Concurrent sexual partnerships are widely believed to be one of the main drivers of the HIV epidemic in sub-Saharan Africa. But an Article published in this week's HIV Special Issue of The Lancet shows that it is overall number of sexual partners, rather than whether they are concurrent, that increases the risk of HIV transmission in a typical high prevalence African population. The Article is written by Dr Frank Tanser, Africa Centre for Health and Population Studies, University of KwaZulu-Natal, South Africa, and colleagues.
The authors used data from one of the most comprehensive demographic surveillance sites in Africa—the Africa Centre Demographic Information System (KwaZulu-Natal, South Africa). The site conducts demographic, HIV surveillance and sexual behavior surveys in a rural population of 87,000. They then constructed estimates of the geographical variation in reported concurrent and lifetime partners in 2153 sexually active men aged 15 years across the study area. After this, the researchers followed 7284 HIV-negative women (≥15 years of age) in the population and quantified the effect of the sexual behaviour profiles of men in the surrounding local community on a woman's risk of HIV acquisition.
At a local community level, a mean of 32% of sexually-active men were estimated to be in concurrent sexual partnerships (range 4% to 76%), while the mean number of lifetime partners was 6 (range 3 to 13). After adjustment for individual-level sexual behaviour and demographic, socioeconomic, and environmental factors associated with HIV acquisition, mean lifetime number of partners of men in the immediate local community was strongly predictive of risk of acquiring HIV in women, whereas a high prevalence of partnership concurrency in the same local community was not associated with any increase in risk of HIV acquisition.
The authors say: "Our data…provide no evidence to suggest that the high rate of new HIV infections is being driven by the segment of the sexually active population reporting concurrent sexual partners (29% of men and 2% of women). Our findings suggest that in similar hyperendemic sub-Saharan African settings, there is a need for clear messages aimed at the reduction of multiple partnerships, irrespective of whether those partnerships overlap in time."
But they add: "However, the absence of an effect of concurrency on HIV incidence in this setting should not be taken to necessarily mean that high levels of concurrent partnerships could not have played an important part in the initial stages of the HIV epidemic in this population or continue to play a part in other specific epidemic settings."
In a linked Comment, Professor Nancy S Padian, Office of the US Global AIDS Coordinator, US Department of State, Washington, DC, USA, University of California, Berkeley, CA, USA; and Bill and Melinda Gates Foundation, Seattle, WA, USA, and Ms Shanthi Manian, University of California, Berkeley, CA, USA, say that it is time to put the concurrency debate to rest. They conclude: "Essentially, Tanser and colleagues' study reinforces the need for simple, unambiguous prevention messages to discourage individuals from having several sexual partners, whether concurrent or not."
Dr Frank Tanser, Africa Centre for Health and Population Studies, University of KwaZulu-Natal, South Africa. T) +27-35-5507500 E) tanserf@africacentre.ac.za
Professor Nancy S Padian, Office of the US Global AIDS Coordinator, US Department of State, Washington, DC, USA, University of California, Berkeley, CA, USA. Please contact by email to arrange interview E) nancy.padian@gmail.com
Ms Shanthi Manian, University of California, Berkeley, CA, USA. T) +1 (650) 862-4621 E) shanthi.manian@gmail.com
Journal
The Lancet