Clinical and immunological epidemiology of group B streptococcus (GBS)

A thesis submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy Johannesburg 2015Introduction: Group B Streptococcus (GBS) is a leading cause of neonatal sepsis and meningitis. Vaccinating pregnant women against GBS may protect their infants from invasive GBS disease. The licensure of GBS vaccines might be based on immunological parameters should correlates of protection be established. We evaluated the burden of invasive GBS disease, and explored the association between naturally occurring GBS antibody concentrations and invasive GBS disease in South African infants. Methods: Using a case-control study, we compared maternal and infant GBS serotypespecific capsular and surface-protein IgG antibody concentrations. Neurodevelopmental screening was performed at 3 and 6 months-of-age. Furthermore, we compared the effect of maternal HIV-infection on GBS specific antibody concentrations and transplacental antibody transfer. Results: The incidence (per 1,000 live births) of invasive GBS disease within 6 days of life was similar between HIV-exposed (1.13) and HIV-unexposed infants (1.46; p=0.487). However, there was a 4.67-fold (95% CI: 2.24-9.74) greater risk of invasive GBS disease at age 7-90 days in HIV-exposed infants (2.27 vs. 0.49; p<0.001). The overall case fatality ratio among cases was 18.0%, and the adjusted odds of developing neurological sequelae at 6 months age was 13.2-fold (95% CI: 1.4-121) greater in cases (13.2%) than controls (0.4%). Median antibody concentrations (μg/mL) were lower in HIV-infected than HIV-uninfected women for serotypes Ib (p=0.033) and V (p=0.040); and for pilus island (PI)-1 (p=0.016), PI-2a (p=0.015), PI-2b (p=0.015) and fibrinogen-binding protein A (p<0.001). For serotypes Ia and III, cord to maternal ratios were 37.4% (p<0.001) and 32.5% (p=0.027) lower in HIV-infected compared to HIV-uninfected mother-newborn dyads. Using Bayesian modelling, we demonstrated >90% reduction in risk of invasive GBS disease with maternal antibody concentrations ≥6 μg/mL and ≥3 μg/mL for serotype Ia and III, respectively. There was no association between GBS surface-protein antibody concentrations and invasive GBS disease. Conclusion: The high burden of invasive GBS disease in South Africa is partly due to the high prevalence of maternal HIV-infection (29%), which is associated with lower GBS antibody concentrations and transplacental antibody transfer. We identified putative correlates of protection for GBS serotype-specific capsular antibodies to serotypes Ia and III, which could facilitate vaccine licensure

A time-series analysis on the impact of the antiretroviral treatment program on the burden of hospitalization for culture-confirmed Mycobacterium tuberculosis in Sowetan children

A research report submitted to the Faculty of Health Sciences, University of the Witwatersrand, in partial fulfillment for the degree Masters of Medicine in Paediatrics (MMed) Johannesburg 2012Introduction: Highly active antiretroviral treatment (HAART) programs in heavily HIV-TB burdened countries may reduce the risk of TB in children directly by improving the immune system of HIV-infected children; and indirectly by reducing the force of transmission from the adult population. The incidence of childhood TB is a sentinel measure of the control of infectious adult TB cases in the community. Objective: We evaluated the impact that scaling-up of the HAART program in Soweto had on the incidence of hospitalization for culture-confirmed TB in children. Methods: The study was undertaken in Soweto, where the prevalence of HIV was 4-5% in children between 2005 and 2009. The estimated HAART coverage increased from 43% in 2005 to 84% by 2009 in children with HIV/AIDS. Hospitalized cases of culture-confirmed TB in children 3 months to 14 years of age were identified through laboratory and clinical electronic databases. Results: Overall, the incidence (per 100 000) of hospitalization for culture-confirmed TB declined by 58% (95%CI 49.3-65.2) from 2005 (71.4) compared to 2008-9 (30.0); p<0.0001. This included a 67% (95%CI 58.5-74.8) reduction in incidence among HIV-infected children from 2005 (1 601) compared to 2008-9 (517; p<0.0001). v In addition, a 33% reduction was observed in HIV-uninfected children (incidence 19.3 vs 12.9; p=0.016). Fifty-six percent of TB episodes, across all study periods, occurred in HIV-infected children who were mainly (76%) severely immunocompromised. Conclusions: Up-scaling of the HAART program in South Africa has been associated with decline in the incidence of culture-confirmed TB, more so in HIV-infected than HIV-uninfected children. Severely immunocompromised HIV-infected children, however, need to be identified and targeted with HAART and other strategies to further reduce the burden of TB in this group

Ultrastructure for the diagnosis of primary ciliary dyskinesia in South Africa, a resource-limited setting

Introduction: International guidelines recommend a multi-faceted approach for successful diagnoses of primary ciliary dyskinesia (PCD). In the absence of a gold standard test, a combination of genetic testing/microscopic analysis of structure and function/nasal nitric oxide measurement is used. In resourcelimited settings, often none of the above tests are available, and in South Africa, only transmission electron microscopy (TEM) is available in central anatomical pathology departments. The aim of this study was to describe the clinical and ultrastructural findings of suspected PCD cases managed by pediatric pulmonologists at a tertiary-level state funded hospital in Johannesburg. Methods: Nasal brushings were taken from 14 children with chronic respiratory symptoms in keeping with a PCD phenotype. Ultrastructural analysis in accordance with the international consensus guidelines for TEM-PCD diagnostic reporting was undertaken. Results: TEM observations confirmed 43% (6) of the clinically-suspected cases (hallmark ultrastructural defects in the dynein arms of the outer doublets), whilst 57% (8) required another PCD testing modality to support ultrastructural observations. Of these, 25% (2) had neither ultrastructural defects nor did they present with bronchiectasis. Of the remaining cases, 83% (5) had very few ciliated cells (all of which were sparsely ciliated), together with goblet cell hyperplasia. There was the apparent absence of ciliary rootlets in 17% (1) case. Discussion: In resource-limited settings in which TEM is the only available testing modality, confirmatory and probable diagnoses of PCD can be made to facilitate early initiation of treatment of children with chronic respiratory symptoms

Long-term healthcare utilisation, costs and quality of life after invasive group B Streptococcus disease: a cohort study in five low-income and middle-income countries

Introduction There are no published data on the long-term impact of invasive group B Streptococcus disease (iGBS) on economic costs or health-related quality of life (HRQoL) in low-income and middle-income countries. We assessed the impact of iGBS on healthcare utilisation, costs and HRQoL in Argentina, India, Kenya, Mozambique and South Africa. Methods Inpatient and outpatient visits, out-of-pocket (OOP) healthcare payments in the 12 months before study enrolment, and health-state utility of children and caregivers (using the EuroQol 5-Dimensions-3-Level) were collected from iGBS survivors and an unexposed cohort matched on site, age at recruitment and sex. We used logistic or Poisson regression for analysing healthcare utilisation and zero-inflated gamma regression models for family and health system costs. For HRQoL, we used a zero-inflated beta model of disutility pooled data. Results 161 iGBS-exposed and 439 unexposed children and young adults (age 1–20) were included in the analysis. Compared with unexposed participants, iGBS was associated with increased odds of any healthcare utilisation in India (adjusted OR 11.2, 95% CI 2.9 to 43.1) and Mozambique (6.8, 95% CI 2.2 to 21.1) and more frequent healthcare visits (adjusted incidence rate ratio (IRR) for India 1.7 (95% CI 1.4 to 2.2) and for Mozambique 6.0 (95% CI 3.2 to 11.2)). iGBS was also associated with more frequent days in inpatient care in India (adjusted IRR 4.0 (95% CI 2.3 to 6.8) and Kenya 6.4 (95% CI 2.9 to 14.3)). OOP payments were higher in the iGBS cohort in India (adjusted mean: Int$682.22 (95$364.28 to Int$1000.16) vs Int$133.95 (95% CI Int$72.83 to Int$195.06)) and Argentina (Int$244.86 (95$47.38 to Int$442.33) vs Int$52.38 (95% CI Int$−1.39 to Int$106.1)). For all remaining sites, differences were in the same direction but not statistically significant for almost all outcomes. Health-state disutility was higher in iGBS survivors (0.08, 0.04–0.13 vs 0.06, 0.02–0.10). Conclusion The iGBS health and economic burden may persist for years after acute disease. Larger studies are needed for more robust estimates to inform the cost-effectiveness of iGBS prevention

Group B streptococcus infection during pregnancy and infancy: estimates of regional and global burden

Background: Group B streptococcus (GBS) colonisation during pregnancy can lead to invasive GBS disease (iGBS) in infants, including meningitis or sepsis, with a high mortality risk. Other outcomes include stillbirths, maternal infections, and prematurity. There are data gaps, notably regarding neurodevelopmental impairment (NDI), especially after iGBS sepsis, which have limited previous global estimates. In this study, we aimed to address this gap using newly available multicountry datasets. Methods: We collated and meta-analysed summary data, primarily identified in a series of systematic reviews published in 2017 but also from recent studies on NDI and stillbirths, using Bayesian hierarchical models, and estimated the burden for 183 countries in 2020 regarding: maternal GBS colonisation, iGBS cases and deaths in infants younger than 3 months, children surviving iGBS affected by NDI, and maternal iGBS cases. We analysed the proportion of stillbirths with GBS and applied this to the UN-estimated stillbirth risk per country. Excess preterm births associated with maternal GBS colonisation were calculated using meta-analysis and national preterm birth rates. Findings: Data from the seven systematic reviews, published in 2017, that informed the previous burden estimation (a total of 515 data points) were combined with new data (17 data points) from large multicountry studies on neurodevelopmental impairment (two studies) and stillbirths (one study). A posterior median of 19·7 million (95% posterior interval 17·9–21·9) pregnant women were estimated to have rectovaginal colonisation with GBS in 2020. 231800 (114 100–455000) early-onset and 162 200 (70200–394 400) late-onset infant iGBS cases were estimated to have occurred. In an analysis assuming a higher case fatality rate in the absence of a skilled birth attendant, 91 900 (44800–187 800) iGBS infant deaths were estimated; in an analysis without this assumption, 58300 (26 500–125800) infant deaths from iGBS were estimated. 37100 children who recovered from iGBS (14600–96200) were predicted to develop moderate or severe NDI. 40500 (21500–66 200) maternal iGBS cases and 46200 (20 300–111300) GBS stillbirths were predicted in 2020. GBS colonisation was also estimated to be potentially associated with considerable numbers of preterm births. Interpretation: Our analysis provides a comprehensive assessment of the pregnancy-related GBS burden. The Bayesian approach enabled coherent propagation of uncertainty, which is considerable, notably regarding GBS-associated preterm births. Our findings on both the acute and long-term consequences of iGBS have public health implications for understanding the value of investment in maternal GBS immunisation and other preventive strategies

Quantifying long-term health and economic outcomes for survivors of group B Streptococcus invasive disease in infancy: protocol of a multi-country study in Argentina, India, Kenya, Mozambique and South Africa

Sepsis and meningitis due to invasive group B Streptococcus (iGBS) disease during early infancy is a leading cause of child mortality. Recent systematic estimates of the worldwide burden of GBS suggested that there are 319,000 cases of infant iGBS disease each year, and an estimated 147,000 stillbirths and young-infant deaths, with the highest burden occurring in Sub-Saharan Africa. The following priority data gaps were highlighted: (1) long-term outcome data after infant iGBS, including mild disability, to calculate quality-adjusted life years (QALYs) or disability-adjusted life years (DALYs) and (2) economic burden for iGBS survivors and their families. Geographic data gaps were also noted with few studies from low- and middle- income countries (LMIC), where the GBS burden is estimated to be the highest. In this paper we present the protocol for a multi-country matched cohort study designed to estimate the risk of long-term neurodevelopmental impairment (NDI), socioemotional behaviors, and economic outcomes for children who survive invasive GBS disease in Argentina, India, Kenya, Mozambique, and South Africa. Children will be identified from health demographic surveillance systems, hospital records, and among participants of previous epidemiological studies. The children will be aged between 18 months to 17 years. A tablet-based custom-designed application will be used to capture data from direct assessment of the child and interviews with the main caregiver. In addition, a parallel sub-study will prospectively measure the acute costs of hospitalization due to neonatal sepsis or meningitis, irrespective of underlying etiology. In summary, these data are necessary to characterize the consequences of iGBS disease and enable the advancement of effective strategies for survivors to reach their developmental and economic potential. In particular, our study will inform the development of a full public health value proposition on maternal GBS immunization that is being coordinated by the World Health Organization

Factors affecting antenatal care attendance in Soweto, Johannesburg: The three-delay model

Background: Antenatal care remains critical for identifying and managing complications contributing to maternal and infant mortality, yet attendance among women in South Africa persists as a challenge. Aim: This study aimed to understand the challenges faced by women attending antenatal care in Soweto, Johannesburg, using the three-delay model. Setting: This study was conducted in Soweto, Johannesburg. Methods: An exploratory, descriptive and qualitative research design was used, and in-depth interviews were conducted with 10 pregnant women and four women who had recently given birth. Results: Findings indicate delays in seeking care due to factors such as pregnancy unawareness, waiting for visible signs, and fear of human immunodeficiency virus (HIV) testing. Challenges such as transportation difficulties, distance to clinics, and facility conditions further impeded the initiation of antenatal care. Late initiation often occurred to avoid long waits, inadequate facilities, language barriers and nurse mistreatment. Conclusion: From this study, we learn that challenges such as unawareness of pregnancy, cultural notions of keeping pregnancy a secret, fear of HIV testing, long waiting lines, high cost of transportation fees, clinic demarcation, shortage of essential medicines, broken toilets and verbal abuse from nurses have delayed women from initiating antenatal care early in Soweto, Johannesburg. Contribution: Challenges of women with antenatal care attendance in South Africa must be addressed by implementing community-based health education interventions, institutionalising HIV psycho-social support services and improving quality of antenatal care services in public health facilities

Bronchiectasis in African children : challenges and barriers to care

Bronchiectasis (BE) is a chronic condition aecting the bronchial tree. It is characterized by the dilatation of large and medium-sized airways, secondary to damage of the underlying bronchial wall structural elements and accompanied by the clinical picture of recurrent or persistent cough. Despite an increased awareness of childhood BE, there is still a paucity of data on the epidemiology, pathophysiological phenotypes, diagnosis, management, and outcomes in Africa where the prevalence is mostly unmeasured, and likely to be higher than high-income countries. Diagnostic pathways and management principles have largely been extrapolated from approaches in adults and children in high-income countries or from data in children with cystic fibrosis. Here we provide an overview of pediatric BE in Africa, highlighting risk factors, diagnostic and management challenges, need for a global approach to addressing key research gaps, and recommendations for practitioners working in Africa.http://www.frontiersin.org/Pediatricsdm2022Paediatrics and Child Healt

Quantifying the Acute Care Costs of Neonatal Bacterial Sepsis and Meningitis in Mozambique and South Africa.

BACKGROUND: Sepsis and meningitis are among the leading causes of neonatal deaths in sub-Saharan Africa (SSA). Neonatal sepsis caused ~400 000 deaths globally in 2015, half occurring in Africa. Despite this, there are few published data on the acute costs of neonatal sepsis or meningitis, with none in SSA. METHODS: We enrolled neonates admitted to 2 hospitals in South Africa and Mozambique between 16 April 2020 and 1 April 2021. In South Africa all cases were microbiologically confirmed, but in Mozambique both clinically suspected and microbiologically confirmed cases were included. Data were collected on healthcare resource use and length of stay, along with information on household expenditure and caregiving. We used unit costs of healthcare resources in local currencies to estimate healthcare provider costs per patient and costs per household. Results were converted to 2019 international dollars (I$). RESULTS: We enrolled 11 neonates in Mozambique and 18 neonates in South Africa. Mean length of stay was 10 days (median, 9 [interquartile range {IQR}, 4-14) and 16 days (median, 15 [IQR, 13-18]), respectively. In Mozambique we estimated mean household costs of I$49.62 (median, 10.19 [IQR, 5.10-95.12]) and hospitalization costs of I$307.58 (median, 275.12 [IQR, 149.43-386.12]). In South Africa these costs were I$52.31 (median, 30.82 [IQR, 19.25-73.08]) and I$684.06 (median, 653.62 [IQR, 543.33-827.53]), respectively. CONCLUSIONS: We found substantial costs associated with acute neonatal bacterial (all-cause) sepsis and meningitis in SSA. Our estimates will inform economic evaluations of interventions to prevent neonatal invasive bacterial infections

South African Children: A Matched Cohort Study of Neurodevelopmental Impairment in Survivors of Invasive Group B Streptococcus Disease Aged 5 to 8 Years.

BACKGROUND: Invasive group B Streptococcus (iGBS) sepsis and meningitis are important causes of child mortality, but studies on neurodevelopmental impairment (NDI) after iGBS are limited. Using Griffiths Mental Development Scales-Extended Revised (GMDS-ER), we described NDI in iGBS survivors and non-iGBS children from South Africa, as part of a 5-country study. METHODS: We identified children aged 5-8 years with a history of iGBS and children with no history of iGBS between October 2019 and January 2021. Children were matched on sex, and birth data (month, year) (matched cohort study). Moderate or Severe NDI was the primary outcome as a composite of GMDS-ER motor, GMDS-ER cognition, hearing, and vision. Secondary outcomes included mild NDI, any emotional-behavioral problems, and GMDS-ER developmental quotients (DQ) calculated by dividing the age equivalent GMDS-ER score by the chronological age. RESULTS: In total, 160 children (iGBS survivors, 43; non-iGBS, 117) were assessed. Among iGBS survivors 13 (30.2%) had meningitis, and 30 (69.8%) had sepsis. Six (13.9%) iGBS survivors, and 5 (4.3%) non-iGBS children had moderate or severe NDI. Children who survived iGBS were 5.56 (95% confidence interval [CI]: 1.07-28.93; P = .041) times more likely to have moderate or severe NDI at 5-8 years than non-iGBS children. Compared to the non-iGBS children, iGBS meningitis survivors had a significantly lower global median DQ (P < .05), as well as a lower median DQ for the language GMDS-ER subscale and performance GMDS-ER subscale (P < .05). CONCLUSIONS: Children surviving iGBS, particularly meningitis, are more likely to have NDI at 5-8 years compared to non-iGBS children. Further research is required to improve detection and care for at-risk newborns