HIV/AIDS in women: an expanding epidemic.

More than 20 years into the human immunodeficiency virus-type 1 (HIV-1) epidemic, women account for nearly half of the 40 million people living with HIV-1 worldwide, with an even higher proportion existing in developing countries. Social determinants of female vulnerability to HIV-1 include gender disparities, poverty, cultural and sexual norms, lack of education, and violence. Women are also more susceptible to HIV-1 because of hormonal changes, vaginal microbial ecology and physiology, and a higher prevalence of sexually transmitted diseases. Prevention strategies must address the wide range of gender inequalities that promote the dissemination of HIV-1.