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Wang Z, Zhang Z, Zhang C, Jin X, Wu J, Su B, Shen Y, Ruan Y, Xing H, Lou J. Trace the History of HIV and Predict Its Future through Genetic Sequences. Trop Med Infect Dis 2022; 7:tropicalmed7080190. [PMID: 36006282 PMCID: PMC9416588 DOI: 10.3390/tropicalmed7080190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Revised: 08/10/2022] [Accepted: 08/11/2022] [Indexed: 11/16/2022] Open
Abstract
Traditional methods of quantifying epidemic spread are based on surveillance data. The most widely used surveillance data are normally incidence data from case reports and hospital records, which are normally susceptible to human error, and sometimes, they even can be seriously error-prone and incomplete when collected during a destructive epidemic. In this manuscript, we introduce a new method to study the spread of infectious disease. We gave an example of how to use this method to predict the virus spreading using the HIV gene sequences data of China. First, we applied Bayesian inference to gene sequences of two main subtypes of the HIV virus to infer the effective reproduction number (GRe(t)) to trace the history of HIV transmission. Second, a dynamic model was established to forecast the spread of HIV medication resistance in the future and also obtain its effective reproduction number (MRe(t)). Through fitting the two effective reproduction numbers obtained from the two separate ways above, some crucial parameters for the dynamic model were obtained. Simply raising the treatment rate has no impact on lowering the infection rate, according to the dynamics model research, but would instead increase the rate of medication resistance. The negative relationship between the prevalence of HIV and the survivorship of infected individuals following treatment may be to blame for this. Reducing the MSM population’s number of sexual partners is a more efficient strategy to reduce transmission per the sensitivity analysis.
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Affiliation(s)
- Zhen Wang
- Department of Mathematics, Shanghai University, Shanghai 200444, China
| | - Zhiyuan Zhang
- Department of Statistics, Columbia University, New York, NY 10027, USA
| | - Chen Zhang
- School of Nursing, University of Rochester, Rochester, NY 14627, USA
| | - Xin Jin
- Department of Mathematics, Shanghai University, Shanghai 200444, China
| | - Jianjun Wu
- Anhui Provincial Center for Disease Control and Prevention, Hefei 230601, China
| | - Bin Su
- Anhui Provincial Center for Disease Control and Prevention, Hefei 230601, China
| | - Yuelan Shen
- Anhui Provincial Center for Disease Control and Prevention, Hefei 230601, China
| | - Yuhua Ruan
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, and National Center for AIDS/STD Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, China
| | - Hui Xing
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, and National Center for AIDS/STD Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, China
| | - Jie Lou
- Department of Mathematics, Shanghai University, Shanghai 200444, China
- Correspondence:
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Risher KA, Cori A, Reniers G, Marston M, Calvert C, Crampin A, Dadirai T, Dube A, Gregson S, Herbst K, Lutalo T, Moorhouse L, Mtenga B, Nabukalu D, Newton R, Price AJ, Tlhajoane M, Todd J, Tomlin K, Urassa M, Vandormael A, Fraser C, Slaymaker E, Eaton JW. Age patterns of HIV incidence in eastern and southern Africa: a modelling analysis of observational population-based cohort studies. Lancet HIV 2021; 8:e429-e439. [PMID: 34197773 PMCID: PMC8258368 DOI: 10.1016/s2352-3018(21)00069-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 03/10/2021] [Accepted: 03/23/2021] [Indexed: 01/12/2023]
Abstract
BACKGROUND As the HIV epidemic in sub-Saharan Africa matures, evidence about the age distribution of new HIV infections and how this distribution has changed over the epidemic is needed to guide HIV prevention. We aimed to assess trends in age-specific HIV incidence in six population-based cohort studies in eastern and southern Africa, reporting changes in mean age at infection, age distribution of new infections, and birth cohort cumulative incidence. METHODS We used a Bayesian model to reconstruct age-specific HIV incidence from repeated observations of individuals' HIV serostatus and survival collected among population HIV cohorts in rural Malawi, South Africa, Tanzania, Uganda, and Zimbabwe, in a collaborative analysis of the ALPHA network. We modelled HIV incidence rates by age, time, and sex using smoothing splines functions. We estimated incidence trends separately by sex and study. We used estimated incidence and prevalence results for 2000-17, standardised to study population distribution, to estimate mean age at infection and proportion of new infections by age. We also estimated cumulative incidence (lifetime risk of infection) by birth cohort. FINDINGS Age-specific incidence declined at all ages, although the timing and pattern of decline varied by study. The mean age at infection was higher in men (cohort mean 27·8-34·6 years) than in women (24·8-29·6 years). Between 2000 and 2017, the mean age at infection per cohort increased slightly: 0·5 to 2·8 years among men and -0·2 to 2·5 years among women. Across studies, between 38% and 63% (cohort medians) of the infections in women were among those aged 15-24 years and between 30% and 63% of infections in men were in those aged 20-29 years. Lifetime risk of HIV declined for successive birth cohorts. INTERPRETATION HIV incidence declined in all age groups and shifted slightly to older ages. Disproportionate new HIV infections occur among women aged 15-24 years and men aged 20-29 years, supporting focused prevention in these groups. However, 40-60% of infections were outside these ages, emphasising the importance of providing appropriate HIV prevention to adults of all ages. FUNDING Bill & Melinda Gates Foundation.
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Affiliation(s)
- Kathryn A Risher
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, UK; Department of Population Health, London School of Hygiene & Tropical Medicine, London, UK.
| | - Anne Cori
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, UK
| | - Georges Reniers
- Department of Population Health, London School of Hygiene & Tropical Medicine, London, UK; Medical Research Council/Wits University Rural Public Health and Health Transitions Research Unit (Agincourt), School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Milly Marston
- Department of Population Health, London School of Hygiene & Tropical Medicine, London, UK
| | - Clara Calvert
- Department of Population Health, London School of Hygiene & Tropical Medicine, London, UK
| | - Amelia Crampin
- Department of Population Health, London School of Hygiene & Tropical Medicine, London, UK; Institute of Health and Wellbeing, University of Glasgow, Glasgow, UK
| | - Tawanda Dadirai
- The Manicaland Centre for Public Health Research, Harare, Zimbabwe
| | - Albert Dube
- Malawi Epidemiology and Intervention Research Unit, Karonga, Malawi
| | - Simon Gregson
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, UK; Biomedical Research and Training Institute, Harare, Zimbabwe
| | - Kobus Herbst
- Africa Health Research Institute, KwaZulu-Natal, Durban, South Africa; Department of Science and Innovation-Medical Research Council South African Population Research Infrastructure Network, Durban, South Africa
| | - Tom Lutalo
- Rakai Health Sciences Program, Kalisizo, Uganda
| | - Louisa Moorhouse
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, UK
| | - Baltazar Mtenga
- National Institute for Medical Research, Kisesa HDSS, Mwanza, Tanzania
| | | | - Robert Newton
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe, Uganda; Department of Health Sciences, University of York, York, UK
| | - Alison J Price
- Department of Population Health, London School of Hygiene & Tropical Medicine, London, UK
| | - Malebogo Tlhajoane
- Department of Population Health, London School of Hygiene & Tropical Medicine, London, UK
| | - Jim Todd
- Department of Population Health, London School of Hygiene & Tropical Medicine, London, UK
| | - Keith Tomlin
- Department of Population Health, London School of Hygiene & Tropical Medicine, London, UK
| | - Mark Urassa
- National Institute for Medical Research, Kisesa HDSS, Mwanza, Tanzania
| | - Alain Vandormael
- Africa Health Research Institute, KwaZulu-Natal, Durban, South Africa; KwaZulu-Natal Research Innovation and Sequencing Platform, UKZN, Durban, South Africa; Heidelberg Institute of Global Health, Faculty of Medicine, University of Heidelberg, Heidelberg, Germany
| | - Christophe Fraser
- Oxford Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Emma Slaymaker
- Department of Population Health, London School of Hygiene & Tropical Medicine, London, UK
| | - Jeffrey W Eaton
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, UK; Department of Population Health, London School of Hygiene & Tropical Medicine, London, UK
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Mathematical Model Describing HIV Infection with Time-Delayed CD4 T-Cell Activation. Processes (Basel) 2020. [DOI: 10.3390/pr8070782] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
A mathematical model composed of two non-linear differential equations that describe the population dynamics of CD4 T-cells in the human immune system, as well as viral HIV viral load, is proposed. The invariance region is determined, classical equilibrium stability analysis is performed by using the basic reproduction number, and numerical simulations are carried out to illustrate stability results. Thereafter, the model is modified with a delay term, describing the time required for CD4 T-cell immunological activation. This generates a two-dimensional integro-differential system, which is transformed into a system with three ordinary differential equations. For the new model, equilibriums are determined, their local stability is examined, and results are studied by way of numerical simulation.
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Black A, Sitas F, Chibrawara T, Gill Z, Kubanje M, Williams B. HIV-attributable causes of death in the medical ward at the Chris Hani Baragwanath Hospital, South Africa. PLoS One 2019; 14:e0215591. [PMID: 31059528 PMCID: PMC6502348 DOI: 10.1371/journal.pone.0215591] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 04/04/2019] [Indexed: 01/28/2023] Open
Abstract
INTRODUCTION Data on the association between HIV infection and deaths from underlying medical conditions are needed to understand and assess the impact of HIV on mortality. We present data on mortality in the Chris Hani Baragwanath Hospital (CHBH) South Africa and analyse the relationship between each cause of death and HIV. METHODS From 2006 to 2009 data were collected on 15,725 deaths including age, sex, day of admittance and of death, HIV status, ART initiation and CD4+ cell counts. Causes of death associated with HIV were cases, causes of death not associated with HIV were controls. We calculate the odds-ratios (ORs) for being HIV-positive and for each AIDS related condition the disease-attributable fraction (DAF) and the population-attributable fraction (PAF) due to HIV for cases relative to controls. RESULTS Among those that died, the prevalence of HIV was 61% and of acquired immune deficiency syndrome (AIDS) related conditions was 69%. The HIV-attributable fraction was 36% in the whole sample and 60% in those that were HIV-positive. Cryptococcosis, Kaposi's sarcoma and Pneumocystis jirovecii, TB, gastroenteritis and anaemia were highly predictive of HIV with odds ratios for being HIV-positive ranging from 8 to 124, while genito-urinary conditions, meningitis, other respiratory conditions and sepsis, lymphoma and conditions of skin and bone were significantly associated with HIV with odds ratios for being HIV-positive ranging from 3 to 8. Most of the deaths attributable to HIV were among those dying of TB or of other respiratory conditions. CONCLUSIONS The high prevalence of HIV among those that died, peaking at 70% in those aged 30 years but still 7% in those aged 80 years, demonstrates the impact of the HIV epidemic on adult mortality and on hospital services and the extent to which early anti-retroviral treatment would have reduced the burden of both. These data make it possible to better assess mortality and morbidity due to HIV in this still high prevalence setting and, in particular, to identify those causes of death that are most strongly associated with HIV.
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Affiliation(s)
- Andrew Black
- Department of Internal Medicine, University of the Witwatersrand, Johannesburg, South Africa
| | - Freddy Sitas
- Centre for Primary Health Care and Equity, School of Public Health and Community Medicine, University of New South Wales, Kensington, Australia.,Menzies Centre for Health Policy, Sydney School of Public Health, University of Sydney, Camperdown, Australia
| | - Trust Chibrawara
- South African Centre for Epidemiological Modelling and Analysis, Stellenbosch University, Stellenbosch, South Africa
| | - Zoe Gill
- South African Centre for Epidemiological Modelling and Analysis, Stellenbosch University, Stellenbosch, South Africa
| | - Mmamapudi Kubanje
- South African Centre for Epidemiological Modelling and Analysis, Stellenbosch University, Stellenbosch, South Africa
| | - Brian Williams
- South African Centre for Epidemiological Modelling and Analysis, Stellenbosch University, Stellenbosch, South Africa
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Geffen N, Welte A. Modelling the human immunodeficiency virus (HIV) epidemic: A review of the substance and role of models in South Africa. South Afr J HIV Med 2018; 19:756. [PMID: 29568647 PMCID: PMC5843995 DOI: 10.4102/sajhivmed.v19i1.756] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 08/07/2017] [Indexed: 01/01/2023] Open
Abstract
We review key mathematical models of the South African human immunodeficiency virus (HIV) epidemic from the early 1990s onwards. In our descriptions, we sometimes differentiate between the concepts of a model world and its mathematical or computational implementation. The model world is the conceptual realm in which we explicitly declare the rules – usually some simplification of ‘real world’ processes as we understand them. Computing details of informative scenarios in these model worlds is a task requiring specialist knowledge, but all other aspects of the modelling process, from describing the model world to identifying the scenarios and interpreting model outputs, should be understandable to anyone with an interest in the epidemic.
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Affiliation(s)
- Nathan Geffen
- Department of Computer Science, Centre for Social Science Research, University of Cape Town, South Africa
| | - Alex Welte
- South African Centre for Epidemiological Modelling and Analysis (SACEMA), University of Stellenbosch, South Africa
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Abstract
PURPOSE OF REVIEW We describe the role of activism in improving access to quality HIV treatment. RECENT FINDINGS In many countries, AIDS activists have campaigned for improved access to HIV treatment and prevention interventions. Studying medicine, epidemiology and law, and developing expertise in these fields, has been crucial to the success of these campaigns. Also important has been the building of alliances by activists with clinicians, nurses, scientists, and public health policy experts, persuading them of the importance of these campaigns. This article describes examples of campaigns in several middle and low-income countries, showing how activists, by becoming familiar with HIV science, have helped make antiretrovirals available to millions of people across the world. HIV activists have also been drawn into, and driven, broader struggles for health social justice, such as campaigns for new tuberculosis and hepatitis C. SUMMARY Scientists and activists need to continue to work together to improve access to treatment. But to be effective, a critical mass of activists must develop expertise in HIV science and the law.
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Blaizot S, Huerga H, Riche B, Ellman T, Shroufi A, Etard JF, Ecochard R. Combined interventions to reduce HIV incidence in KwaZulu-Natal: a modelling study. BMC Infect Dis 2017; 17:522. [PMID: 28747167 PMCID: PMC5530541 DOI: 10.1186/s12879-017-2612-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 07/18/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Combined prevention interventions, including early antiretroviral therapy initiation, may substantially reduce HIV incidence in hyperendemic settings. Our aim was to assess the potential short-term impact of combined interventions on HIV spreading in the adult population of Mbongolwane and Eshowe (KwaZulu-Natal, South Africa) using sex- and age-specific scenarios, and age-targeted interventions. METHODS A mathematical model was used with data on adults (15-59 years) from the Mbongolwane and Eshowe HIV Impact in Population Survey to compare the effects of various interventions on the HIV incidence rate. These interventions included increase in antiretroviral therapy (ART) coverage with extended eligibility criteria, increase in voluntary medical male circumcision (VMMC), and implementation of pre-exposure prophylaxis (PrEP) among women. RESULTS With no additional interventions to the ones in place at the time of the survey (ART at CD4 < 350 and VMMC), incidence will decrease by 24% compared to the baseline rate. The implementation of "ART at CD4<500" or "ART for all" would reduce further the incidence rate by additional 8% and 15% respectively by 4 years and 20% and 34% by 10 years. Impacts would be higher with age-targeted scenarios than without. CONCLUSIONS In Mbongolwane and Eshowe, implementation of the new South African guidelines, recommending ART initiation regardless of CD4 count, would accelerate incidence reduction. In this setting, combining these guidelines, VMMC, and PrEP among young women could be an effective strategy in reducing the incidence to low levels.
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Affiliation(s)
- Stéphanie Blaizot
- Service de Biostatistique, Hospices Civils de Lyon, F-69003 Lyon, France
- Université de Lyon, F-69000 Lyon, France
- Université Lyon 1, F-69100 Villeurbanne, France
- CNRS UMR 5558, Equipe Biostatistique-Santé, Laboratoire de Biométrie et Biologie Evolutive, F-69100 Villeurbanne, France
| | | | - Benjamin Riche
- Service de Biostatistique, Hospices Civils de Lyon, F-69003 Lyon, France
- Université de Lyon, F-69000 Lyon, France
- Université Lyon 1, F-69100 Villeurbanne, France
- CNRS UMR 5558, Equipe Biostatistique-Santé, Laboratoire de Biométrie et Biologie Evolutive, F-69100 Villeurbanne, France
| | - Tom Ellman
- Médecins Sans Frontières, Cape Town, South Africa
| | - Amir Shroufi
- Médecins Sans Frontières, Cape Town, South Africa
| | - Jean-François Etard
- Epicentre, F-75011 Paris, France
- IRD UMI 233, INSERM U1175, Université de Montpellier, Unité TransVIHMI, F-34000 Montpellier, France
| | - René Ecochard
- Service de Biostatistique, Hospices Civils de Lyon, F-69003 Lyon, France
- Université de Lyon, F-69000 Lyon, France
- Université Lyon 1, F-69100 Villeurbanne, France
- CNRS UMR 5558, Equipe Biostatistique-Santé, Laboratoire de Biométrie et Biologie Evolutive, F-69100 Villeurbanne, France
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Expanded antiretroviral treatment, sexual networks, and condom use: Treatment as prevention unlikely to succeed without partner reduction among men who have sex with men in China. PLoS One 2017; 12:e0171295. [PMID: 28406992 PMCID: PMC5390964 DOI: 10.1371/journal.pone.0171295] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 01/19/2017] [Indexed: 12/26/2022] Open
Abstract
Background To project the impact of partner reduction on preventing new HIV infections among men who have sex with men (MSM) under varying conditions of enhanced HIV testing and treatment (T&T) and condom use in Beijing, China. Methods and findings A complex network model was fitted to predict the number of new HIV infections averted from 2014 to 2023 under four scenarios of sexual behavior risk reduction (S)—S1: Male sexual partners decrease (reduced by a random value m from 1–50) while condom use increases (risk constant p is a random value between 0.2 and 1]); S2: Both sexual partners and condom use decrease (m 1, 50; p 1, 1.8); S3: Sexual partners reduce (m 1, 10) while condom use increases or decreases (p 0.2, 1.8); S4: Only MSM with ≥100 male sexual partners reduce their partners (m 1, 50) while condom use increases (p 0.2, 1). HIV prevalence will reach 23.2% by 2023 among Beijing MSM if T&T remains at the 2013 level. The three most influential factors are: T&T coverage; partner reduction (m); and the background risk (p). Under scenarios 1–4 of sexual behavioral changes with enhanced T&T interventions, the cumulative HIV new infections prevented over the 10 years will be 46.8% for S1 (interquartile range [IQR] 32.4%, 60.1%); 29.7% for S2 (IQR 18.0%, 41.4%), 23.2% for S3 (IQR 12.2%, 37.0%) and 11.6% for S4 (IQR 4.0%, 26.6%), respectively. The reproduction number R0 could drop below 1 if there were a substantial reduction of male sexual partners and/or expanded condom use. Conclusion Partner reduction is a vital factor within HIV combination interventions to reduce HIV incidence among Beijing MSM, with substantial additional benefits derived from condom use. T&T without substantial partner reduction and increased condom use is less promising unless its implementation were extremely (and improbably) efficient.
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Reniers G, Blom S, Calvert C, Martin-Onraet A, Herbst AJ, Eaton JW, Bor J, Slaymaker E, Li ZR, Clark SJ, Bärnighausen T, Zaba B, Hosegood V. Trends in the burden of HIV mortality after roll-out of antiretroviral therapy in KwaZulu-Natal, South Africa: an observational community cohort study. Lancet HIV 2017; 4:e113-e121. [PMID: 27956187 PMCID: PMC5405557 DOI: 10.1016/s2352-3018(16)30225-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 10/13/2016] [Accepted: 10/24/2016] [Indexed: 01/10/2023]
Abstract
BACKGROUND Antiretroviral therapy (ART) substantially decreases morbidity and mortality in people living with HIV. In this study, we describe population-level trends in the adult life expectancy and trends in the residual burden of HIV mortality after the roll-out of a public sector ART programme in KwaZulu-Natal, South Africa, one of the populations with the most severe HIV epidemics in the world. METHODS Data come from the Africa Centre Demographic Information System (ACDIS), an observational community cohort study in the uMkhanyakude district in northern KwaZulu-Natal, South Africa. We used non-parametric survival analysis methods to estimate gains in the population-wide life expectancy at age 15 years since the introduction of ART, and the shortfall of the population-wide adult life expectancy compared with that of the HIV-negative population (ie, the life expectancy deficit). Life expectancy gains and deficits were further disaggregated by age and cause of death with demographic decomposition methods. FINDINGS Covering the calendar years 2001 through to 2014, we obtained information on 93 903 adults who jointly contribute 535 42 8 person-years of observation to the analyses and 9992 deaths. Since the roll-out of ART in 2004, adult life expectancy increased by 15·2 years for men (95% CI 12·4-17·8) and 17·2 years for women (14·5-20·2). Reductions in pulmonary tuberculosis and HIV-related mortality account for 79·7% of the total life expectancy gains in men (8·4 adult life-years), and 90·7% in women (12·8 adult life-years). For men, 9·5% is the result of a decline in external injuries. By 2014, the life expectancy deficit had decreased to 1·2 years for men (-2·9 to 5·8) and to 5·3 years for women (2·6-7·8). In 2011-14, pulmonary tuberculosis and HIV were responsible for 84·9% of the life expectancy deficit in men and 80·8% in women. INTERPRETATION The burden of HIV on adult mortality in this population is rapidly shrinking, but remains large for women, despite their better engagement with HIV-care services. Gains in adult life-years lived as well as the present life expectancy deficit are almost exclusively due to differences in mortality attributed to HIV and pulmonary tuberculosis. FUNDING Wellcome Trust, the Bill & Melinda Gates Foundation, and the National Institutes of Health.
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Affiliation(s)
- Georges Reniers
- Department of Population Health, London School of Hygiene & Tropical Medicine, London, UK; School of Public Health, University of the Witwatersrand, Johannesburg, South Africa.
| | - Sylvia Blom
- Department of Population Health, London School of Hygiene & Tropical Medicine, London, UK
| | - Clara Calvert
- Department of Population Health, London School of Hygiene & Tropical Medicine, London, UK
| | | | | | - Jeffrey W Eaton
- Department of Infectious Disease Epidemiology, Imperial College London, London, UK
| | - Jacob Bor
- Department of Global Health, Boston University, Boston, MA, USA
| | - Emma Slaymaker
- Department of Population Health, London School of Hygiene & Tropical Medicine, London, UK
| | - Zehang R Li
- Department of Statistics, University of Washington, Seattle, WA, USA
| | - Samuel J Clark
- School of Public Health, University of the Witwatersrand, Johannesburg, South Africa; Department of Sociology, The Ohio State University, Columbus, OH, USA
| | - Till Bärnighausen
- Africa Health Research Institute, Durban, South Africa; Institute of Public Health, University of Heidelberg, Heidelberg, Germany; Harvard TH Chan School of Public Health, Harvard University, Boston, MA, USA
| | - Basia Zaba
- Department of Population Health, London School of Hygiene & Tropical Medicine, London, UK
| | - Victoria Hosegood
- Africa Health Research Institute, Durban, South Africa; Social Statistics and Demography, University of Southampton, Southampton, UK
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Blaizot S, Maman D, Riche B, Mukui I, Kirubi B, Ecochard R, Etard JF. Potential impact of multiple interventions on HIV incidence in a hyperendemic region in Western Kenya: a modelling study. BMC Infect Dis 2016; 16:189. [PMID: 27129591 PMCID: PMC4851795 DOI: 10.1186/s12879-016-1520-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 04/18/2016] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Multiple prevention interventions, including early antiretroviral therapy initiation, may reduce HIV incidence in hyperendemic settings. Our aim was to predict the short-term impact of various single and combined interventions on HIV spreading in the adult population of Ndhiwa subcounty (Nyanza Province, Kenya). METHODS A mathematical model was used with data on adults (15-59 years) from the Ndhiwa HIV Impact in Population Survey to compare the impacts on HIV prevalence, HIV incidence rate, and population viral load suppression of various interventions. These interventions included: improving the cascade of care (use of three guidelines), increasing voluntary medical male circumcision (VMMC), and implementing pre-exposure prophylaxis (PrEP) use among HIV-uninfected women. RESULTS After four years, improving separately the cascade of care under the WHO 2013 guidelines and under the treat-all strategy would reduce the overall HIV incidence rate by 46 and 58 %, respectively, vs. the baseline rate, and by 35 and 49 %, respectively, vs. the implementation of the current Kenyan guidelines. With conservative and optimistic scenarios, VMMC and PrEP would reduce the HIV incidence rate by 15-25 % and 22-28 % vs. the baseline, respectively. Combining the WHO 2013 guidelines with VMMC would reduce the HIV incidence rate by 35-56 % and combining the treat-all strategy with VMMC would reduce it by 49-65 %. Combining the WHO 2013 guidelines, VMMC, and PrEP would reduce the HIV incidence rate by 46-67 %. CONCLUSIONS The impacts of the WHO 2013 guidelines and the treat-all strategy were relatively close; their implementation is desirable to reduce HIV spread. Combining several strategies is promising in adult populations of hyperendemic areas but requires regular, reliable, and costly monitoring.
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Affiliation(s)
- Stéphanie Blaizot
- Service de Biostatistique, Hospices Civils de Lyon, F-69003, Lyon, France. .,Université de Lyon, F-69000, Lyon, France. .,Université Lyon 1, F-69100, Villeurbanne, France. .,CNRS UMR 5558, Equipe Biostatistique-Santé, Laboratoire de Biométrie et Biologie Evolutive, F-69100, Villeurbanne, France.
| | | | - Benjamin Riche
- Service de Biostatistique, Hospices Civils de Lyon, F-69003, Lyon, France.,Université de Lyon, F-69000, Lyon, France.,Université Lyon 1, F-69100, Villeurbanne, France.,CNRS UMR 5558, Equipe Biostatistique-Santé, Laboratoire de Biométrie et Biologie Evolutive, F-69100, Villeurbanne, France
| | - Irene Mukui
- National AIDS and STDs Control Program, Nairobi, Kenya
| | | | - René Ecochard
- Service de Biostatistique, Hospices Civils de Lyon, F-69003, Lyon, France.,Université de Lyon, F-69000, Lyon, France.,Université Lyon 1, F-69100, Villeurbanne, France.,CNRS UMR 5558, Equipe Biostatistique-Santé, Laboratoire de Biométrie et Biologie Evolutive, F-69100, Villeurbanne, France
| | - Jean-François Etard
- Epicentre, F-75011, Paris, France.,UMI 233 TransVIHMI, Institut de Recherche pour le Développement, Université Montpellier 1, F-34000, Montpellier, France
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Abstract
OBJECTIVES Empirical estimates of the number of HIV/AIDS deaths are important for planning, budgeting, and calibrating models. However, there is an extensive misattribution of HIV/AIDS as an underlying cause-of-death. This study estimates the true numbers of AIDS deaths from South African vital statistics between 1997 and 2010. METHODS Individual-level cause-of-death data were grouped according to a local burden of disease list and source causes (i.e. causes under which AIDS deaths are misclassified) that recorded a rapid increase. After adjusting for completeness of registration, the mortality rate of the source causes, by age and sex, was regressed on the lagged HIV prevalence to estimate the rate of increase correlated with HIV. Background trends in the source-cause mortality rates were estimated from the trend experienced among 75-84 year olds. RESULTS Of 214 causes considered, 19 were identified as potential sources for cause misattribution. High proportions of deaths from tuberculosis, lower respiratory infections (mostly pneumonia), diarrhoeal diseases, and ill-defined natural causes were estimated to be HIV-related, with only 7% of the estimated AIDS deaths being recorded as HIV. Estimated HIV/AIDS deaths increased rapidly, then reversed after 2006, totalling 2.8 million deaths over the whole period. The number was lower than model estimates from Joint United Nations Programme on HIV/AIDS (UNAIDS) and the Global Burden of Disease Study. CONCLUSION Empirically based estimates confirm the considerable loss of life from HIV/AIDS and should be used for calibrating models of the AIDS epidemic which generally appear too low for infants but too high for other ages. Doctors are urged to specify HIV on death notifications to provide reliable cause-of-death statistics.
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Lou J, Blevins M, Ruan Y, Vermund SH, Tang S, Webb GF, Shepherd BE, He X, Lu H, Shao Y, Qian HZ. Modeling the impact on HIV incidence of combination prevention strategies among men who have sex with men in Beijing, China. PLoS One 2014; 9:e90985. [PMID: 24626165 PMCID: PMC3953201 DOI: 10.1371/journal.pone.0090985] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 02/05/2014] [Indexed: 11/25/2022] Open
Abstract
OBJECTIVE To project the HIV/AIDS epidemics among men who have sex with men (MSM) under different combinations of HIV testing and linkage to care (TLC) interventions including antiretroviral therapy (ART) in Beijing, China. DESIGN Mathematical modeling. METHODS Using a mathematical model to fit prevalence estimates from 2000-2010, we projected trends in HIV prevalence and incidence during 2011-2020 under five scenarios: (S1) current intervention levels by averaging 2000-2010 coverage; (S2) increased ART coverage with current TLC; (S3) increased TLC/ART coverage; (S4) increased condom use; and (S5) increased TLC/ART plus increased condom use. RESULTS The basic reproduction number based upon the current level of interventions is significantly higher than 1 (R0 = 2.09; 95% confidence interval (CI), 1.83-2.35), suggesting that the HIV epidemic will continue to increase to 2020. Compared to the 2010 prevalence of 7.8%, the projected HIV prevalence in 2020 for the five prevention scenarios will be: (S1) Current coverage: 21.4% (95% CI, 9.9-31.7%); (S2) Increased ART: 19.9% (95% CI, 9.9-28.4%); (S3) Increased TLC/ART: 14.5% (95% CI, 7.0-23.8%); (S4) Increased condom use: 13.0% (95% CI, 9.8-28.4%); and (S5) Increased TLC/ART and condom use: 8.7% (95% CI, 5.4-11.5%). HIV epidemic will continue to rise (R0 > 1) for S1-S4 even with hyperbolic coverage in the sensitivity analysis, and is expected to decline (R0 = 0.93) for S5. CONCLUSION Our transmission model suggests that Beijing MSM will have a rapidly rising HIV epidemic. Even enhanced levels of TLC/ART will not interrupt epidemic expansion, despite optimistic assumptions for coverage. Promoting condom use is a crucial component of combination interventions.
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Affiliation(s)
- Jie Lou
- Department of Mathematics, Shanghai University, Shanghai, China
| | - Meridith Blevins
- Vanderbilt Institute for Global Health, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Biostatistics, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Yuhua Ruan
- State Key Laboratory for Infectious Disease Prevention and Control, National Center for AIDS/STD Control and Prevention, Chinese Center for Disease Control and Prevention, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Beijing, China
| | - Sten H. Vermund
- Vanderbilt Institute for Global Health, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Pediatrics, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Sanyi Tang
- College of Mathematics and Information Science, Shaanxi Normal University, Xi'an, Shaanxi Province, China
| | - Glenn F. Webb
- Department of Mathematics, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Bryan E. Shepherd
- Vanderbilt Institute for Global Health, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Biostatistics, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Xiong He
- Institute for AIDS/STD Prevention & Control, Beijing Municipal Center for Disease Control and Prevention, Beijing, China
| | - Hongyan Lu
- Institute for AIDS/STD Prevention & Control, Beijing Municipal Center for Disease Control and Prevention, Beijing, China
| | - Yiming Shao
- State Key Laboratory for Infectious Disease Prevention and Control, National Center for AIDS/STD Control and Prevention, Chinese Center for Disease Control and Prevention, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Beijing, China
| | - Han-Zhu Qian
- Vanderbilt Institute for Global Health, Vanderbilt University, Nashville, Tennessee, United States of America
- Division of Epidemiology, Department of Medicine, Vanderbilt University, Nashville, Tennessee, United States of America
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Mesa Mazo MJ, ZAPATA HERNÁNDARÍOTORO, Prieto Medellín DA. Modelo de simulación para la transmisión del VIH y estrategias de control basadas en diagnóstico. Rev Salud Publica (Bogota) 2014. [DOI: 10.15446/rsap.v16n1.37421] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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Johnson LF, Mossong J, Dorrington RE, Schomaker M, Hoffmann CJ, Keiser O, Fox MP, Wood R, Prozesky H, Giddy J, Garone DB, Cornell M, Egger M, Boulle A. Life expectancies of South African adults starting antiretroviral treatment: collaborative analysis of cohort studies. PLoS Med 2013; 10:e1001418. [PMID: 23585736 PMCID: PMC3621664 DOI: 10.1371/journal.pmed.1001418] [Citation(s) in RCA: 302] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Accepted: 02/28/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Few estimates exist of the life expectancy of HIV-positive adults receiving antiretroviral treatment (ART) in low- and middle-income countries. We aimed to estimate the life expectancy of patients starting ART in South Africa and compare it with that of HIV-negative adults. METHODS AND FINDINGS Data were collected from six South African ART cohorts. Analysis was restricted to 37,740 HIV-positive adults starting ART for the first time. Estimates of mortality were obtained by linking patient records to the national population register. Relative survival models were used to estimate the excess mortality attributable to HIV by age, for different baseline CD4 categories and different durations. Non-HIV mortality was estimated using a South African demographic model. The average life expectancy of men starting ART varied between 27.6 y (95% CI: 25.2-30.2) at age 20 y and 10.1 y (95% CI: 9.3-10.8) at age 60 y, while estimates for women at the same ages were substantially higher, at 36.8 y (95% CI: 34.0-39.7) and 14.4 y (95% CI: 13.3-15.3), respectively. The life expectancy of a 20-y-old woman was 43.1 y (95% CI: 40.1-46.0) if her baseline CD4 count was ≥ 200 cells/µl, compared to 29.5 y (95% CI: 26.2-33.0) if her baseline CD4 count was <50 cells/µl. Life expectancies of patients with baseline CD4 counts ≥ 200 cells/µl were between 70% and 86% of those in HIV-negative adults of the same age and sex, and life expectancies were increased by 15%-20% in patients who had survived 2 y after starting ART. However, the analysis was limited by a lack of mortality data at longer durations. CONCLUSIONS South African HIV-positive adults can have a near-normal life expectancy, provided that they start ART before their CD4 count drops below 200 cells/µl. These findings demonstrate that the near-normal life expectancies of HIV-positive individuals receiving ART in high-income countries can apply to low- and middle-income countries as well. Please see later in the article for the Editors' Summary.
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Affiliation(s)
- Leigh F Johnson
- Centre for Infectious Disease Epidemiology and Research, University of Cape Town, Cape Town, South Africa.
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15
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Johnson LF, Stinson K, Newell ML, Bland RM, Moultrie H, Davies MA, Rehle TM, Dorrington RE, Sherman GG. The contribution of maternal HIV seroconversion during late pregnancy and breastfeeding to mother-to-child transmission of HIV. J Acquir Immune Defic Syndr 2012; 59:417-25. [PMID: 22193774 PMCID: PMC3378499 DOI: 10.1097/qai.0b013e3182432f27] [Citation(s) in RCA: 112] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
BACKGROUND The prevention of mother-to-child transmission (PMTCT) of HIV has been focused mainly on women who are HIV positive at their first antenatal visit, but there is uncertainty regarding the contribution to overall transmission from mothers who seroconvert after their first antenatal visit and before weaning. METHOD A mathematical model was developed to simulate changes in mother-to-child transmission of HIV over time, in South Africa. The model allows for changes in infant feeding practices as infants age, temporal changes in the provision of antiretroviral prophylaxis and counseling on infant feeding, as well as temporal changes in maternal HIV prevalence and incidence. RESULTS The proportion of mother-to-child transmission (MTCT) from mothers who seroconverted after their first antenatal visit was 26% [95% confidence interval (CI): 22% to 30%] in 2008, or 15,000 of 57,000 infections. It is estimated that by 2014, total MTCT will reduce to 39,000 per annum, and transmission from mothers seroconverting after their first antenatal visit will reduce to 13,000 per annum, accounting for 34% (95% CI: 29% to 39%) of MTCT. If maternal HIV incidence during late pregnancy and breastfeeding were reduced by 50% after 2010, and HIV screening were repeated in late pregnancy and at 6-week immunization visits after 2010, the average annual number of MTCT cases over the 2010-2015 period would reduce by 28% (95% CI: 25% to 31%), from 39,000 to 28,000 per annum. CONCLUSION Maternal seroconversion during late pregnancy and breastfeeding contributes significantly to the pediatric HIV burden and needs greater attention in the planning of prevention of MTCT programs.
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Affiliation(s)
- Leigh F Johnson
- Centre for Infectious Disease Epidemiology and Research, School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa.
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16
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Johnson LF, Hallett TB, Rehle TM, Dorrington RE. The effect of changes in condom usage and antiretroviral treatment coverage on human immunodeficiency virus incidence in South Africa: a model-based analysis. J R Soc Interface 2012; 9:1544-54. [PMID: 22258551 DOI: 10.1098/rsif.2011.0826] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
This study aims to assess trends in human immunodeficiency virus (HIV) incidence in South Africa, and to assess the extent to which prevention and treatment programmes have reduced HIV incidence. Two models of the South African HIV epidemic, the STI (sexually transmitted infection)-HIV Interaction model and the ASSA2003 AIDS and Demographic model, were adapted. Both models were fitted to age-specific HIV prevalence data from antenatal clinic surveys and household surveys, using a Bayesian approach. Both models suggest that HIV incidence in 15-49 year olds declined significantly between the start of 2000 and the start of 2008: by 27 per cent (95% CI: 21-32%) in the STI-HIV model and by 31 per cent (95% CI: 23-39%) in the ASSA2003 model, when expressed as a percentage of incidence rates in 2000. By 2008, the percentage reduction in incidence owing to increased condom use was 37 per cent (95% CI: 34-41%) in the STI-HIV model and 23 per cent (95% CI: 14-34%) in the ASSA2003 model. Both models also estimated a small reduction in incidence owing to antiretroviral treatment by 2008. Increased condom use therefore appears to be the most significant factor explaining the recent South African HIV incidence decline.
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Affiliation(s)
- Leigh F Johnson
- Centre for Infectious Disease Epidemiology and Research, University of Cape Town, Cape Town, South Africa.
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Nyabadza F, Mukandavire Z. Modelling HIV/AIDS in the presence of an HIV testing and screening campaign. J Theor Biol 2011; 280:167-79. [DOI: 10.1016/j.jtbi.2011.04.021] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Revised: 04/19/2011] [Accepted: 04/20/2011] [Indexed: 11/29/2022]
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Middelkoop K, Bekker LG, Liang H, Aquino LDH, Sebastian E, Myer L, Wood R. Force of tuberculosis infection among adolescents in a high HIV and TB prevalence community: a cross-sectional observation study. BMC Infect Dis 2011; 11:156. [PMID: 21631918 PMCID: PMC3130671 DOI: 10.1186/1471-2334-11-156] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Accepted: 06/01/2011] [Indexed: 11/10/2022] Open
Abstract
Background Understanding of the transmission dynamics of tuberculosis (TB) in high TB and HIV prevalent settings is required in order to develop effective intervention strategies for TB control. However, there are little data assessing incidence of TB infection in adolescents in these settings. Methods We performed a tuberculin skin test (TST) and HIV survey among secondary school learners in a high HIV and TB prevalence community. TST responses to purified protein derivative RT23 were read after 3 days. HIV-infection was assessed using Orasure® collection device and ELISA testing. The results of the HIV-uninfected participants were combined with those from previous surveys among primary school learners in the same community, and force of TB infection was calculated by age. Results The age of 820 secondary school participants ranged from 13 to 22 years. 159 participants had participated in the primary school surveys. At a 10 mm cut-off, prevalence of TB infection among HIV-uninfected and first time participants, was 54% (n = 334/620). HIV prevalence was 5% (n = 40/816). HIV infection was not significantly associated with TST positivity (p = 0.07). In the combined survey dataset, TB prevalence was 45% (n = 645/1451), and was associated with increasing age and male gender. Force of infection increased with age, from 3% to 7.3% in adolescents ≥20 years of age. Conclusions We show a high force of infection among adolescents, positively associated with increasing age. We postulate this is due to increased social contact with infectious TB cases. Control of the TB epidemic in this setting will require reducing the force of infection.
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Affiliation(s)
- Keren Middelkoop
- Desmond Tutu HIV Centre, Institute of Infectious Diseases and Molecular Medicine, University of Cape Town, Cape Town, South Africa.
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Middelkoop K, Bekker LG, Myer L, Johnson LF, Kloos M, Morrow C, Wood R. Antiretroviral therapy and TB notification rates in a high HIV prevalence South African community. J Acquir Immune Defic Syndr 2011; 56:263-9. [PMID: 21317585 PMCID: PMC3801097 DOI: 10.1097/qai.0b013e31820413b3] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Antiretroviral therapy (ART) has been proposed as an intervention for reducing tuberculosis (TB) burdens in areas with high HIV prevalence. However, little data is available on the impact of ART on population-level TB. METHODS Trends in adult TB case fatality and notifications were assessed before and during increasing ART coverage in a well-defined periurban community, from 1997 to 2008. Mean changes in TB rates were measured using linear autoregression models. ART coverage increased from 1% in 2003 to 5%, 13%, and 21% of HIV-infected population in 2004, 2005, and 2008, respectively. RESULTS From 1997 to end of 2004 TB notification rates increased by an average of 187 cases/100,000/year (P < 0.001), reaching a peak of 2536/100,000 in 2005. From 2005 to 2008, TB notification rates declined by approximately 202 cases/100,000/year (P < 0.001). TB rates were initially stable in HIV-uninfected individuals, but declined moderately from 2005. TB rates declined in HIV-infected adults from 6513/100,000 in 2005 to 4741/100,000 in 2008. The predominant decline in TB notifications occurred among HIV-infected patients receiving ART (1156 cases/100,000/year) and was less marked in those not receiving ART (416 cases/100,000/year). Similarly, TB case fatality was constant for HIV-uninfected individuals, but declined in HIV-infected individuals from 23% in 2002 to 8% in 2008 (P = 0.01). CONCLUSIONS In this community heavily affected by both HIV and TB epidemics, rapid and high ART coverage was associated with significant reductions in TB notifications and TB-associated case fatality.
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Affiliation(s)
- Keren Middelkoop
- Desmond Tutu HIV Centre, Institute of Infectious Diseases and Molecular Medicine, University of Cape Town, Cape Town, South Africa.
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Kim AA, McDougal JS, Hargrove J, Rehle T, Pillay-Van Wyk V, Puren A, Ekra A, Borget-Alloue MY, Adje-Toure C, Abdullahi AS, Odawo L, Marum L, Parekh BS. Evaluating the BED capture enzyme immunoassay to estimate HIV incidence among adults in three countries in sub-Saharan Africa. AIDS Res Hum Retroviruses 2010; 26:1051-61. [PMID: 20849299 DOI: 10.1089/aid.2009.0218] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Serological assays for estimating HIV-1 incidence are prone to misclassification, limiting the accuracy of the incidence estimate. Adjustment factors have been developed and recommended for estimating assay-based HIV-1 incidence in cross-sectional settings. We evaluated the performance of the recommended adjustment factors for estimating incidence in national HIV surveys in three countries in sub-Saharan Africa. The BED-capture enzyme immunoassay was applied to stored blood specimens from (1) pregnant women aged 15-49 years attending antenatal clinics in Côte d'Ivoire (1998-2004), (2) adults aged 15-49 years participating in a demographic health survey in Kenya (2003), and (3) adults aged 15-49 years participating in a national household serosurvey in South Africa (2005). Assay-derived incidence estimates were corrected for misclassification using recommended adjustment factors and, where possible, were compared to mathematically modeled incidence in the same populations. Trends in HIV prevalence were compared to trends in assay-derived incidence to assess plausibility in the assay-derived trends. Unadjusted incidence was 3.8% [95% confidence interval (CI) 3.3-4.5] in Côte d'Ivoire, 3.5% (2.7-4.3) in Kenya, and 4.4% (CI 2.3-6.5]) in South Africa. Adjusted incidence was 2.9% (CI 2.1-3.7) in Côte d'Ivoire, 2.6% (CI 2.0-3.2) in Kenya, and 2.4% (CI 1.7-3.1) in South Africa. After adjustment, peak incidence shifted from older to younger age groups in Côte d'Ivoire and South Africa. Modeled HIV incidence was 1.0% (CI 1.02-1.08) in Kenya and 2.0% (CI 1.7-2.4) in South Africa. After applying the recommended adjustments factors, adjusted assay-derived estimates remained implausibly high in two of three populations evaluated. For more accurate measures of assay-derived population incidence, adjustment factors must be locally derived and validated. Until improved assays are available, caution should be applied in the use and interpretation of data from incidence assays.
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Affiliation(s)
- Andrea A. Kim
- Global AIDS Program, Centers for Disease Control and Prevention (CDC), Atlanta, Georgia
| | | | - John Hargrove
- DST/NRF Centre of Excellence in Epidemiological Modeling and Analysis, SACEMA, Stellenbosch, South Africa
| | - Thomas Rehle
- Human Sciences Research Council, Cape Town, South Africa
| | - Victoria Pillay-Van Wyk
- Human Sciences Research Council, Cape Town, South Africa
- Medical Research Council, Cape Town, South Africa
| | - Adrian Puren
- National Institute for Communicable Diseases, Johannesburg, South Africa
| | - Alexandre Ekra
- Global AIDS Program Côte d'Ivoire, U.S. Centers for Disease Control and Prevention, Abidjan, Côte d'Ivoire
| | | | - Christiane Adje-Toure
- Global AIDS Program Côte d'Ivoire, U.S. Centers for Disease Control and Prevention, Abidjan, Côte d'Ivoire
| | | | - Linus Odawo
- Global AIDS Program Kenya, US Centers for Disease Control and Prevention, Nairobi, Kenya
| | - Lawrence Marum
- Global AIDS Program Kenya, US Centers for Disease Control and Prevention, Nairobi, Kenya
| | - Bharat S. Parekh
- Global AIDS Program, Centers for Disease Control and Prevention (CDC), Atlanta, Georgia
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Bacaër N, Pretorius C, Auvert B. An age-structured model for the potential impact of generalized access to antiretrovirals on the South African HIV epidemic. Bull Math Biol 2010; 72:2180-98. [PMID: 20349152 DOI: 10.1007/s11538-010-9535-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2009] [Accepted: 03/09/2010] [Indexed: 11/28/2022]
Abstract
A simple mathematical model (Granich et al., Lancet 373:48-57, 2009) suggested recently that annual HIV testing of the population, with all detected HIV(+) individuals immediately treated with antiretrovirals, could lead to the long-term decline of HIV in South Africa and could save millions of lives in the next few years. However, the model suggested that the long-term decline of HIV could not be achieved with less frequent HIV testing. Many observers argued that an annual testing rate was very difficult in practice. Small scale trials are nevertheless in preparation. In this paper, we use a more realistic age-structured model, which suggests that the recent high levels of reported condom use could already lead to a long-term decline of HIV in South Africa. The model therefore suggests that trials with for example 20% of the population tested each year would also be interesting. They would have similar (though smaller) advantages in terms of reduction of mortality and incidence, would be much easier to generalize to larger populations, and would not lead to long term persistence of HIV. Our model simulations also suggest that the age distribution of incidence has changed considerably over the past 20 years in South Africa. This raises some concern about an assumption presently used in EPP/Spectrum, the software used by UNAIDS for its estimates.
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Affiliation(s)
- Nicolas Bacaër
- IRD (Institut de Recherche pour le Développement), 32 avenue Henri Varagnat, 93143 Bondy, France
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Sexual behaviour patterns in South Africa and their association with the spread of HIV: insights from a mathematical model. DEMOGRAPHIC RESEARCH 2009. [DOI: 10.4054/demres.2009.21.11] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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Bell C, Gersbach H. The macroeconomics of targeting: the case of an enduring epidemic. JOURNAL OF HEALTH ECONOMICS 2009; 28:54-72. [PMID: 18977545 DOI: 10.1016/j.jhealeco.2008.07.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2006] [Revised: 05/17/2008] [Accepted: 07/17/2008] [Indexed: 05/27/2023]
Abstract
What is the right balance among policy interventions in order to ensure economic growth over the long run when an epidemic causes heavy mortality among young adults? We argue that, in general, policies to combat the disease and promote education must be concentrated, in certain ways, at first on some subgroups of society. This concentration involves what we term the macroeconomics of targeting. The central comparison is then between programs under which supported families enjoy the benefits of spending on health and education simultaneously (DT), and those under which the benefits in these two domains are sequenced (ST). When levels of human capital are uniformly low at the outbreak, DT is superior to ST if the mortality rate exceeds some threshold value. Outside aid makes DT more attractive; but DT restricts support to fewer families initially and so increases inequality. A summary account of the empirical evidence is followed by an application of the framework to South Africa.
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Affiliation(s)
- Clive Bell
- Südasien-Institut, University of Heidelberg, INF 330, 69120 Heidelberg, Germany.
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Abstract
As global efforts proceed to scale up the delivery of antiretroviral therapy (ART) to HIV-infected persons in most urgent need, it is essential to understand the potential impact of treatment expansion on the transmission of new HIV infections. In this study, we use a series of simple mathematical models to explore the direction and magnitude of treatment effects on the sexual transmission of HIV. By defining the circumstances under which ART can reduce the number of new infections transmitted by treated patients, we provide critical benchmarks to aid in prioritizing efforts to maximize the population health impact of treatment and in evaluating the performance of different treatment programmes. We find that, based on the best currently available evidence of possible treatment effects on patient infectiousness, survival and behavior, the potential remains for either positive or negative changes in overall transmission. In relation to the total number of expected secondary infections caused by each infected person, however, these net treatment effects are relatively modest, particularly if treatment is initiated at advanced stages of the disease. This finding implies that treatment alone should not be expected to alter the population-level incidence of new infections dramatically, in the absence of changes in other factors including possible behavioral responses among uninfected persons and among infected persons who are not yet treatment candidates.
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Johnson LF, Bekker LG, Dorrington RE. HIV/AIDS vaccination in adolescents would be efficient and practical when vaccine supplies are limited. Vaccine 2007; 25:7502-9. [PMID: 17904701 DOI: 10.1016/j.vaccine.2007.08.047] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2007] [Revised: 08/20/2007] [Accepted: 08/26/2007] [Indexed: 11/27/2022]
Abstract
The first HIV/AIDS vaccines are likely to be expensive and limited in supply, and developing countries with generalized HIV/AIDS epidemics will need to distribute the limited vaccine stock in a manner that is both efficient and practical. This analysis compares seven strategies for distributing an HIV/AIDS vaccine in different South African sub-populations, using a mathematical model. If vaccination is not coupled with HIV screening, vaccination of 16-year olds in school is likely to be the most efficient strategy for averting HIV infections in the short term. If coupled with screening, vaccination of sex workers and patients seeking STD treatment would be more efficient, but these gains in efficiency would have to be weighed against the practical challenges associated with vaccinating 'high risk' groups and conducting screening.
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Affiliation(s)
- Leigh F Johnson
- Centre for Actuarial Research, University of Cape Town, Private bag, Rondebosch 7701, South Africa.
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Gregson S, Nyamukapa C, Lopman B, Mushati P, Garnett GP, Chandiwana SK, Anderson RM. Critique of early models of the demographic impact of HIV/AIDS in sub-Saharan Africa based on contemporary empirical data from Zimbabwe. Proc Natl Acad Sci U S A 2007; 104:14586-91. [PMID: 17761795 PMCID: PMC1961581 DOI: 10.1073/pnas.0611540104] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Early mathematical models varied in their predictions of the impact of HIV/AIDS on population growth from minimal impact to reductions in growth, in pessimistic scenarios, from positive to negative values over a period of 25 years. Models predicting negative rates of natural increase forecast little effect on the dependency ratio. Twenty years later, HIV prevalence in small towns, estates, and rural villages in eastern Zimbabwe, has peaked within the intermediate range predicted by the early models, but the demographic impact has been more acute than was predicted. Despite concurrent declines in fertility, fueled in part by HIV infections (total fertility is now 8% lower than expected without an epidemic), and a doubling of the crude death rate because of HIV/AIDS, the rate of natural population increase between 1998 and 2005 remained positive in each socioeconomic stratum. In the worst-affected areas (towns with HIV prevalence of 33%), HIV/AIDS reduced growth by two-thirds from 2.9% to 1.0%. The dependency ratio fell from 1.21 at the onset of the HIV epidemic to 0.78, the impact of HIV-associated adult mortality being outweighed by fertility decline. With the benefit of hindsight, the more pessimistic early models overestimated the demographic impact of HIV epidemics by overextrapolating initial HIV growth rates or not allowing for heterogeneity in key parameters such as transmissibility and sexual risk behavior. Data collected since the late 1980s show that there was a mismatch between the observed growth in the HIV epidemic and assumptions made about viral transmission.
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Affiliation(s)
- Simon Gregson
- Department of Infectious Disease Epidemiology, Imperial College London, London W2 1PG, United Kingdom.
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