A5084558976- HIV/AIDS Research and Interventions
- HIV Research and Treatment
- HIV, Drug Use, Sexual Risk
- Adolescent Sexual and Reproductive Health
- HIV/AIDS drug development and treatment
- HIV/AIDS Impact and Responses
- Tuberculosis Research and Epidemiology
- SARS-CoV-2 and COVID-19 Research
- COVID-19 Clinical Research Studies
- Vaccine Coverage and Hesitancy
- Bayesian Methods and Mixture Models
- SARS-CoV-2 detection and testing
- COVID-19 epidemiological studies
- HIV-related health complications and treatments
- Statistical Methods and Bayesian Inference
- Data-Driven Disease Surveillance
- Pneumonia and Respiratory Infections
- Sex work and related issues
- Advanced Biosensing Techniques and Applications
- Pneumocystis jirovecii pneumonia detection and treatment
- Biosensors and Analytical Detection
- Census and Population Estimation
- Mathematical and Theoretical Epidemiology and Ecology Models
- Blood groups and transfusion
- Cervical Cancer and HPV Research
Stellenbosch University
2015-2024
National Research Foundation
2012-2024
Star Information Systems (Norway)
2022
Vitalant
2021
University of the Free State
2021
University of California, San Francisco
2021
ORCID
2021
University of Cape Town
2021
University of the Witwatersrand
2008-2011
HES-SO Genève
2009
Objective: Cross-sectional HIV incidence surveillance, using assays that distinguish 'recent' from 'nonrecent' infections, has been hampered by inadequate performance and characterization of assays. In this study, the Consortium for Evaluation Performance Incidence Assays presents results first independent evaluation five (BED, Limiting Antigen Avidity, Less-sensitive Vitros, Vitros Avidity BioRad Avidity). Design: A large repository diverse specimens HIV-positive patients was established,...
Background Mean duration of recent infection (MDRI) and misclassification long-term HIV-1 infections, as proportion false (PFR), are critical parameters for laboratory-based assays estimating incidence. Recent review the data by us others indicated that MDRI LAg-Avidity EIA estimated previously required recalibration. We present here results recalibration efforts using >250 seroconversion panels multiple statistical methods to ensure accuracy consensus. Methods A total 2737 longitudinal...
Assays for classifying HIV infections as 'recent' or 'nonrecent' incidence surveillance fail to simultaneously achieve large mean durations of infection (MDRIs) and low 'false-recent' rates (FRRs), particularly in virally suppressed persons. The potential optimizing recent testing algorithms (RITAs), by introducing viral load criteria tuning thresholds used dichotomize quantitative measures, is explored.The Consortium the Evaluation Performance Incidence characterized over 2000 possible...
Population-level estimates of prevalence anti-SARS-CoV-2 antibody positivity (seroprevalence) is a crucial epidemiological indicator for tracking the Covid-19 epidemic. Such data are in short supply, both internationally and South Africa. The African blood services (the National Blood Service, SANBS Western Cape WCBS) coordinating nationally representative survey donors, which it hoped can become cost-effective surveillance method with validity community-level seroprevalence estimation....
Background: Estimating disease incidence from cross-sectional surveys, using biomarkers for "recent" infection, has attracted much interest. Despite widespread applications to HIV, there is currently no consensus on the correct handling of biomarker results classifying persons as "recently" infected long after infections occurred. Methods: We derive a general expression weighted average recent that—unlike previous estimators—requires particular assumption about infection dynamics or...
Public health responses to HIV epidemics have long relied on epidemiological modelling analyses help prospectively project and retrospectively estimate the impact, cost-effectiveness, affordability, investment returns of interventions, plan design evaluations. But translating model output into policy decisions implementation ground is challenged by differences in background expectations modellers decision-makers. As part PLoS Medicine Collection "Investigating Impact Treatment New...
Background The BED IgG-Capture Enzyme Immunoassay (cBED assay), a test of recent HIV infection, has been used to estimate incidence in cross-sectional surveys. However, there concern that the assay overestimates an unknown extent because it falsely classifies some individuals with non-recent infections as recently infected. We data from longitudinal surveillance rural South Africa measure fraction people infection who are classified HIV-infected by cBED (the long-term false-positive ratio...
Efficient HIV prevention requires accurate identification of individuals with risky sexual behaviour. However, self-reported data from behaviour surveys are prone to social desirability bias (SDB). Audio Computer-Assisted Self-Interviewing (ACASI) has been suggested as an alternative face-to-face interviewing (FTFI), because it may promote interview privacy and reduce SDB. little is known about the suitability accuracy ACASI in urban communities high prevalence South Africa. To test this, we...
In 1998 we estimated that 34/million infectious window period donations were entering the blood supply at South African National Blood Service. Selective use of based on donor race-ethnicity reduced this risk to 26/million but was deemed unethical. Consequently, in 2005 Service eliminated race-ethnicity-based collection policies and implemented individual-donation nucleic acid testing (ID-NAT). We describe change base demographics, human immunodeficiency virus (HIV) detection rates,...
In line with previous instalments of analysis from this ongoing study to monitor 'Covid Seroprevalence' among blood donors in South Africa, we report on an 3395 samples obtained mid-March 2022 all provinces Africa - a timepoint just after the fourth (primarily omicron) wave infections. As our analyses, see no evidence age and sex dependence prevalence, but significant variation by race. Differences between have largely disappeared, as prevalence appears saturated. contrast estimates study,...
Objective: To estimate the proportion who test as recent infections by BED capture enzyme immunoassay (BED) among patients about to commence, and those receiving, antiretroviral therapy. Design: Cryopreserved plasma samples from HIV on national treatment (ART) rollout program at Tygerberg Hospital clinic, South Africa, were tested using assay. Participants: Five hundred five qualifying for ART included in this study. Method: All each patient BED. Basic demographic data, HIV-1 viral load, CD4...
Potent antiretroviral therapy (ART) reduces mortality and morbidity in people living with HIV by reducing viral load allowing their immune systems to recover. The reduction soon after starting ART has led the hypothesis that early widespread could prevent onward transmission therefore eliminate epidemic long term. While several authors have argued it is feasible use treatment as prevention (TasP), provided started sufficiently early, others reasonably drawn attention many operational...
BackgroundWHO's 2013 revisions to its Consolidated Guidelines on antiretroviral drugs recommend routine viral load monitoring, rather than clinical or immunological as the preferred monitoring approach basis of evidence. However, HIV programmes in resource-limited settings require guidance most cost-effective use resources view other competing priorities such expansion therapy coverage. We assessed cost-effectiveness alternative patient strategies.MethodsWe evaluated a range strategies,...
Human immunodeficiency virus (HIV) antibodies are generated and maintained by ongoing systemic expression of HIV antigen. We investigated whether antibody responses as measured high-throughput quantitative qualitative assays could be used to indirectly measure persistent replication in individuals receiving antiretroviral therapy (ART).HIV were over time the presence or absence suppressive ART compared reservoir size antiviral restriction factors.Among untreated individuals, including both...
South Africa has over 6,000,000 HIV infected individuals and the province of KwaZulu-Natal (KZN) is most severely affected. As public health initiatives to better control epidemic are implemented, timely, detailed robust surveillance data needed monitor, evaluate inform programmatic interventions policies time. We describe rationale design Incidence Provincial Surveillance System (HIPSS) monitor prevalence incidence. The household-based survey will include a sample men women from two...
Dengue virus (DENV) infections elicit antibody responses to the non-structural protein 1 (NS1) that are associated with protection against disease. However, isotypes and subclasses involved, their kinetics have not been extensively studied. We characterized DENV NS1 by enzyme-linked immunosorbent assay (ELISA) in a longitudinal cohort of 266 confirmed dengue cases Recife, Northeast Brazil. Samples were collected during febrile phase up over 3 years after onset symptoms. The antibodies...
Tests for recent infection (TRIs), such as the BED assay, provide a convenient way to estimate HIV incidence rates from cross-sectional survey data. Controversy has arisen over how imperfect performance of TRI should be characterised and taken into account. Recent theoretical work is providing unified framework within which with variety TRI- epidemic-specific assumptions in order using TRIs, but suggests that larger sample sizes will required than previously thought. This paper reviews...
Abstract Background It is frequently of epidemiological and/or clinical interest to estimate the date HIV infection or time-since-infection individuals. Yet, for over 15 years, only widely-referenced dating algorithm that utilises diagnostic testing data has been ‘Fiebig staging’ system. This defines a number stages early through various standard combinations contemporaneous discordant results using tests different sensitivity. To develop new, more nuanced algorithm, we generalised Fiebig...