229 results found
Van de Velde N, Brisson M, Boily M-C, 2010, Understanding differences in predictions of HPV vaccine effectiveness: A comparative model-based analysis, VACCINE, Vol: 28, Pages: 5473-5484, ISSN: 0264-410X
Phillips AE, Lowndes CM, Boily MC, et al., 2010, Men who have sex with men and women inBangalore, South India, and potential impact on the HIV epidemic, Sex Transm Infect, Vol: 86, Pages: 187-192
Mishra S, Naik B, Venugopal B, et al., 2010, Syphilis screening among female sex workers in Bangalore, India: comparison of point-of-care testing and traditional serological approaches, SEXUALLY TRANSMITTED INFECTIONS, Vol: 86, Pages: 193-198, ISSN: 1368-4973
Baggaley RF, White RG, Boily M-C, 2010, HIV transmission risk through anal intercourse: systematic review, meta-analysis and implications for HIV prevention, International Journal of Epidemiology, Vol: 39, Pages: 1048-1063, ISSN: 1464-3685
Background The human immunodeficiency virus (HIV) infectiousness of anal intercourse (AI) has not been systematically reviewed, despite its role driving HIV epidemics among men who have sex with men (MSM) and its potential contribution to heterosexual spread. We assessed the per-act and per-partner HIV transmission risk from AI exposure for heterosexuals and MSM and its implications for HIV prevention.Methods Systematic review and meta-analysis of the literature on HIV-1 infectiousness through AI was conducted. PubMed was searched to September 2008. A binomial model explored the individual risk of HIV infection with and without highly active antiretroviral therapy (HAART).Results A total of 62 643 titles were searched; four publications reporting per-act and 12 reporting per-partner transmission estimates were included. Overall, random effects model summary estimates were 1.4% [95% confidence interval (CI) 0.2–2.5)] and 40.4% (95% CI 6.0–74.9) for per-act and per-partner unprotected receptive AI (URAI), respectively. There was no significant difference between per-act risks of URAI for heterosexuals and MSM. Per-partner unprotected insertive AI (UIAI) and combined URAI–UIAI risk were 21.7% (95% CI 0.2–43.3) and 39.9% (95% CI 22.5–57.4), respectively, with no available per-act estimates. Per-partner combined URAI–UIAI summary estimates, which adjusted for additional exposures other than AI with a ‘main’ partner [7.9% (95% CI 1.2–14.5)], were lower than crude (unadjusted) estimates [48.1% (95% CI 35.3–60.8)]. Our modelling demonstrated that it would require unreasonably low numbers of AI HIV exposures per partnership to reconcile the summary per-act and per-partner estimates, suggesting considerable variability in AI infectiousness between and within partnerships over time. AI may substantially increase HIV transmission risk even if the infected partner is receiving HAART; however, predictions are highly sens
Boily MC, 2010, Polygyny, concurrency, its impact and lack of impact on HIV, HIV Therapy, Vol: 4, Pages: 139-144, ISSN: 1758-4310
Evaluation of: Reniers G, Watkins S: Polygyny and the spread of HIV in sub-Saharan Africa: a case of benign concurrency. AIDS 24, 299-307 (2010). This ecological study aims to understand the role of concurrency on HIV in sub-Saharan Africa. The results showed a negative association between the prevalence of HIV and polygyny, independently of selected risk factors (e.g., age at sexual debut and extramarital sex). This reflects the potential protective role of this specific form of concurrency, which contrasts with the common understanding that concurrency favors the spread of HIV. More research is needed to understand how different concurrency patterns influence the global network structure, how they are associated with risk practices within partnerships and the motivation underlying concurrency. This is relevant for the design of intervention focusing on concurrency, to maximise impact and minimize the risk of negative compensatory risk behavior. These results illustrate a growing misinterpretation of early model results due to the underappreciation of the diversity of network structures and HIV epidemic sizes that can be produced when concurrency levels are high. © 2010 Future Medicine Ltd.
Pickles M, Foss AM, Vickerman P, et al., 2010, Interim modelling analysis to validate reported increases in condom use and assess HIV infections averted among female sex workers and clients in southern India following a targeted HIV prevention programme, SEXUALLY TRANSMITTED INFECTIONS, Vol: 86, Pages: I33-I43, ISSN: 1368-4973
Baggaley RF, Petersen ML, Soares MA, et al., 2010, Human immunodeficiency virus: Resistance to antiretroviral drugs in developing countries, Antimicrobial Resistance in Developing Countries, Pages: 75-94, ISBN: 9780387893693
© 2010 Springer Science Business Media, LLC. All rights reserved. This chapter reviews issues central to understanding the emergence and transmission of drug-resistant human immunodeficiency virus (HIV) and its impact on developing countries. We first give an overview of HIV, HIV treatment using antiretroviral drugs, and access to treatment in developing countries. Then we review current understanding of the impact of adherence and treatment interruption on the emergence of resistance among treated individuals (secondary resistance) and factors contributing to secondary resistance in resource-poor settings. Transmitted (or primary) resistance, which can threaten the effectiveness of antiretroviral regimens among treatment-naïve individuals, is also discussed. Furthermore, we address how antiretroviral delivery systems in developing countries may impact resistance. Mathematical models of HIV transmission offer important insights into the course of HIV epidemics and how expanded access and policies for antiretroviral delivery in developing countries may impact resistance. We summarize the major findings from published modeling studies and discuss their predictions and limitations. We then review available empirical data on antiretroviral resistance in developing countries. Finally, we discuss the implications of these findings for policy and the monitoring of epidemic trends.
Dimitrov DT, Masse B, Boily M-C, 2010, Who will Benefit from a Wide-Scale Introduction of Vaginal Microbicides in Developing Countries?, Stat Commun Infect Dis, Vol: 2, ISSN: 1948-4690
Vaginal microbicides (VMB) are currently among the few biomedical interventions designed to help women reduce their risk of acquiring HIV infection. However, the microbicide containing antiretroviral (ARV-VMB) may lead to the development of antiretroviral resistance and could paradoxically become more beneficial to men at the population level. We developed a mathematical model to study the impact of a wide-scale population usage of VMB in a heterosexual population. Gender ratios of prevented infections and prevalence reduction are evaluated in 63 different intervention schedules including continuous and interrupted ARV-VMB use by HIV-positive women. The influence of different factors on population-level benefits is also studied through Monte Carlo simulations using parameters sampled from primary ranges representative of developing countries. Our analysis indicates that women are more likely than men to benefit from ARV-VMB use since 78-80% of the total 63,000 simulations investigated (under different parameter sets) showed a female advantage whether benefit is measured as cumulative number of infections prevented, the percentage of cumulative infections prevented, or the expected reduction in prevalence. Stratified analysis by scenarios indicates that the likelihood of a male advantage with respect to the fractions of prevented infections varies from 6% to 49% among the scenarios. It is substantial only if the risk of systemic absorption and development of resistance to ARV-VMB is high and the HIV-positive women use VMB indefinitely without interruption. Therefore, the use of ARV-VMB, with successful control measures restricting usage by HIV-positive women, is still very much a female prevention tool.
Boily MC, Buvé A, Baggaley RF, 2010, HIV transmission in serodiscordant heterosexual couples., BMJ, Vol: 340
Boily M-C, Baggaley RF, Masse B, 2009, The role of heterosexual anal intercourse for HIV transmission in developing countries: are we ready to draw conclusions?, SEXUALLY TRANSMITTED INFECTIONS, Vol: 85, Pages: 408-410, ISSN: 1368-4973
Mâsse BR, Boily M-C, Dimitrov1 D, et al., 2009, Efficacy dilution in randomized placebo-controlled vaginal microbicide trials, Emerging themes in Epidemiology, Vol: 6
BackgroundTo date different vaginal gel microbicides have been evaluated in phase 2b/3 trials, but none have demonstrated effectiveness for preventing HIV infection. Failure to demonstrate effectiveness however does not necessarily indicate that a product is truly inefficacious, as several sources of efficacy dilution may compromise our ability to identify products that may have been truly efficacious.MethodsFor four individual sources of dilution, we describe the dilution mechanisms and quantify the expected effectiveness. An overall expected effectiveness that combines all sources of dilution in a trial is derived as well.ResultsUnder conditions that have been observed in recent microbicide trials, the overall expected effectiveness assuming an active gel with true efficacy of 50% and 75% are in the range of [16%; 33%] and [28%; 50%], respectively, when considering the four major sources of dilution. In contrast the diluting effect due to adherence alone (assuming an adherence of 80%) leads to higher expected effectiveness, 40% and 60% assuming an active gel with true efficacy of 50% and 75%, respectively. Individual sources of dilution may demonstrate a small effect when evaluated independently, but the overall dilution effect in a trial with several sources of dilution can be quite substantial.ConclusionCurrently planned phase 2b/3 microbicide trials of new candidate vaginal microbicides are not immune from these shortcomings. A good understanding of dilution effects is necessary to properly interpret microbicide trial results and to identify products worthy of further development and evaluation. Greater attention should be devoted to reducing and assessing the impact of efficacy dilution and to carefully selecting the effect size in the design of future trials.
Baggaley RF, Petersen ML, Soares MA, et al., 2009, Human Immunodeficiency Virus: Resistance to antiretroviral drugs in developing countries, Antimicrobial Resistance in Developing Countries, Editors: Sosa, Byarugaba, Amábile-Cuevas, Sosa, Byarugaba, Amábile-Cuevas, Publisher: Springer, Pages: 73-94, ISBN: 9780387893693
Scattered literature is available in various forms in journals that are often not easily accessible to the affected developing countries.The objective of the ...
Masse BR, Boily M-C, Desai K, 2009, Using Mathematical Modeling to Bridge Phase 3 Microbicide Trials With Public Health Decision Making, JAIDS-JOURNAL OF ACQUIRED IMMUNE DEFICIENCY SYNDROMES, Vol: 50, Pages: 434-435, ISSN: 1525-4135
Boily M-C, Baggaley RF, Wang L, et al., 2009, Heterosexual risk of HIV-1 infection per sexual act: systematic review and meta-analysis of observational studies, LANCET INFECTIOUS DISEASES, Vol: 9, Pages: 118-129, ISSN: 1473-3099
Brisson M, Van de Velde N, Boily M-C, 2009, Economic Evaluation of Human Papillomavirus Vaccination in Developed Countries, PUBLIC HEALTH GENOMICS, Vol: 12, Pages: 343-351, ISSN: 1662-4246
Deering KN, Vickerman P, Moses S, et al., 2008, The impact of out-migrants and out-migration on the HIV/AIDS epidemic: a case study from south-west India, AIDS, Vol: 22, Pages: S165-S181, ISSN: 0269-9370
Boily M-C, Pickles M, Vickerman P, et al., 2008, Using mathematical modelling to investigate the plausibility of attributing observed antenatal clinic declines to a female sex worker intervention in Karnataka state, India, AIDS, Vol: 22, Pages: S149-S164, ISSN: 0269-9370
Chandrasekaran P, Dallabetta G, Loo V, et al., 2008, Evaluation design for large-scale HIV prevention programmes: the case of Avahan, the India AIDS initiative, AIDS, Vol: 22, Pages: S1-S15, ISSN: 0269-9370
Boily M-C, Desai K, Masse B, et al., 2008, Incremental role of male circumcision on a generalised HIV epidemic through its protective effect against other sexually transmitted infections: from efficacy to effectiveness to population-level impact, SEXUALLY TRANSMITTED INFECTIONS, Vol: 84, Pages: II28-II34, ISSN: 1368-4973
Desai K, McGreevey W, Ackers ML, et al., 2008, Modeling the potential impact of HIV chemoprophylaxis strategies among men who have sex with men in the United States: HIV infections prevented and cost-effectiveness, XVI International AIDS Conference
Desai K, Sansom SL, Ackers ML, et al., 2008, Modeling the impact of HIV chemoprophylaxis strategies among men who have sex with men in the United States: HIV infections prevented and cost-effectiveness, AIDS, Vol: 22, Pages: 1829-1839, ISSN: 0269-9370
Baggaley RF, White RG, Boily M-C, 2008, Systematic review of orogenital HIV-1 transmission probabilities, International Journal of Epidemiology, Vol: 37, Pages: 1255-1265, ISSN: 1464-3685
Background The objective was to assess the risk of HIV transmission from orogenital intercourse (OI).Methods Systematic review of the literature on HIV-1 infectiousness through OI conducted according to MOOSE guidelines for reviews of observational studies. The PubMed database and bibliographies of relevant articles were searched to July 2007.Results Of the titles, 56 214 were searched from which 10 potentially appropriate studies were identified; two additional studies were identified through bibliographies and one through discussion with experts. There were 10 included studies, providing estimates of transmission probabilities per-partner (n = 5), incidence per-partner (n = 3), per-study participant (n = 3, following initially seronegative individuals whose partners are of unknown serostatus) and per-act (n = 3). Only four of 10 studies reported non-zero estimates: two per-partner estimates (20%, 95% CI: 6–51, n = 10 and a model-based estimate, 1%, range 0.85–2.3%), one per-study participant estimate (0.37%, 95% CI: 0.10–1.34%) and one per-act estimate (0.04%, 95% CI: 0.01–0.17%). Upper bounds for the 95% CI for zero estimates tended to be relatively large due to the small study sample sizes: 9.0, 12.1 and 2.8% for per-partner; 4.7, 9.6 and 1.8 per 100 person-years for incidence per-partner; 4.4% per-study participant and 0.45 and 0.02% for per-act. Given the small number of studies, a meta-analysis was not considered appropriate.Conclusions There are currently insufficient data to estimate precisely the risk from OI exposure. The low risk of transmission evident from identified studies means that more and larger studies would be required to provide sufficient evidence to derive more precise estimates.
Dube S, Body M-C, Mugurungi O, et al., 2008, Estimating vertically acquired HIV infections and the impact of the prevention of mother-to-child transmission program in Zimbabwe - Insights from decision analysis models, JAIDS-JOURNAL OF ACQUIRED IMMUNE DEFICIENCY SYNDROMES, Vol: 48, Pages: 72-81, ISSN: 1525-4135
Boily M-C, Abu-Raddad L, Desai K, et al., 2008, Measuring the public-health impact of candidate HIV vaccines as part of the licensing process, LANCET INFECTIOUS DISEASES, Vol: 8, Pages: 200-207, ISSN: 1473-3099
Phillips AE, Boily MC, Lowndes CM, et al., 2008, Sexual identity and its contribution to MSM risk behavior in Bangaluru (Bangalore), India: the results of a two-stage cluster sampling survey., J LGBT Health Res, Vol: 4, Pages: 111-126, ISSN: 1557-4091
In India, there are categories of MSM (hijras, kothis, double-deckers, panthis and bisexuals), which are generally associated with different HIV-risk behaviors. Our objective was to quantify differences across MSM identities (n = 357) and assess the extent they conform to typecasts that prevail in policy-orientated discourse. More feminine kothis (26%) and hijras (13%) mostly reported receptive sex, and masculine panthis (15%) and bisexuals (23%) insertive anal sex. However, behavior did not always conform to expectation, with 25% and 16% of the sample reporting both insertive and receptive anal intercourse with known and unknown noncommercial partners, respectively (p < 0.000). Although behavior often complied with stereotyped role and identity, male-with-male sexual practices were fluid. Reification of these categories in an intervention context may hinder our understanding of the differential HIV risk among MSM.
Boily M-C, Lowndes CM, Vickerman P, et al., 2007, Evaluating large-scale HIV prevention interventions: study design for an integrated mathematical modelling approach, SEXUALLY TRANSMITTED INFECTIONS, Vol: 83, Pages: 582-589, ISSN: 1368-4973
Boily MC, Asghar Z, Garske T, et al., 2007, Influence of selected formation rules for finite population networks with fixed macrostructures: Implications for individual-based model of infectious diseases, MATHEMATICAL POPULATION STUDIES, Vol: 14, Pages: 237-267, ISSN: 0889-8480
Brisson M, Van de Velde N, De Wals P, et al., 2007, Estimating the number needed to vaccinate to prevent diseases and death related to human papillomavirus infection, CANADIAN MEDICAL ASSOCIATION JOURNAL, Vol: 177, Pages: 464-468, ISSN: 0820-3946
Orroth KK, Freeman EE, Bakker R, et al., 2007, Understanding the differences between contrasting HIV epidemics in east and west Africa: results from a simulation model of the Four Cities Study, SEXUALLY TRANSMITTED INFECTIONS, Vol: 83, Pages: I5-I16, ISSN: 1368-4973
Abu-Raddad LJ, Boily M-C, Self S, et al., 2007, Analytic insights into the population level impact of imperfect prophylactic HIV vaccines, JAIDS-JOURNAL OF ACQUIRED IMMUNE DEFICIENCY SYNDROMES, Vol: 45, Pages: 454-467, ISSN: 1525-4135
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