Mathematical modelling for assessing HIV epidemics and the impact of interventions in Latin America

Latin America is a region of diversity, inequality, poverty and an outstanding capacity to remain stable despite these challenges. The HIV epidemic in the region resembles these same characteristics, with a wide range of risk behaviours, a disproportionate burden in vulnerable groups and yet perhaps a highly effective response. Brazil and Colombia have extensively deployed prevention strategies and delivered antiretroviral treatment and there are still further expansions in sight. However, the likely impact of these HIV programmes on the epidemic has never been evaluated. This thesis addresses these gaps by retrospectively evaluating the impact of antiretroviral treatment and prevention campaigns on new HIV infections. This is done by means of mathematical models that represent HIV transmission in these settings and which creates a counterfactual projection for the trajectory the epidemic might otherwise have taken. These estimations are interpreted in the context of ambitious plans to scale treatment further, along with a growing realisation of the long-term costs that these programmes imply. Tracking the epidemic is essential for the evaluation of programmes in the next phase of the response. To support this, a new method for incidence estimation is proposed. This method relies exclusively on case-report data, which is robust in these settings, and a flexible model specification that should be suitable for a wide range of epidemic scenarios. The parameters for the model are estimated in Bayesian framework and applied to the case study of Colombia. These resulting estimates of the historic course of the epidemic in Colombia are strikingly different to that which has previously been estimated and casts new light on the nature of epidemics in this region and the response to it that is now required. Overall, these results stand as the first analysis of this kind in the region and present useful results and methods that should support a continued effective response to HIV epidemic in this region.Open Acces