patients prescribed dual-therapy had a higher risk of sub-optimal glycaemic control (aHR: 1.503; 95% CI: 1.16–1.95; p-value=0.002) compared to those on monotherapy. HbA1c testing frequency per national guidelines (aHR: 0.46; 95% CI: 0.24–0.91; p-value=0.024) was associated with a lower hazard of sub-optimal glycaemic control. Conclusions: HbA1c monitoring, in line with testing frequency guidelines, is needed to flag sub- optimally controlled patients who become ineligible for CCMDD enrolment. Patients receiving dual-therapy may require special consideration. Addressing these shortfalls can assist planning and implementation to achieve 2030 targets.
Early life factors associated with childhood trajectories of violence among the birth to twenty- plus cohort in Soweto, South Africa
(University of the Witwatersrand, Johannesburg, 2024) Muchai, Lilian Njeri; Kagura, Juliana; Naicker, Sara
Introduction Violence against children has devastating and long-term negative consequences on individuals' and society's health, social and economic well-being. There is limited research on the life course experience of violence especially in Africa. This study aimed to identify sub-groups of physical & sexual violence victimization patterns separately in childhood, and evaluate early life factors predicting these violence trajectories. Methods This study used data from age 5 to 18 years from the ongoing prospective Birth to Twenty Plus cohort (Bt20+). Children within the Bt20+ cohort with data on physical and sexual violence in at least 2-time points between 5 and 18 years were included in the analyses. Group-based trajectory modelling was employed to identify groups of children with similar patterns of violence over time. Descriptive statistics was used to summarize study variables by violence trajectory group membership, while multivariable logistic regression was used to identify early life factors measured between birth and 5 years, associated with violence trajectory group membership. Results Two trajectory groups were identified for both physical and sexual violence victimization. For physical violence victimization, the majority of participants fell into the adolescent limited group (65.1%) and just over a third (34.9%) of the children were in the chronic increasing group. For sexual violence victimization, most participants fell into the adolescent limited group (74.1%, with a quarter in the late increasing (25.9%) group. Early life factors associated with a higher risk of chronic increasing physical violence victimization trajectory group membership, after adjusting for covariates, were being male (aOR 1.67, 95% CI 1.31; 2.10) and having a mother with at least secondary education compared to higher education (aOR 1.73, 95% CI 1.08; 2.76). In addition, residing in middle, compared to low, socioeconomic households (aOR 0.68, 95% CI 0.50; 0.92) was protective against membership in this group. Residing in high compared to low socioeconomic households, was the only early life factor with marginally significant (aOR 0.63, 95% CI 0.42; 0.95) association with membership in the late-increasing sexual violence victimization trajectory group, with those in better-off households less likely to experience sexual violence victimization with this pattern. Conclusion Children within the same community can follow different patterns of both physical and sexual violence victimization across childhood. Identification of early factors that predict membership to sub-groups of violence trajectories provides key violence prevention intervention points that can preempt or mitigate children’s exposure or experience of violence. Future research should explore a larger variety of early life factors proximal to the child as well as those more distal at the community and school levels
Educational programmes used in teaching nurses mechanical ventilation in adult intensive care units: a scoping review
(2024) Davis, Daniele Ruth
Introduction Mechanical ventilation is a common form of life support intervention and nurses are the key personnel in providing safe and specialized care to these patients. Their education determines whether patients receive optimal quality care and attain the best possible outcomes. Purpose: To identify the available evidence on invasive mechanical ventilation educational programmes developed for teaching all nurses working in adult intensive care units; regardless of their level of qualification or years of experience. It includes the content taught and the method of instruction used. Methods: Due to the breadth of the review topic, a scoping review methodology was considered appropriate and guided by The Joanna Briggs Institute (JBI) Scoping Review methodology. Eligibility criteria using the PCC framework, and relevant keywords and phrases originating from these criteria were used to search five databases in July and August 2022 (PubMed, EBSCO CINAHL, Wiley Online, Scopus and ProQuest). The Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR) guidelines were used to report the results. Results: Nine studies fulfilled the inclusion criteria for full review. Four studies were relevant to invasive mechanical ventilation; two studies were specifically related to ventilator associated pneumonia and one each on weaning, endotracheal tube cuff pressure management and the development of a programme for nurses transitioning into the intensive care unit. Conclusion: There is limited evidence of comprehensive educational programmes on invasive mechanical ventilation for all nurses working in the intensive care unit.
Efficacy of noise control measures at high noise zones from a copper mine in Zambia
(University of the Witwatersrand, Johannesburg, 2024) Nchimunya, Bbautu; Hayumbu, Patrick; Masekameni, Masilu Daniel
Noise exposure is a global problem, it is estimated that about 30 million workers in the United States of America (USA) are exposed to high noise levels while across Europe, 28% of the workers are exposed to high noise levels. Hazardous noise exposure is associated with a wide range of health effects that include noise induced hearing loss (NIHL), stress, poor concentration, communication difficulties and fatigue due to lack of sleep. The mining industry worldwide is struggling with hearing loss due to noise overexposure and in a copper mining set-up, the concentrator section is assumed to be among high noise zones exposing workers to noise above the occupational exposure limit (OEL) of 85 dB(A). This study aimed at evaluating the efficacy of noise control measures at various sections at Konkola Copper Mine concentrator section in Zambia. This quantitative cross-sectional study was conducted at Konkola Copper Mines (KCM) Konkola Business Unit (KBU) in Chililabombwe District in the Copperbelt Province of Zambia. A walk through survey was conducted to collect information to describe the operations, identify noise sources, understand noise release mechanisms and describe noise control measures. Quality control was achieved by triplicate noise measurement per location using an instrument with a valid annual calibration certificate. Raw data was pre-processed by cleaning to make it ideal for use. An ethical waiver W-CBP-230428-01 was granted as this study did not involve animal or human subjects but only area noise samples using CR: 172B SLM. The study identified the noise sources, described noise release mechanisms, described the noise controls and assessed the efficacy of noise controls in four sections within the concentrator of a copper mine in Zambia. Seventeen noise generating equipment were identified with about 53% of the equipment operated at the crushing section, 18% operated at the Flotation and Filtration section respectively and 11% at Milling section. A substantial portion (65%) of the identified noise sources in the concentrator are not housed, and among these, 36% are mobile in nature. It was also found that none of the noise areas were demarcated There are three types of noise controls (enclosure, silencer & HPD) that are in use at the concentrator and they fall in two categories of the hierarchy of controls (engineering & PPE). Out of the nine noise sources at the Crushing section, 56% (5 of the 9) utilized enclosure as control, 33% (3 of the 9) had HPDs as control and 11% (1 of the 9) source was installed with a silencer as a control. Enclosure is utilized to control noise from the two sources found in the Milling section while HPDs and enclosure are the noise control measures in use at both Flotation and Filtration sections of the concentrator. Enclosure is the most available control in the concentrator at 53%, followed by HPDs at 41%, and the least available is silencer at 6 %. About 76.5% (13) of the noise controls at the concentrator had efficacy strong enough to reduce noise levels to below the OEL while 23.5% (4) of the controls had weak efficacy that failed to reduce noise levels to below the OEL. This has prompted the need to strengthen efficacy in areas where controls were found to be weak. There is need to sustain controls that were found to be strong to maintain their efficacy. About 75% (3 of the 4) of the controls with lower efficacy were from the Crushing section while 25% (1 of the 4) was from Filtration section
Efficacy of water suppression method for controlling the emissions of submicron particles at a quarry, Boksburg, South Africa
(2024) Mkwanazi, D. D.
Background: Respiratory diseases has contributed 70% to worldwide occupational disease mortality in all industrial sectors since over a decade ago. Pneumoconioses occur as a result of accumulation of dust in the lungs. Silicosis, one of the most common forms of pneumoconioses, presents in three different forms namely acute, accelerated, and chronic silicosis. Quarrying and open cast mining are responsible for different workplace hazards including noise, trauma, vibration, ultraviolet radiation, and dust exposure, which may cause silicosis. Lung deposition of particulate matter depend on the particulate matter surface characteristics, aerodynamic size, and weight. Quarrying and stone crushing activities are associated with high levels of crystalline silica release. Water suppression has been proven to effectively control dust in mining and construction industries, but not enough attention has been paid on effects of water suppression on fine particulate matter. Purpose: To evaluate efficacy of water suppression as a dust control measure for submicron particles for the primary, secondary and tertiary treatment processes during the production of stone aggregates in a quarry. Methods: In this cross-sectional study data was collected using a Nanozen dust sampling device to monitor dust emissions in 0.300µm to 10.658µm bin sizes across 4 different sampling points namely primary, secondary, tertiary treatment area, and office complex at a quarry in Boksburg, South Africa. In the primary treatment area big rocks are crushed into 150mm smaller rock without dust suppression, the secondary area breaks them further into 57mm stones with water supperssion applied, and tertiary breaks them into 19mm and smaller stone products under further water suppression conditions. Primary treatment area and office complex were sampled as dry areas, while secondary and tertiary treatment areas were sampled as water suppression areas. Data was analysed based on mass and number concentrations for different bin sizes, and comparisons were made between dry and wet areas. The effect of water treatment (suppression) on submicron bin ranges (0.300-0.915µm) in terms of mass concentration and number concentration was analysed to determine its efficacy in reducing dust emissions in this range. Results: The total average mass concentration of 460.2 µg/m3 (±486.3) was emitted from the primary area without dust suppression with average of 2.22E+08 (±136958.7) number concentration. This was reduced to 6.02µg/m3 and 60.9 million (±552879) mass and number concentration respectively in secondary treatment area with water suppression. In tertiary area emissions were 10.52µg/m3 and 54.8 million particles/cm3 (±828126) respectively for mass and number concentrations following further water suppression, while in office area (no water suppression) 6.07µg/m3 and 44.4 million/cm3 mass and number concentrations were recorded respectively. Conclusions & Recommendations: Data showed reduction of emissions between primary and secondary area by 98.7% (mass concentration) and 72.5% (number concentration). Further treatment in tertiary treatment showed a further decrease in total average number concentration compared to secondary treatment. Emissions at the office block as a control site were consistent with emissions from secondary and tertiary treatment areas, demonstrating possible dispersion by wind. Water suppression was demonstrated to be effective against particle bin sizes larger than 1 micron, with progressively less effect on submicron particles as they became smaller. More research is recommended on suppression of submicron dust particulate matter emission and consideration of number concentration as a key dose matrix to determine exposure.
Estimating and predicting HIV risk using statistical and machine learning methods: a case study using the 2005 to 2015 Zimbabwe demographic health survey data
(2024) Makota, Rutendo Beauty Birri
Background: The 90–90–90 targets were launched by the Joint United Nations Programme on HIV/AIDS (UNAIDS) and partners with the aim to diagnose 90% of all HIV-positive persons, provide antiretroviral therapy (ART) for 90% of those diagnosed, and achieve viral suppression for 90% of those treated by 2020. In Zimbabwe, a population-based survey in 2016 reported that 74.2% of people living with HIV (PLHIV) aged 15–64 years knew their HIV status. Among the PLHIV who knew their status, 86.8% self-reported current use of Antiretroviral treatment (ART), with 86.5% of those who self-reported being virally suppressed. For these 90–90–90 targets to be met, prevalence and incidence rate estimates are crucial in understanding the current status of the HIV epidemic and determining whether the trends are improving to achieve the 2030 target. Ultimately, this will contribute to the achievement of Sustainable Development Goals 3 (SDG 3) and the broader goal of promoting sustainable development and eradicating poverty worldwide by 2030. Using data from household surveys, this thesis provides a unique statistical approach for estimating the incidence and prevalence of the Human Immunodeficiency Virus (HIV). To properly assess the efficacy of focused public health interventions and to appropriately forecast the HIV-related burden placed on healthcare systems, a comprehensive assessment of HIV incidence is essential. Targeting certain age groups with a high risk of infection is necessary to increase the effectiveness of public health interventions. To jointly estimate age-and-timedependent HIV incidence and diagnosis rates, the methodological focus of this thesis was on developing a comprehensive statistical framework for age-dependent HIV incidence estimates. Additionally, the risk of HIV infection was also evaluated using interval censoring methods and machine learning. Finally, geospatial modelling techniques were also utilised to determine the spatial patterns of HIV incidence at district levels and identify hot spots for HIV risk to guide policy. The main aim of this thesis was to estimate and predict HIV risk using statistical and machine learning methods. Study objectives: The study objectives of this thesis were: 1. To determine the effect of several drivers/factors of HIV infection on survival time over a decade in Zimbabwe, using current status data. 2. To determine common risk factors of HIV positivity in Zimbabwe and the prediction capability of machine learning models. 3. To estimate HIV incidence using the catalytic and Farrington models and to test the validity of these estimates at the national and sub-national levels. 4. To estimate the age- and time-dependent prevalence and HIV Force-of-infection (FOI) using current status data by comparing parametric, semi-parametric and non-parametric models; and determining which models best fit the data. 5. To investigate the HIV incidence hotspots in Zimbabwe by using geographicallyweighted regression. Methods: We performed secondary data analysis on cross-sectional data collected from the Zimbabwe Demographic Health Survey (ZDHS) from 2005 to 2015. Datasets from three Zimbabwe Demographic Health Survey HIV test results and adult interviews were merged, and records without an HIV test result were excluded from the analysis. The outcome variable was HIV status. Survey and cluster-adjusted logistic regression were used to determine variables for use in survival analysis with HIV status as the outcome variable. Covariates found significant in the logistic regression were used in survival analysis to determine the factors associated with HIV infection over the ten years. The data for the survival analysis was modelled assuming age at survey imputation (Model 1) and interval-censoring (Model 2). To determine the risk of HIV infection using machine learning methods, the prediction model was fit by adopting 80% of the data for learning/training and 20% for testing/prediction. Resampling was done using the stratified 5-fold cross-validation procedure repeatedly. The best algorithm was the one with the highest F1 score, which was then used to identify individuals with a higher likelihood of HIV infection. Considering that the proportion of those HIV negative and positive was imbalance with a ratio of 4.2:1, we applied resampling methods to handle the class imbalance. We performed the Synthetic Minority Over-sampling Technique (SMOTE) to balance the classes. We evaluated two alternative methods for predicting HIV incidence in Zimbabwe between 2005 and 2015. We estimated HIV incidence from seroprevalence data using the catalytic and Farrington-2-parameter models. These models were validated at the micro and macro levels using community-based cohort incidence and empirical estimates from UNAIDS EPP/SPECTRUM, respectively. To ascertain the age-time effects of HIV risk, we estimated the age- and time-dependent HIV FOI using current status data. Five generalised additive models were explored, ranging from linear, semi-parametric, non-parametric and nonproportional hazards additive models. The Akaike Information Criteria was used to select the best model. The best model was then used to estimate the age- and time-dependent HIV prevalence and force-of-infection. The OLS model was fitted for each survey year to determine the global relationship between HIV incidence and the significant covariates. The Moran's I spatial autocorrelation method was used to assess the spatial independence of residuals. The Getis-Ord Gi* statistic was used for Hotspot Analysis, which identifies statistically significant hot and cold spots using a set of weighted features. Interpolation maps of HIV incidence were created using Empirical Bayesian Kriging to produce smooth surfaces of HIV incidence for visualisation and data generation at the district level. The Multiscale Geographically Weighted Regression method was used to see if the relationship between HIV incidence and covariates varied by district. The software used in the thesis analysis included R software, STATA, Python, ArcGIS and WinBugs. Results: Model goodness of fit test based on the Cox-Snell residuals against the cumulative hazard indicated that the model with interval censoring was the best. On the contrary, the Akaike Information Criterion (AIC) indicated that the normal survival model was the best. Factors associated with a high risk of HIV infection were being female, the number of sexual partners, and having had an STI in the past year prior to the survey. The machine learning model indicated that the XGBoost model had better performance compared to the other 5 models for both the original data and SMOTE processed data. Identical variablesfor both sexes throughout the three survey years for predicting HIV status were: total lifetime number of sex partners, cohabitation duration (grouped), number of household members, age of household head, times away from home in last 12 months, beating justified and religion. The two most influential variable for both males and females were total lifetime number of sex partners and cohabitation duration (grouped). According to these findings, the catalytic model estimated a higher HIV incidence rate than the Farrington model. Compared to cohort estimates, the estimates were within the observed 95% confidence interval, with 88% and 75% agreement for the catalytic and Farrington models, respectively. The limits of agreement observed in the Bland-Altman plot were narrow for all plots, indicating that our model estimates were comparable to cohort estimates. Compared to UNAIDS estimates, the catalytic model predicted a progressive increase in HIV incidence for males throughout all survey years. Without a doubt, HIV incidence declined with each subsequent survey year for all models. Based on birth year cohort-specific prevalence, the female HIV prevalence peaks at approximately 29 years of age and then declines. Between 15 and 30 years, males have a lower cohort-specific prevalence than females. Male cohort-specific prevalence decreases marginally between ages 33 and 39, then peaks at age 40. In all age categories, the cohort-specific FOI is greater in females than males. Moreover, the cohortspecific HIV FOI peaked at age 22 for females and age 40 for males. A 18-year age gap between the male and female HIV FOI peaks was observed. Throughout the decade covered by this study, the Tsholotsho district remained a 99 % confidence hotspot. The impact of STI, condom use and being married on HIV incidence has been strong in the Eastern parts of Zimbabwe with Mashonaland Central, Mashonaland East and Manicaland provinces. From our findings from the Multiscale Geographically Weighted Regression (MGWR), we observed that Matabeleland North’s HIV incidence rates are driven by wealth index, multiple sex partners, STI and females with older partners. Conclusions: The difference between the results from the Cox-Snell residuals graphical method and the model estimates and AIC value may be due to inadequate methods to test the goodness-of-fit of interval-censored data. We concluded that Model 2 with interval-censoring gave better estimates due to its consistency with the published results from the literature. Even though we consider the interval-censoring model as the superior model with regard to our specific data, the method had its own set of limitations. Programmes targeted at HIV testing could use the machine learning approach to identify high-risk individuals. In addition to other risk reduction techniques, machine learning may aid in identifying those who might require Pre-exposure prophylaxis. Based on our results, older men and younger women resembled patterns of higher HIV prevalence and force-of-infection than younger men and older women. This could be an indication of age-disparate sexual relationships. Therefore, HIV prevention programmes should be targeted more at younger females and older males. Lastly, to improve programmatic and policy decisions in the national HIV response, we recommend the triangulation of multiple methods for incidence estimation and interpretation of results. Multiple estimating approaches should be considered to reduce uncertainty in the estimations from various models. The study spread the message that various factors differ from district to district and over time. The study's findings could be useful to policymakersin terms of resource allocation in the context of public health programs. The findings of this study also highlight the importance of focusing on districts like Tsholotsho, which have consistently had a high HIV burden over time. The main strength of this study is dependent on the quality of the data obtained from the surveys. These data were derived from population-based surveys, which provide more reliable and robust data. Another strength of this study was that we did not restrict our analysis to one method; however, we had the opportunity to determine the risk and incidence of HIV by exploring different methodologies. However, the limited number of variables accessible to us for this study constituted one of its drawbacks. We could not determine the impact of variables including viral load, health care spending, HIV- risk groups, and other HIV-related interventions. Additionally, there were missing values in the data, which required making assumptions about their unpredictability and utilising imputation methods that are inherently flawed. Last but not least, a number of the variables were self-reported and, as a result, were vulnerable to recall bias and social desirability bias.