Biological Features that Increase the Risk of Getting (Contracting) HIV
1. Presence of STI/STDs: HIV is transmitted through bodily fluids. Biological features that increase an uninfected person's contact with infected body fluids will therefore increase that person's chances of contracting HIV. One such biological feature is having a sexually transmitted infection or disease (STI/STD) that causes sores or lesions on the genitalia. STI/STDs that cause genital sores include syphilis, gonorrhea, and herpes. In some studies, people uninfected with HIV (HIV-) people with an STI/STD who had sex with an HIV+ partner were 10 times more likely to contract HIV than were HIV- people without an STI/STD (1, 2). In heterosexual vaginal intercourse, the biological risk of contracting HIV is greater for women than for men, since the vagina has larger areas of exposed, sensitive skin than does the penis, and since the HIV is more likely to survive in the vagina than on the penis.
2. Structure of the Vagina: Uninfected people may also contract HIV through the cuts and scrapes that they get during vaginal intercourse.
3. Structure of the Anus: Uninfected people may also contract HIV through the cuts and scrapes that they get during anal intercourse. In heterosexual anal intercourse, the biological risk of contracting HIV is greater for women than for men, since the anus has larger areas of exposed, sensitive skin than does the penis, and since the HIV is more likely to survive in the anus than on the penis (4, 5). Moreover, men's semen has more HIV than do women's anal fluids (5). For these same reasons, among men who have sex with men, receptive anal sex is riskier than insertive anal sex (2).
Biological Features that Increase the Risk of Giving (Transmitting) HIV
1. Presence of STI/STDs: HIV+ people with STI/STDs are more likely to shed blood and pus through genital sores, exposing their sexual partners to HIV. Additionally, the immune systems of people with STI/STDs send immune cells to these genital lesions to fight the infections there. These immune cells--CD4+ cells--are precisely the cells to which HIV attaches. As a result, HIV+ men and women with STI/STDs have many more HIV particles concentrated near their penis and vagina, respectively, than do HIV+ people without STI/STDs. For example, one study found that HIV+ men with STI/STDs had eight times more HIV in their semen than did HIV+ men without STI/STDs (2). Thus, having an STI/STD not only makes HIV+ people more likely to expose uninfected partners to their bodily fluids, it also makes their bodily fluids more contagious (that is, the fluids have more HIV particles).
2. Viral Load: Higher concentrations of HIV are found in blood and semen during the first stage of HIV disease--that is, the acute infection--than at later stages of disease (8). The more HIV a person has (that is, the greater a person's viral load), the more likely he or she is to transmit HIV to someone else.
2. Osmond, D.H. Sexual Transmission of HIV. HIV InSite Knowledge Base Chapter. Center for HIV Information, University of California, San Francisco, 1998. Retrieved on January 14, 2004 from http://www.hivinsite.com/InSite?page=kb-07-02-01#S5X.
3. Türmen, T. Gender and HIV/AIDS. International Journal of Gynecology and Obstetrics, 82: 411-418, 2003.
4. Editors. The most common opportunistic infections in women with HIV. HIV Newsline, 4(4), 1998.
5. World Health Organization (WHO). Women and HIV/AIDS (Fact Sheet No. 242). Geneva, Switzerland: World Health Organization, 2000.
6. Global Campaign for Microbicides, Women and HIV Risk. 2003. Retrieved on January 20, 2004 from http://www.global-campaign.org/womenHIV.htm.
7. Center for Health and Gender Equity. Women at Risk: Why are STIs and HIV different for women? Takoma Park Maryland (USA): Center for Health and Gender Equity, 1999.
8. Lawn, S.D., Butera, S.T., & Folks, T.M. Contribution of immune activation to the pathogenesis and transmission of human immunodeficiency virus type 1 infection. Clinical Microbiology Review, 14(4): 753-777, 2001.
9. Porco, T.C., Martin, J.N., Page-Shafer, K.A., Cheng, A., Charlebois, E., Grant, R.M., & Osmond, D.H. Decline in HIV infectivity following the introduction of highly active antiretroviral therapy. AIDS, 18(1): 81-88, 2004.
© Sociometrics Corporation, 2004