Browsing by Author "Gibbon, Victoria E"

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    Assessing the accuracy of the zygoma for estimating ancestry using geometric morphometrics in a South African sample
    (2019) Tawha, Tafadzwa Primrose Rudo; Gibbon, Victoria E; Dinkele, Elizabeth; Mole, Calvin
    The large number of unidentified, decomposed and skeletonised remains found in South Africa (SA) necessitates relevant and reliable methods to assist in victim identification. Ancestry estimation from unknown skeletal remains is essential when reconstructing a demographic profile of a missing person. In the SA population, estimating ancestry is problematic as standards developed internationally rarely apply to the local, biologically heterogenous population. Craniofacial morphology is known to be ancestrally distinct and studies are yet to explore shape and size variation in the zygomatic bone of the SA population. The aim of this study was to assess ancestral variation in zygomatic shape and size in a SA population using three-dimensional geometric morphometric analyses. A sample of 158 individuals were analysed from Bantu-speaking (BA), European (EA) and Mixed Ancestral (MA) South African groups. Males were larger in size than females, but no size differences were observed between ancestral groups. Significant shape differences were observed between ancestral groups, while none were observed between males and females. BA and MA individuals had narrower, shorter and more anteriorly projecting zygomas than EA individuals. The zygoma was shown to accurately distinguish EA (84%) from BA (81%), and MA (80%) from EA (68%) individuals, but unreliably distinguished BA (60%) from MA (66%) individuals. This is likely correlated to the historical peopling of SA and historical forced racial classification. Age-related changes and antemortem tooth loss did not confound the ancestral variation in size, despite minor changes in zygomatic shape being associated with these two factors. These confounders did not impact ancestry estimation accuracies, further suggesting a minor impact on overall zygomatic shape. Furthermore, the patterning of ancestral variation in the zygoma revealed the need for further research to distinguish between the biologically heterogenous ancestral groups in SA.
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    Growth Analysis of Mixed Ancestry Infants Aged 0 – 18 months, South Africa
    (2022) Arendse, Liesl; Gibbon, Victoria E; Brits, Desiré; Lambert, Victoria
    Early life nutritional status and subsequent growth trajectory may impact adult health status later in life. In South Africa, children of mixed ancestry (MA, 1-10 years) have a significantly higher risk for stunting (according to WHO growth standards) compared to other population groups. Adults of MA have the second highest type II diabetes mellitus prevalence, and hypertension doubled between 2008-2016. Insight into healthy MA infant growth may help to explain, in part, this pattern of adult-onset NCDs. This study aimed to document healthy MA infant growth, against the WHO growth standards, in a 0 – 18-month-old cohort. Regression analyses were used to investigate which socio-demographic and/or socio-economic factors related to age-standardised growth. Recruited dyad pairs from three clinics (two public, one private) included 161 infants (boys=71, girls=90), divided into three six-month age groups. Standard nutritional anthropometry was conducted. Statistical associations between age-standardised z-scores with socio-demographic and socio-economic factors (recorded via questionnaires) were assessed, and subsequently used in regression modelling of age-standardised growth. Infants under 6 months grouped between -2 SD and +1 SD for length, weight, and head circumference WHO z-scores; those over 6 months grouped between -1 SD and +2SD. Stunting was more prevalent in infants under six months, and overweight for infants over six months, with a higher prevalence in boys, including wasting. Stunting prevalence in this cohort was under 3%, much lower than the national prevalence reported as 27.5% (<5 years). Conversely, more than 6% were overweight/obese, similar to previous national prevalence (<5 years). Positive significant contributors in regression models were maternal age and education for age-standardised length, weight, and head circumference; gestational age for length and head circumference; exclusive breastfeeding duration for head circumference only; household occupancy and age complementary foods were introduced, for length and weight; explaining some growth trajectory variance within this cohort. Although most of these infants fell within the WHO growth standard norm, the negative age-standardised results for infants under six months may explain overweight/obesity prevalence in those over six months. This research contributes to the knowledge of populational growth differences of healthy full-term infants that may inform the aetiology of adult-onset NCDs.
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    Socio-ecological risk factors, explanatory models and treatment-seeking behaviours associated with Mseleni joint disease: a biocultural mixed methods study
    (2022) Dinkele, Elizabeth Sarah; Gibbon, Victoria E; Ballo, Robea
    Mseleni Joint Disease (MJD) is a crippling osteoarthropathy of unknown aetiology endemic to southern African Bantu-language speakers in a remote region of Northern KwaZulu-Natal, South Africa. Effective management of MJD has been hindered by limited insight into risk factors, explanatory models or treatment-seeking behaviours in those affected. Until MJD is better understood, disability, unemployment and dependence on social assistance grants and family income for subsistence will remain a reality for those affected. A mixed methods study was conducted with the aims of examining risk factors, explanatory models and treatment-seeking behaviours associated with MJD. The distribution, differential diagnosis and treatment of MJD were statistically analysed using medical records (n=723), MJD-patient surveys (n=37) and a meta-analysis. Socio-economic and cultural risk factors were assessed from surveys (n=99) and census publications. Interviews with MJD patients (n=6), nurses (n=7) and doctors (n=9) were qualitatively analysed for themes pertaining to perceptions, experiences and treatment-seeking for MJD. A point prevalence of 9% was estimated. Women were nearly twice as likely to have MJD than men (OR= 1.89; p=0.03) and the likelihood of MJD increased almost three-fold in those older than 50 years (OR= 2.83; p<0.01). Age was a confounder of the association between gender and MJD, as the sample was skewed in the representation of elderly women. MJD was only detected in patients older than 35 years, indicative of a later onset age than previously reported. The prevalence of MJD in settlements along tar and concrete roads, with access to public transport but limited piped water was suggestive of environmental risk factors or differential access to hospital-based care. Explanatory models of MJD were supernatural (witchcraft or ancestral displeasure); natural (nutritional deficiencies, 'genetics' and/or environmental); and/or social (gender-based practices and lifestyle). MJD patients described supernatural and natural aetiologies, and conceptualised disability as an inevitable reality. Consequently, patients reported taking few measures to prevent joint immobility, focussing instead on immediate symptomatic relief. Psychosocial and systemic barriers to treatment were suggestive of a disconnect between traditional African healing and Western biomedicine. This work demonstrates the value of the biocultural approach in identifying spatial, ecological, social and cultural processes that shape population patterns of health and disease.