South African Medical Research Council (SAMRC) Repository
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Accelerated epigenetic aging in adolescents living with HIV is associated with altered development of brain structures
No full textWe recently demonstrated that adolescents perinatally infected with HIV-1 (PHIV+) have accelerated aging as measured by a highly accurate epigenetic biomarker of aging known as the epigenetic clock. However, whether epigenetic age acceleration in PHIV+ impacts brain development at the macro- and microstructural levels of brain anatomy has not been studied. We report on a cross-sectional study of PHIV+ enrolled in the Cape Town Adolescent Antiretroviral Cohort (CTAAC). The Illumina Infinium Methylation EPIC array was used to generate DNA methylation data from the blood samples of 180 PHIV+ aged 9 to 12 years. The epigenetic clock software and method was used to estimate two measures, epigenetic age acceleration (AgeAccelerationResidual) and extrinsic epigenetic age acceleration (EEAA). Each participant underwent T1 structural magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI). In order to investigate the associations of chronological age, sex, epigenetic age acceleration and treatment variables (CNS penetration effectiveness score (CPE)) of antiretroviral regimen on brain structure in PHIV+, we developed stepwise multiple regression models in R (version 3.4.3, 2017) including grey and white matter volumes, cortical thickness, cortical surface area and DTI measures of white matter microstructural integrity.
The mean DNAm age (16.01 years) of the participants was higher than their mean chronological age (10.77 years). Epigenetic age acceleration contributed more to regional alterations of brain volumes, cortical thickness, cortical surface areas and neuronal microstructure than chronological age, in a range of regions. CPE positively contributed to volume of the brain stem. Understanding the drivers of epigenetic age acceleration could lead to valuable insights into structural brain alterations, and the persistence of neurocognitive disorders in seen in PHIV+ .Funding for CTAAC was provided by R01-HD074051 (HJZ) and SA MRC. HJZ and DJS are supported by the South African Medical Research Council
The legal feasibility of adopting a sugar-sweetened beverage tax in seven sub-Saharan African countries
No full textBackground: A number of countries have adopted sugar-sweetened beverage taxes to prevent non-communicable diseases but there is variance in the structures and rates of the taxes. As interventions, sugar-sweetened beverage taxes could be cost-effective but must be compliant with existing legal and taxation systems.
Objectives: To assess the legal feasibility of introducing or strengthening taxation laws related to sugar-sweetened beverages, for prevention of non-communicable diseases in seven countries: Botswana, Kenya, Namibia, Rwanda, Tanzania, Uganda and Zambia.
Methods: We assessed the legal feasibility of adopting four types of sugar-sweetened beverage tax formulations in each of the seven countries, using the novel FELIP framework. We conducted a desk-based review of the legal system related to sugar-sweetened beverage taxation and assessed the barriers to, and facilitators and legal feasibility of, introducing each of the selected formulations by considering the existing laws, laws related to impacted sectors, legal infrastructure, and processes involved in adopting laws.
Results: Six countries had legal mandates to prevent non-communicable diseases and protect the health of citizens. As of 2019, all countries had excise tax legislation. Five countries levied excise taxes on all soft drinks, but most did not exclusively target sugar-sweetened beverages, and taxation rates were well below the World Health Organization's recommended 20%. In Uganda and Kenya, agricultural or HIV-related levies offered alternative mechanisms to disincentivise consumption of sugar-sweetened beverages without the introduction of new taxes. Nutrition-labelling laws in all countries made it feasible to adopt taxes linked to the sugar content of beverages, but there were lacunas in existing infrastructure for more sophisticated taxation structures.
Conclusion: Sugar-sweetened beverage taxes are legally feasible in all seven countries Existing laws provide a means to implement taxes as a public health intervention.This research was supported by the International Development Research Center grant [#108648-001]. KH, SAK, AE are supported by South African Medical Research Council/Centre for Health Economics and Decision Science–PRICELESS SA, University of Witwatersrand School of Public Health, Faculty of Health Sciences, Johannesburg South Africa [D1305910-03]
Strengthening prevention of nutrition-related non- communicable diseases through sugar-sweetened beverages tax in Rwanda: A policy landscape analysis
No full textBackground: Food and beverages high in sugar are recognized to be among the major risk factors for nutrition-related non-communicable diseases. The growing presence of ultra-processed food producers has resulted in shifts to diets that are associated with non-communicable diseases and which include sugar-sweetened beverages. Sugar-sweetened beverage taxation presents an opportunity to prevent non-communicable diseases but it comes with challenges.
Objectives: To describe the policy landscape, identify and analyse the facilitators of and barriers to strengthening taxation on sugar-sweetened beverages in Rwanda.
Methods: We conducted a desk-based policy analysis to assess the facilitators of and barriers to strengthening sugary beverage taxation policy. We consulted eight stakeholders to validate the findings of the desk review.
Results: Non-communicable diseases are recognized as a public health challenge in Government health and non-health policy documents. However, sugar intake is not explicitly identified as a risk factor for non-communicable diseases and existing policies do not clearly aim to reduce sugar consumption. The Rwandan Government's commitment to growing the local sugar industry and the substantial economic contribution of Rwandan beverage producers are potential barriers to fiscal policies aimed at reducing sugar consumption. However, the current 39% excise tax levied on all soft drinks could support the adoption of future sugar-sweetened beverage policies.
Conclusions: The landscape for strengthening a sugar-sweetened beverage tax in Rwanda is complex. The policy environment provides both facilitators of and impediments to strengthening the existing tax. A differential tax could be introduced by leveraging on the existing excise tax and linking it to the sugar content of beverages.This research was supported by the International Development Research Center grant [#108648-001]. KH, SAK, AE are supported by South African Medical Research Council/Centre for Health Economics and Decision Science – PRICELESS SA, University of Witwatersr and School of Public Health, Faculty of Health Sciences, Johannesburg South Africa [D1305910- 03]
Joint briefing on the status of the national vaccine rollout to public and private healthcare workers
No full textVaccine Webinar: NDOH, SAMRC, B4SA
Flexible modelling of risk factors on the incidence of pneumonia in young children in South Africa using piece-wise exponential additive mixed modelling
No full textIntroduction: Recurrent episodes of pneumonia are frequently modeled using extensions of the Cox proportional hazards model with the underlying assumption of time-constant relative risks measured by the hazard ratio. We aim to relax this assumption in a study on the effect of factors on the evolution of pneumonia incidence over time based on data from a South African birth cohort study, the Drakenstein child health study.
Methods: We describe and apply two models: a time-constant and a time-varying relative effects model in a piece-wise exponential additive mixed model's framework for recurrent events. A more complex model that fits in the same framework is applied to study the continuously measured seasonal effects.
Results: We find that several risk factors (male sex, preterm birth, low birthweight, lower socioeconomic status, lower maternal education and maternal cigarette smoking) have strong relative effects that are persistent across time. When time-varying effects are allowed in the model, HIV exposure status (HIV exposed & uninfected versus HIV unexposed) shows a strong relative effect for younger children, but this effect weakens as children grow older, with a null effect reached from about 15 months. Weight-for-length at birth shows a time increasing relative effect. We also find that children born in the summer have a much higher risk of pneumonia in the 3-to-8-month age period compared with children born in winter.
Conclusion: This work highlights the usefulness of flexible modelling tools in recurrent events models. It avoids stringent assumptions and allows estimation and visualization of absolute and relative risks over time of key factors associated with incidence of pneumonia in young children, providing new perspectives on the role of risk factors such HIV exposure
Network for Genomic Surveillance South Africa (NGS) SARS-COV-2 Sequencing update
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Report on weekly deaths in South Africa: Week 46
No full textThis report provides estimates of the weekly number of deaths of all persons in South Africa for epidemiological Week 46 of 2021, covering the period 14 - 20 November 2021
Report on weekly deaths in South Africa: Week 26
No full textThis report provides estimates of the weekly number of deaths of person 1+ years in South Africa for epidemiological Week 26 of 2021, covering the period 27 Jun - 3 Jul 2021
