HIV-1 prevalence typically rises more rapidly at young ages in women than in men in sub-Saharan Africa. The reasons for this are thought to include the greater susceptibility of women to HIV-1 infection, and their greater exposure to infection through sexual contact with older partners.
Simon Gregson from Imperial College, London, UK, and colleagues from Zimbabwe and UNAIDS, Geneva, Switzerland, investigated the possible association between age of sexual partners among young men and women (aged younger than 25 years) in relation to HIV-1 prevalence. Using data from a field study in rural Manicaland, a province in eastern Zimbabwe, the investigators assessed the onset and degree of sexual activity, numbers of partners, concurrent partnerships, condom use, and partner characteristics from around 10,000 men and women selected from over 8200 households.
Young women formed partnerships with men 5-10 years older than themselves, whereas young men were found to have relationships with women of a similar age or slightly younger. Young men reported more partners, more infrequent sexual intercourse, and greater condom use than young women.
Simon Gregson comments: "It has long been suspected that younger women having relationships with older men contributes to the spread of HIV infection in young women in sub-Saharan Africa. However, we describe and provide empirical evidence that shows this effect in a rural population in Zimbabwe. This aspect of sexual partner networks plays a pivotal role in the persistence of major HIV epidemics because not only do large segments of successive cohorts of young women become infected through this route, but many further infections result when these women marry and have children. Breaking this link in the pattern of transmission must become a central focus of HIV prevention strategies."
Contact: Dr Simon Gregson, Department of Infectious Disease Epidemiology, Imperial College Faculty of Medicine, University of London, Norfolk Place, London W2 1PG, UK; T) +44 (0)20 7594 3279; F) +44 (0)20 7594 3927; E) s.gregson@ic.ac.uk
Journal
The Lancet