Concurrent partnerships did not increase risk for HIV transmission in South Africa

Issue: August 2011

Evidence did not support the belief that concurrent sexual partnerships are an important driver of the spread of HIV infection in sub-Saharan Africa. Rather, the overall number of sexual lifetime partners increased the risk for transmission of HIV, according to a recent study conducted in a high prevalence rural South African community.

“Our results clearly demonstrate the impact of multiple partnering on transmission of HIV, but we found no evidence to suggest that sexual partnerships that overlap in time (concurrent sexual partnerships) are playing a disproportionately large role in driving the high rate of new infections in this setting,” Frank Tanser, PhD,of the University of KwaZulu-Natal, in South Africa, told Infectious Disease News. “The implication is that HIV prevention campaigns in similar hyper-endemic settings need straightforward, unambiguous messages aimed at the reduction of multiple partnerships irrespective of whether those partnerships overlap in time.”

Frank Tanser, PhD

In the population-based cohort study, Tanser and colleagues pooled data from the Africa Center demographic surveillance site and estimated the geographical variation in reported concurrent and lifetime partners among 2,153 sexually active men aged 15 to 55 years.

HIV-negative women (n=7,284), aged 15 years and older, were subsequently followed. Researchers measured the association between the sexual behavior profiles of men in the surrounding local community and the risk for acquiring HIV in women.

Approximately 23% of men reported concurrent partners in 2004; 28.9% of men who reported being sexually active reported two or more concurrent partners; 693 new female HIV infections were found (3.6/100 person-years).

The researchers measured substantial geographical variations in male sexual behavior across the study area. Mean lifetime number of partners of men (average 6.3) in the immediate local community independently predicted the risk for HIV in women (HR=1.08; 95% CI, 1.03-1.14). Conversely, a high prevalence of partnership concurrency in the same community was not associated with any increased risk for HIV (HR=1.02; 95% CI, 0.95-1.09), according to the report. The results were robust to differing definitions of the “local community” and held after adjusting for important behavioral, socio-demographic and environmental factors associated with a woman’s risk of acquiring HIV, Tanser said.

“The lack of a positive concurrency finding in the setting in which the study was conducted should not be taken to necessarily mean that high levels of concurrent partnerships could not have played a significant role in the initial stages of the HIV epidemic in this population or continue to play a role in other specific epidemic settings,” Tanser said. “Therefore, it will be important to apply these methods to other settings where the local epidemiology of HIV differs.”

In an accompanying editorial, Nancy S. Padian, PhD, and Shanthi Manian, both from the University of California, Berkeley, wrote: “The overarching finding was that increases in lifetime numbers of partners for men, not concurrency, raised the individual risk of seroconversion in women from the same area.” – by Ashley DeNyse

For more information:

Padian NS. Lancet. 2011;378:203-204.

Tanser F. Lancet. 2011;378:247-255.

Disclosure: The study was funded by the US National Institute of Child Health and Human Development; Wellcome Trust. The researchers report no relevant financial disclosures.

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