HIV Risk Factors: Why It’s Important to Get the Word Out

By Ann Marie Carias, Ph.D., Postdoctoral Fellow at Northwestern University and volunteer for C2ST and Alexandra Prokuda, Ph.D., Program Manager at C2ST

Currently, over 1 million people in the United States are living with human immunodeficiency virus (HIV) [1]. Furthermore, the Centers for Disease Control and Prevention (CDC) has estimated that approximately 50,000 persons in the United States become infected with HIV each year with approximately 21,000 persons in the United States dying each year due to the epidemic [2].  Worldwide, the story is even more tragic with over 30 million persons, aged 15-49 years living with HIV, with 2.5 million people becoming infected annually, the majority of them women [1].  Although, the number of HIV related deaths is on the decline due to antiretroviral medications and other biomedical interventions, geographical areas such as Africa have an increase in newly infected individuals, which is a cause of major concern [3-5]. Widespread failure in vaccine and microbicide trials drives home the realization that we lack a strong enough understanding of the basic mechanisms of HIV transmission to successfully develop strategies to block viral acquisition [6-10].

Despite the fact that HIV transmission rates are low for heterosexual transmission, there has been mounting data suggesting that certain biological risk factors exist that can increase the probability of HIV infection in both men and women [11]. For example, one of the greatest risk factors associated with increased HIV transmission is the presence of sexually transmitted infections (STIs), as both ulcerative and inflammatory STIs, such as HSV-2 and chlamydia, respectively, are associated with increased HIV acquisition [12, 13]. In women, another possible risk factor associated with increased HIV transmission is progesterone-dominant hormonal states. For example, both laboratory studies and clinical trials have suggested that women utilizing the progesterone-only contraceptive, Depo-Provera, or women in the luteal phase of the menstrual cycle, have an increased probability of infection [14-17]. On the other hand, in men, whether or not an individual is circumcised has been illustrated to play a large role in HIV susceptibility as numerous clinical trials have shown a reduction in the risk of HIV infection by 50-60% in circumcised individuals [4, 18, 19].

Importantly, there is still much that is unknown about HIV transmission and acquisition and a better understanding of HIV transmission events and associated risk factors is essential to interpret the results of ongoing clinical trials. More importantly, clinicians should consider these and similar evidence when treating individuals along with prescribing contraceptives to women who are at elevated HIV risk. This is especially true in Africa where STI prevalence is high amongst women and with over one-third of women being prescribed Depo-Provera [20, 21]. In this context, it is essential that women be informed of these risk factors so that they can better protect themselves from becoming infected.

C2ST’s mission is to spread scientific knowledge and literacy from the labs to the general public. Initiatives such as the Global Health Symposium help to broadcast innovative research to those that need to know it, women and men, and C2ST is proud to be partnering with this important event. Over the past year we have ramped up our Health and Wellness programming to inform Chicagoans of the research that impacts their lives. Our programming has included events on cancer, Alzheimer’s disease, aging, the BRAIN initiative, just the brain, the Zika virus, and the effects of microbiomes in our guts and in our houses, among many others.

This post is in conjunction with the 2017 Global Health Symposium event, which took place on March 10th 2017. The Symposium brought together leaders of various backgrounds to explore how innovate technologies are improving women and children’s lives. For more information on the Symposium, including videos of the panels, click here.

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2.         CDC, Estimated HIV incidence among adults and adolescents in the United States, 2007-2010, in HIV Surveillance Supplemental Report 2012.

3.         Blower, S.M., H.B. Gershengorn, and R.M. Grant, A tale of two futures: HIV and antiretroviral therapy in San Francisco. Science, 2000. 287(5453): p. 650-4.

4.         Gray, R.H., et al., Male circumcision for HIV prevention in men in Rakai, Uganda: a randomised trial. Lancet, 2007. 369(9562): p. 657-66.

5.         Velasco-Hernandez, J.X., H.B. Gershengorn, and S.M. Blower, Could widespread use of combination antiretroviral therapy eradicate HIV epidemics? Lancet Infect Dis, 2002. 2(8): p. 487-93.

6.         Halpern, V., et al., Effectiveness of cellulose sulfate vaginal gel for the prevention of HIV infection: results of a Phase III trial in Nigeria. PLoS One, 2008. 3(11): p. e3784.

7.         Skoler-Karpoff, S., et al., Efficacy of Carraguard for prevention of HIV infection in women in South Africa: a randomised, double-blind, placebo-controlled trial. Lancet, 2008. 372(9654): p. 1977-87.

8.         Van Damme, L., et al., Lack of effectiveness of cellulose sulfate gel for the prevention of vaginal HIV transmission. N Engl J Med, 2008. 359(5): p. 463-72.

9.         Watkins, D.I., et al., Nonhuman primate models and the failure of the Merck HIV-1 vaccine in humans. Nat Med, 2008. 14(6): p. 617-21.

10.       Hammer, S.M., et al., Efficacy trial of a DNA/rAd5 HIV-1 preventive vaccine. N Engl J Med, 2013. 369(22): p. 2083-92.

11.       Gray, R.H., et al., Probability of HIV-1 transmission per coital act in monogamous, heterosexual, HIV-1-discordant couples in Rakai, Uganda. Lancet, 2001. 357(9263): p. 1149-53.

12.       Quinn, T.C. and J. Overbaugh, HIV/AIDS in women: an expanding epidemic. Science, 2005. 308(5728): p. 1582-3.

13.       Wasserheit, J.N., HIV infection and other STDs: so close and yet so far. Sex Transm Dis, 1999. 26(10): p. 549-50.

14.       Chandra, N., et al., Depot Medroxyprogesterone Acetate Increases Immune Cell Numbers and Activation Markers in Human Vaginal Mucosal Tissues. AIDS Res Hum Retroviruses, 2012.

15.       Heffron, R., et al., Use of hormonal contraceptives and risk of HIV-1 transmission: a prospective cohort study. Lancet Infect Dis, 2012. 12(1): p. 19-26.

16.       Byrne, E.H., et al., Association between injectable progestin-only contraceptives and HIV acquisition and HIV target cell frequency in the female genital tract in South African women: a prospective cohort study. Lancet Infect Dis, 2016. 16(4): p. 441-8.

17.       Carias, A.M., et al., Increases in Endogenous or Exogenous Progestins Promote Virus-Target Cell Interactions within the Non-human Primate Female Reproductive Tract. PLoS Pathog, 2016. 12(9): p. e1005885.

18.       Auvert, B., et al., Randomized, controlled intervention trial of male circumcision for reduction of HIV infection risk: the ANRS 1265 Trial. PLoS Med, 2005. 2(11): p. e298.

19.       Bailey, R.C., et al., Male circumcision for HIV prevention in young men in Kisumu, Kenya: a randomised controlled trial. Lancet, 2007. 369(9562): p. 643-56.

20.       Lande, R.E., New era for injectables, in Population Reports1995, Johns Hopkins School of Public Health: Baltimore, MD.

21.       Organization, W.H., Global incidence and prevalence of selected curable sexually transmitted infections, W.H. Organization, Editor 2008.


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