Call for clear HIV prevention messages in South Africa
26 July 2011
The researchers conducted a study to test whether the practice of having concurrent sexual partners affected the risk of HIV infection. They asked nearly 3000 men aged 15-55 about their relationships and then monitored for five years the occurrence of HIV infection in more than 7000 women in the same area.
While the results, published in the 'Lancet' this month, confirmed that the average number of lifetime sexual partners of men was strongly predictive of the risk of HIV infection in local women, the researchers found no association between the prevalence of concurrent partnerships and HIV risk.
Concurrent sexual partnerships have been thought to be one of the primary drivers of the HIV epidemic in sub-Saharan Africa, and many HIV prevention campaigns focus on this behaviour. However, there has been no clear evidence of its significance and the new research suggests it would be better to concentrate on a simple message about the number of sexual partners.
Dr Frank Tanser, the lead author and principal investigator, said: "One of the dangers of public health messages aimed specifically at reduction of concurrent partnerships is that they may inadvertently give the impression that having many partners one after the other does not place an individual and their partners at significant risk of infection."
Among the sexually active men who participated in the study, 29 per cent reported having two or more concurrent partners. The median number of lifetime partners was reported to be five. Among the women they monitored, the researchers observed new infections at a rate of 3.6 cases per 100 women per year.
The high rates of HIV infection were no different between communities with the highest levels of male concurrency and those with the lowest. In contrast, a higher mean number of reported lifetime partners in men in the local community significantly increased the risk of new infection in women.
Dr Tanser added: "Our results clearly demonstrate the impact of multiple partnering on transmission of HIV but we find no evidence to suggest that sexual partnerships that overlap in time are playing a disproportionately large role in driving the high rate of new infections in this setting.
"The implication is that HIV prevention campaigns need straightforward, unambiguous messages aimed at the reduction of multiple partnerships irrespective of whether those partnerships overlap in time."
The study was funded by the US National Institute of Child Health and Human Development, and the Africa Centre is suppported by the Wellcome Trust. Since 2000, the Africa Centre has conducted demographic surveillance of 87 000 individuals in a rural setting. In this area, a reported 24 per cent of the population are HIV positive.
Image: 'Together'. Credit: Stevie Taylor/Wellcome Images
Tanser F et al. Effect of concurrent sexual partnerships on rate of new HIV infections in a high-prevalence, rural South African population: a cohort study. Lancet 2011;378:247-55.