HIV transmission

Short item Published on March 15, 2017

Age-disparate relationships and HIV transmission: not as simple as it may seem

Interventions to curb age-disparate relationships (ADR) are ongoing in spite of conflicting evidence that ADR are a risk factor for HIV transmission. There is a real need to explore the prevalence of ADR and understand what they mean for HIV transmission. We must first understand and describe these relationships; second, establish a causal relationship with HIV. We recently published a paper that explores those objectives in a population of 1,922 adult men and women living in Likoma Island, Malawi.

Short item Published on March 15, 2017

Beyond risk compensation: Clusters of antiretroviral treatment users in sexual networks can modify the impact of ART on HIV incidence

Early initiation of antiretroviral therapy (ART) significantly improves the survival of people living with HIV (PLWH) and reduces HIV transmission to uninfected partners. Mathematical models suggest that treatment-as-prevention programmes could lead to HIV elimination. How the clinical efficacy of ART in preventing HIV transmission translates to real-life settings depends in large part on the capacity of HIV programmes to engage and retain PLWH. The effects of ART on HIV incidence may also depend on changes in sexual network dynamics during the course of ART scale-up which are discussed in this article.

Published on September 14, 2016 by

Connecting the dots: network data and models in HIV epidemiology

Effective HIV prevention requires knowledge of the structure and dynamics of the social networks across which infections are transmitted. These networks are most commonly comprised of chains of sexual relationships. Whereas network data have long been collected during survey interviews, new data sources have become increasingly common in recent years. In this article, we review current and emerging methods for collecting HIV-related network data, as well as modelling frameworks commonly used to infer network parameters and map potential HIV transmission pathways within the network.

Published on March 13, 2014 by

Preventing HIV transmission – a new argument for tracing patients lost to follow-up?

Loss to follow-up (LTFU) is a serious problem in most sub-Saharan African ART programmes. If ART is interrupted or reduced, HIV again progresses, and this increases the risk of opportunistic infections and, ultimately, AIDS and death. In addition, the viral load of a patient who interrupts ART will rebound, and the probability of onward transmission increases. If tracing programmes can accelerate the return of lost patients, these patients may be less likely to transmit the virus, since the period of lapsed treatment is shortened. In this study, we created a mathematical model to determine whether tracing patients LTFU from ART programs would lower the rate of HIV transmission.

Short item Published on March 13, 2014

Relationships with Young Men and Age-Mates are Considered ‘Risky’ by Women in Cape Town

Young women in relationships with older men are typically at an elevated risk for acquisition of HIV in sub-Saharan Africa. Most qualitative studies have tended to focus on why women are motivated to participate in these relationships, offering little insight into perceived risks of these relationships. Therefore we conducted a qualitative study in three urban communities in Cape Town using thematic content analysis to explore women’s perceived risks of (non-)age-disparate relationships, the benefits of dating older men, and risk perceptions that influence decisions around these relationships.

Short item Published on March 18, 2013

Biology as Population Dynamics: Heuristics for Transmission Risk

Population-type models, accounting for phenomena such as population lifetimes, mixing patterns, recruitment patterns, genetic evolution and environmental conditions, can be usefully applied to the biology of HIV infection and viral replication.  A simple dynamic model can explore the effect of a vaccine-like stimulus on the mortality and infectiousness, which formally looks like fertility, of invading Read More

Published on June 15, 2011 by

Editorial: The wind is in our sails

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.