Gregson et. al. report in a Lancet that a substantial age difference between female and male sexual partners is the major determinant in the high rate of HIV infection of young girls. In their study conducted in Manicaland, Zimbabwe they examined quantitative data on the onset and degree of sexual activity, the numbers and common occurrence of sexual partners, use of condoms, sex partner characteristics, age, and HIV prevalence.

The HIV epidemic in Zimbabwe probably began to increase in the 1980s. Currently it is estimated that one in four adults are infected which could mean that a young person initiating sexual activity would have a two out of three chance of becoming HIV infected before 55 years of age.

Results of their evaluation indicated that women age 15-24 years are almost five times more likely to be HIV infected than men. HIV infection began early -- around 16 years of age while in men HIV infection occurred in the late 20s to early 30s. The factors most associated with HIV infection, in addition to the age disparity between young girls and older men, were the early onset of sexual activity and the number of sexual partners. The study highlighted several areas that should be targeted for education and behavior changes. Once having engaged in sex, most young women continue to have sex on a regular basis. Older men often reported having sex with commercial sex workers but favored young girls because they were, "less expensive" and "AIDS free" in spite of the fact that they often viewed themselves, as well as their peers, as spreading STDs. Older men were also less likely to use condoms arguing that they were an additional expense and young girls were "AIDS free." In contrast, young men were more likely to use condoms because of a weaker bargaining position and to avoid pregnancy.

A surprising observation was that consistent condom use, which was more common in casual relations, was more likely to be associated with higher rates of HIV infection. This is likely not a result of inappropriate use of condoms, or defective condoms, but rather because those with more lifetime partners (higher risk of acquiring HIV infection) report more condom use. Clearly "consistent" condom use does not mean 100 percent use.

Women who abstain from sex are more likely to do so because of fear of pregnancy while men who abstain from sex are more likely to do so because of fear of HIV transmission.

There are several disturbing conclusions that can be drawn from this study. Girls initiate sexual relations at young ages and are more likely to become HIV infected by older men who engage in risky sexual behavior. Condom use is less likely to be used in sexual relationships where the risk of HIV infection is highest (young girls and older men) and more likely when the risk of HIV infection is lower (young girls and young men). Paradoxically, consistent condom use was associated with a higher rate of HIV infection of young women perhaps because of a false sense of security that resulted in sex with men who had more lifetime partners. Many older men are aware that they and their peers are responsible for STDs but they continue to engage in sex with young women because they are less likely to have "AIDS."

The authors conclude, "breaking this link (younger women having sex with older men) in the problem of transmission must become a central focus of HIV prevention campaigns."

Indeed, factors such as those reported in this article, support observations that young women and girls are increasingly viewed as objects of "safe sex" and as they are selected for as preferred sexual partners, women will increasingly dominate the global HIV epidemic. This may also significantly increase the number of HIV infected infants and orphans.