Doctoral Degrees (Mathematical Sciences)

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Browsing Doctoral Degrees (Mathematical Sciences) by Author "Bekele, Bewketu Teshale"

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    Modeling the impact of early HIV treatment on the HIV epidemic in South Africa
    (Stellenbosch : Stellenbosch University, 2016-03) Bekele, Bewketu Teshale; Ouifki, Rachid; Delva, Wim; Nyabadza, Farai; Stellenbosch University. Faculty of Science. Dept. of Mathematical Sciences
    ENGLISH SUMMARY: Amajor international randomized clinical trial fromStrategic Timing of AntiRetroviral Treatment (START) has found that HIV-infected individuals have a considerably lower risk of developing AIDS if they start taking antiretroviral drugs sooner. According to the guidelines pre-released in September 2015, the World Health Organization (WHO) recommends that ART should be initiated in all adults living with HIV at any CD4 cell count. Following previous WHO recommendations, many governments have steadily changed antiretroviral therapy (ART) guidelines over the last decade. South Africa has revised ART guidelines to increase access to treatment to 500 CD4 cell counts/mm3 or lesswith effect fromthe 1st January 2015. In ART programs, some individuals who initiate ART either fail treatment and switch regimen or dropout from ART, which might undermine the outcomes of ART programs. Thus, in the thesis, we formulated and analyzed new mathematicalmodels that assess the impact of treatment failure and dropout on ART outcomes and associated costs. The models we considered consist of partial differential equations that are structured by time since infection and time since ART roll out. Our results confirmthat early initiation of ART contributes to a steep decline in the number of new HIV infections and HIV deaths, but also show that the benefit of ART might be limited due to the impact of dropout and treatment failure. Despite the uncertainties associatedwith some of themodels’ parameters,such as ART induced sexual behavioral change and ART access rate, with the current trend of ART access rate our simulations show that HIV elimination is not possibly achievable within a decade. To achieve HIV elimination soon, ART access ratemust substantially increase, and the dropout and treatment failure rates must substantially reduce. If individuals keep dropping out of HIV treatment at current rates and they engage in risky sexual contact, HIV incidence will increase unless other intervention measures are taken. Consequently, the burden on the annual cost of providing ART will continue to increase.