Browsing by Author "McNaughton, Anna L."

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Bimodal distribution and set point HBV DNA viral loads in chronic infection : retrospective analysis of cohorts from the UK and South Africa
    (Wellcome Open Research, 2020-10-14) Downs, Louise O.; Vawda, Sabeehah; Bester, Phillip Armand; Lythgoe, Katrina A.; Wang, Tingyan; McNaughton, Anna L.; Smith, David A.; Maponga, Tongai; Freeman, Oliver; Várnai, Kinga A.; Davies, Jim; Woods, Kerrie; Fraser, Christophe; Barnes, Eleanor; Goedhals, Dominique; Matthews, Philippa C.
    ENGLISH ABSTRACT: Hepatitis B virus (HBV) viral load (VL) is used as a biomarker to assess risk of disease progression, and to determine eligibility for treatment. While there is a well recognised association between VL and the expression of the viral e-antigen protein, the distributions of VL at a population level are not well described. We here present cross-sectional, observational HBV VL data from two large population cohorts in the UK and in South Africa, demonstrating a consistent bimodal distribution. The right skewed distribution and low median viral loads are different from the left-skew and higher viraemia in seen in HIV and hepatitis C virus (HCV) cohorts in the same settings. Using longitudinal data, we present evidence for a stable 'set-point' VL in peripheral blood during chronic HBV infection. These results are important to underpin improved understanding of HBV biology, to inform approaches to viral sequencing, and to plan public health interventions.
  • Thumbnail Image
    Item
    Hepatitis B virus infection as a neglected tropical disease
    (Public Library of Science, 2017-10-05) O'Hara, Geraldine A.; McNaughton, Anna L.; Maponga, Tongai; Jooste, Pieter; Ocama, Ponsiano; Chileng, Roma; Mokaya, Jolynne; Liyayi, Mitchell I.; Wachira, Tabitha; Gikungi, David M.; Burbridge, Lela; O'Donnel, Denise; Akiror, Connie S.; Sloan, Derek; Torimiro, Judith; Yindom, Louis Marie; Walton, Robert; Andersson, Monique; Marsh, Kevin; Newton, Robert; Matthews, Philippa C.
    ENGLISH ABSTRACT: The Global Hepatitis Health Sector Strategy is aiming for “elimination of viral hepatitis as a public health threat” by 2030 [1], while enhanced elimination efforts for hepatitis are also promoted under the broader remit of global Sustainable Development Goals (SDGs) [2]. This is an enormous challenge for hepatitis B virus (HBV) given the estimated global burden of 260 million chronic carriers, of whom the majority are unaware of their infection [3] (Fig 1). We here present HBV within the framework for neglected tropical diseases (NTDs) [4] in order to highlight the ways in which HBV meets NTD criteria and to discuss the ways in which the NTD management paradigm could be used to strengthen a unified global approach to HBV elimination [5]. The major burden of morbidity and mortality from HBV is now borne by tropical and subtropical countries [6]. Many African populations epitomize specific vulnerability to HBV [7], so we here focus particular attention on Africa, both through focus on the existing published literature and through presentation of a unique data set of opinion and experience (see S1 Supporting Information). However, the themes we represent are transferable to other low- and middle-income settings and are relevant on the global stage.
  • Thumbnail Image
    Item
    Hepatitis B virus seroepidemiology data for Africa : modelling intervention strategies based on a systematic review and meta-analysis
    (Public Library of Science, 2021-04-21) McNaughton, Anna L.; Lourenco, Jose; Bester, Phillip Armand; Mokaya, Jolynne; Lumley, Sheila F.; Obolski, Uri; Forde, Donall; Maponga, Tongai G.; Katumba, Kenneth R.; Goedhals, Dominique; Gupta, Sunetra; Seeley, Janet; Newton, Robert; Ocama, Ponsiano; Matthews, Philippa C.
    Background: International Sustainable Development Goals (SDGs) for elimination of hepatitis B virus (HBV) infection set ambitious targets for 2030. In African populations, infant immunisation has been fundamental to reducing incident infections in children, but overall population prevalence of chronic hepatitis B (CHB) infection remains high. In high-prevalence populations, adult catch-up vaccination has sometimes been deployed, but an alternative Test and Treat (T&T) approach could be used as an intervention to interrupt transmission. Universal T&T has not been previously evaluated as a population intervention for HBV infection, despite high-profile data supporting its success with human immunodeficiency virus (HIV). Methods and findings: We set out to investigate the relationship between prevalence of HBV infection and exposure in Africa, undertaking a systematic literature review in November 2019. We identified published seroepidemiology data representing the period 1995–2019 from PubMed and Web of Science, including studies of adults that reported prevalence of both hepatitis B surface antigen (HBsAg; prevalence of HBV infection) and antibody to hepatitis B core antigen (anti-HBc; prevalence of HBV exposure). We identified 96 studies representing 39 African countries, with a median cohort size of 370 participants and a median participant age of 34 years. Using weighted linear regression analysis, we found a strong relationship between the prevalence of infection (HBsAg) and exposure (anti-HBc) (R2 = 0.45, p < 0.001). Region-specific differences were present, with estimated CHB prevalence in Northern Africa typically 30% to 40% lower (p = 0.007) than in Southern Africa for statistically similar exposure rates, demonstrating the need for intervention strategies to be tailored to individual settings. We applied a previously published mathematical model to investigate the effect of interventions in a high-prevalence setting. The most marked and sustained impact was projected with a T&T strategy, with a predicted reduction of 33% prevalence by 20 years (95% CI 30%–37%) and 62% at 50 years (95% CI 57%–68%), followed by routine neonatal vaccination and prevention of mother to child transmission (PMTCT; at 100% coverage). In contrast, the impact of catch-up vaccination in adults had a negligible and transient effect on population prevalence. The study is constrained by gaps in the published data, such that we could not model the impact of antiviral therapy based on stratification by specific clinical criteria and our model framework does not include explicit age-specific or risk-group assumptions regarding force of transmission. Conclusions: The unique data set collected in this study highlights how regional epidemiology data for HBV can provide insights into patterns of transmission, and it provides an evidence base for future quantitative research into the most effective local interventions. In combination with robust neonatal immunisation programmes, ongoing PMTCT efforts, and the vaccination of high-risk groups, diagnosing and treating HBV infection is likely to be of most impact in driving advances towards elimination targets at a population level.