Women, Epidemiology of HIV/AIDS

Abstract

Definition Women worldwide bear a substantial burden of human immunodeficiency virus (HIV) infection, the majority attributed to heterosexual transmission. A woman's risk of HIV acquisition results from a complex intersection of biological, behav-ioral, social, and structural factors. Timely diagnosis and linkage to care and treatment can reduce morbidity and mortality as well as perinatal transmission of HIV. Effective HIV prevention efforts among women will require a synthesis of biomed-ical, behavioral, and structural approaches which address the underlying social structures (e.g., gender inequality) which promote vulnerability to HIV infection among women. HIV/AIDS in Women Globally, over 50% of all adults aged 15 years and older living with HIV are women, an estimated total of 17.8 million women in 2015 (UNAIDS 2017). The burden of HIV among women varies by geographic region of the world. The majority of HIV-infected women live in sub-Saharan Africa, which constitutes roughly 80% of the epidemic among women (UNAIDS 2017). Risk Factors for HIV Acquisition Among Women The vast majority of women (>80%) acquire HIV through sex with an HIV-infected male partner. A number of biological, behavioral, social, and structural factors shape women's risk of HIV acquisition (Fig. 1). The probability of HIV transmission per sex act depends on the susceptibility of the female partner (e.g., coinfection with other sexually transmitted infections [STIs], pregnancy status, integrity of the genital tract), the infectious-ness of the male partner (e.g., circumcision status, stage of HIV disease, HIV viral load), the mode of sex (i.e., oral, vaginal, or anal), and frequency of exposure. For example, having an STI increases the probability of HIV infection more than 17-fold per vaginal sex act, and the probability of HIV acquisition per anal sex act is more than five-fold the probability of HIV acquisition per vaginal sex act (Boily et al. 2009). The presence of multiple factors may further increase the probability of transmission. Individual behaviors, such as vagi-nal or anal sex without a condom, substance use, having multiple male sex partners, and # Springer Science+Business Media LLC 2018 T.J. Hope et al. (eds.), Encyclopedia of AIDS, https://doi.