The effect of HIV, behavioural change, and STD syndromic management on STD epidemiology in sub-Saharan Africa: Simulations of Uganda
ABSTRACT An assessment was made of how the HIV epidemic may have influenced sexually transmitted disease (STD) epidemiology in Uganda, and how HIV would affect the effectiveness of syndromic STD treatment programmes during different stages of the epidemic. The dynamic transmission model STDSIM was used to simulate the spread of HIV and four bacterial and one viral STD. Model parameters were quantified using demographic, behavioural, and epidemiological data from rural Rakai and other Ugandan populations. The findings suggest that severe HIV epidemics can markedly alter STD epidemiology, especially if accompanied by a behavioural response. Likely declines in bacterial causes of genital ulcers should be considered in defining policies on syndromic STD management in severe HIV epidemics.
- SourceAvailable from: Nadia Abuelezam
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- "We found that individual-based models in the HIV transmission and prevention literature are able to answer a wide range of questions related to specific populations and interventions (Table 2). The models examined how a variety of HIV interventions such as vaccination [17-22], circumcision [23,24], condom usage [25-32], reduction in concurrency [25,26,29,32-34], HIV testing [15,28,35-37], anti-retroviral treatment [19,22,37-39], STD control [25,29,30,40-45], and prevention of mother to child transmission [18,46,47] can affect HIV incidence and prevalence in a wide variety of settings including North America [15,26,46], Australia [20,35,36] and sub-Saharan Africa [18,19,21,23-25,27,29,30,32-34,37-45,47]. These analyses were able to discuss the effects of interventions in less researched and accessible populations like MSM [15,17,20,22,26,28,35,36] and IDU [15,48]. "
ABSTRACT: Individual-based modeling is a growing technique in the HIV transmission and prevention literature, but insufficient attention has been paid to formally evaluate the quality of reporting in this field. We present reporting recommendations for individual-based models for HIV treatment and prevention, assess the quality of reporting in the existing literature, and comment on the contribution of this model type to HIV policy and prediction. We developed reporting recommendations for individual-based HIV transmission mathematical models, and through a systematic search, used them to evaluate the reporting in the existing literature. We identified papers that employed individual-based simulation models and were published in English prior to December 31, 2012. Articles were included if the models they employed simulated and tracked individuals, simulated HIV transmission between individuals in a particular population, and considered a particular treatment or prevention intervention. The papers were assessed with the reporting recommendations. Of 214 full text articles examined, 32 were included in the evaluation, representing 20 independent individual-based HIV treatment and prevention mathematical models. Manuscripts universally reported the objectives, context, and modeling conclusions in the context of the modeling assumptions and the model's predictive capabilities, but the reporting of individual-based modeling methods, parameterization and calibration was variable. Six papers discussed the time step used and one discussed efforts to maintain internal validity in coding. Individual-based models represent detailed HIV transmission processes with the potential to contribute to inference and policy making for many different regions and populations. The rigor in reporting of assumptions, methods, and calibration of individual-based models focused on HIV transmission and prevention varies greatly. Higher standards for reporting of statistically rigorous calibration and model assumption testing need to be implemented to increase confidence in existing and future modeling results.PLoS ONE 09/2013; 8(9):e75624. DOI:10.1371/journal.pone.0075624 · 3.23 Impact Factor
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- "We used STDSIM, a stochastic microsimulation model for the spread and control of HIV and other STIs   . The model simulates individuals in a dynamic network of sexual contacts, and has been extensively used to evaluate the impact of prevention and treatment interventions on HIV epidemics in Sub-Saharan African settings   . Here, we used a quantification, i.e. parameter settings, for the Hlabisa sub-district in KwaZulu-Natal, South Africa. "
ABSTRACT: The only successful HIV vaccine trial to date is the RV144 trial of the ALVAC/AIDSVAX vaccine in Thailand, which showed an overall incidence reduction of 31%. Most cases were prevented in the first year, suggesting a rapidly waning efficacy. Here, we predict the population level impact and cost-effectiveness of practical implementation of such a vaccine in a setting of a generalised epidemic with high HIV prevalence and incidence. We used STDSIM, an established individual-based microsimulation model, tailored to a rural South African area with a well-functioning HIV treatment and care programme. We estimated the impact of a single round of mass vaccination for everybody aged 15-49, as well as 5-year and 2-year re-vaccination strategies for young adults (aged 15-29). We calculated proportion of new infections prevented, cost-effectiveness indicators, and budget impact estimates of combined ART and vaccination programmes. A single round of mass vaccination with a RV144-like vaccine will have a limited impact, preventing only 9% or 5% of new infections after 10 years at 60% and 30% coverage levels, respectively. Revaccination strategies are highly cost-effective if vaccine prices can be kept below 150 US$/vaccine for 2-year revaccination strategies, and below 200 US$/vaccine for 5-year revaccination strategies. Net cost-savings through reduced need for HIV treatment and care occur when vaccine prices are kept below 75 US$/vaccine. These results are sensitive to alternative assumptions on the underlying sexual network, background prevention interventions, and individual's propensity and consistency to participate in the vaccination campaign. A modestly effective vaccine can be a cost-effective intervention in highly endemic settings. To predict the impact of vaccination strategies in other endemic situations, sufficient knowledge of the underlying sexual network, prevention and treatment interventions, and individual propensity and consistency to participate, is key. These issues are all best addressed in an individual-based microsimulation model.Vaccine 06/2011; 29(36):6100-6. DOI:10.1016/j.vaccine.2011.06.059 · 3.49 Impact Factor
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- "Mathematical modelling can be used to make these estimates. Few modelling studies have examined the relationship between HSV2 and HIV [21–25]. One study has explored the potential impact of HSV2 therapy on HIV incidence , but none have examined the impact of an HSV2 prophylactic vaccine on HIV incidence in Africa, where interventions are most needed. "
ABSTRACT: Herpes simplex virus type-2 (HSV2) infection increases HIV transmission. We explore the impact of a potential prophylactic HSV2 vaccination on HIV incidence in Africa using STDSIM an individual-based model. A campaign that achieved 70% coverage over 5 years with a vaccine that reduced susceptibility to HSV2 acquisition and HSV2 reactivation by 75% for 10 years, reduced HIV incidence by 30-40% after 20 years (range 4-66%). Over 20 years, in most scenarios fewer than 100 vaccinations were required to avert one HIV infection. HSV2 vaccines could have a substantial impact on HIV incidence. Intensified efforts are needed to develop an effective HSV2 vaccine.Vaccine 02/2009; 27(6):940-6. DOI:10.1016/j.vaccine.2008.11.074 · 3.49 Impact Factor