HIV This Week

Do behavioural differences help to explain variations in HIV prevalence in adolescents in sub-Saharan Africa?

Chapman R, White RG, Shafer LA, Pettifor A, Mugurungi O, Ross D, Pascoe S, Cowan FM, Grosskurth H, Buve A, Hayes RJ. Trop Med Int Health. 2010;15:554-66

The objective of the study was to compare adolescent risk factors for HIV infection in two countries with high adolescent HIV prevalence and two lower prevalence countries with the aim of identifying risk factors that may help explain differences in adolescent HIV prevalence. Data were available from two nationally representative surveys (South Africa, Zimbabwe), two behavioural intervention trials (Tanzania, Zimbabwe) and one population-based cohort (Uganda). Data on variables known or postulated to be risk factors for HIV infection were compared. Few risk behaviours were markedly more common in the high HIV prevalence populations. Risk factors more common in high HIV prevalence settings were genital ulcers and discharge, and women were more likely to report older male partners. Age mixing may be an important determinate of HIV prevalence in adolescents. Potential reasons for the general lack of association between other adolescent risk factors and adolescent HIV prevalence include adult HIV prevalence, misreported behaviour, different survey methods and other unmeasured adolescent behaviours. If adult factors dominate adolescent HIV risk, it would help explain the failure of behavioural interventions targeted at adolescents and suggests future interventions should include adults.

For abstract access click here:

http://www.ncbi.nlm.nih.gov/pubmed/20345559

Editors’ note: This was a challenging analysis as the study results examined here were from surveys of adolescent sexual behaviour that were not designed to be compared. Statistical tests were not used because even small differences in these large data sets might be statistically significant. Nonetheless, the question is intriguing. Why does adolescent HIV prevalence vary so much among these four countries in eastern and southern Africa? Differences in risk behaviour, including, for example, age at first sex, lifetime number of sexual partners, condom use, and forced sex did not explain differences in adolescent HIV prevalence – and, in some cases, risk behaviour was higher in low prevalence populations. What the data do suggest though is that greater age differences between partners, and particularly between younger women and older men, may be playing a critical role in high adolescent HIV prevalence settings. The working hypothesis then is that higher HIV prevalence in adult populations is referred down to younger people through age-disparate sexual partnerships. Encouraging ‘sexual endogamy’, i.e. choosing partners your own age, is a challenging message for young people but one that deserves more attention.