The publication in May, with much fanfare, of the results of the HPTN 052 Randomised Control Trial of when to start HIV-positive people on ART was music to SACEMA’s ears. The trial involved HIV discordant couples. In the treatment arm, the HIV positive partner was started immediately on anti-retroviral therapy (ART); in the control arm, people were started on ART when their CD4 cell count fell below 250/µL, as currently advised by the World Health Organization. The study showed that early treatment cut transmission by 96% and the incidence of tuberculosis by 82%. Now that it is beyond dispute that treatment dramatically reduces individual infectiousness, the remaining concerns about Treatment as Prevention are operational, since we now need to determine how such large treatment programs be safely and effectively managed, and cost, since this would require a substantial up-front investment even though it will be cost-saving in the long run.
HIV evolution is sufficiently complex that intuition alone is insufficient to understand its dynamics. Mathematical models attempt to explain real events, observed or not. In this area, studies in mathematical modelling have contributed to the knowledge, for example it was through models that Perelson et al. revealed the high viral turnover in HIV infected individuals Read More
HIV studies at SACEMA have led to theoretical work on two important questions: “Can the early and aggressive use of antiretroviral therapy lead to reductions in HIV incidence?” and “Can we improve the estimation of this incidence from cross-sectional surveys?”. The latter question has focused specifically on how to optimise the use of the BED Read More
SACEMA, in collaboration with Dr. Matthew Fox of Boston University’s Department of Epidemiology and Center for Global Health and Development (CGHD), is holding a five-day short-course on advanced epidemiologic methods from 15 August to 19 August 2011 in Stellenbosch. Introductory and intermediate courses in epidemiological methods teach students the concepts needed to begin a career Read More
Randomised controlled trials (RCTs) are used to evaluate HIV prevention methods conducted among populations with a heterogeneous risk of HIV infection among individuals. This heterogeneity is an underestimated problem which should be taken into account when designing and interpreting RCTs that test prevention methods of HIV heterosexual acquisition in adult sub-Saharan African populations with a high HIV incidence. When the effects of tested interventions are rapidly reversible, the use of the crossover design instead of a parallel design should be considered.
In South Africa, the tuberculosis infector pool is growing rapidly because neither the epidemic nor the fundamentals of control are clearly understood. The central issue in the strategy to control tuberculosis in South Africa is an understanding of the nature and extent of the infector pool and the dynamics of its maintenance and expansion. The combination of the unrestricted spread of HIV and an ineffective unbalanced tuberculosis control strategy is deadly. This article gives some (historic) background on the issue of the infector pool and proposes a way forward for tuberculosis control.
The focus of this paper is to evaluate PrEP alongside ART and condom-use interventions in South Africa, informed by national HIV and demographical surveys. The age-structured model we developed pays close attention to the distribution of relative infection risks between age categories. It includes dynamical effects usually not explicitly modelled, such as age-dependent condom use and partner choice. Despite some the limitations of the model, the model offers a relatively simple approach to studying the impact of PrEP in the context of national and generalized HIV epidemics. The inclusion of an age variable offers a direct way of studying age-structured prioritising strategies.