FACTSHEET Women and the Biology of HIV Transmission - CATIE

FACTSHEETWomen and the Biology of HIV TransmissionThe majority of HIV infections are transmitted sexually and so most of thetransmission occurs through the genital or reproductive systems of men andwomen. In this fact sheet we review specific biological factors in women thatmake it more or less likely that HIV can be sexually transmitted. This is one of aseries of fact sheets about the biology of HIV transmission.What is the female genital tract?The female genital tract is another namefor a woman’s reproductive system. Itincludes the vagina, cervix, uterus,fallopian tubes and ovaries.Many researchers at first thought thatthe chance of acquiring HIV sexuallythrough the female genital tract wasquite low. However, a lot of the studiesdid not account for various biological andsocial risk factors that can make awoman more susceptible to HIV. Thismeans that the probability of sexuallytransmitting and acquiring HIV in the“real world” may be a lot higher than hasbeen estimated.This fact sheet gives an overview of someof the biological and social factors thatare thought to play an important role indetermining a woman’s sexual risk forHIV infection or transmission.Researchers think that most HIVtransmission in women happens throughthe vagina, the cervix and, possibly, theuterus.Why are women at greater risk of HIV?The risk of transmitting HIV from men towomen is much higher than from womento men. This is in part because of themuch larger surface area of the vaginaand cervix compared to the areas of thepenis where transmission can happen(foreskin, urethra and small tears on thehead of the penis)—see the fact sheet onHIV Transmission: an Overview.WOMEN AND THE BIOLOGYOF HIV TRANSMISSIONpage 1 of 6

have fewer obvious symptoms, andtherefore don’t get treatment until theinfection has been present for a longtime. Having an STI increases the risk ofHIV transmission in several ways:• All STIs cause inflammation of themucous membrane. Inflammation isthe body’s immune response to aninfection or irritation. When themucous membrane is inflamed, alarge number of immune cells cometo the area to fight the infection.• Many of those immune cells will beCD4+ cells or other immune cellsthat are involved in HIV transmission.In addition, when cells are fighting offan infection, they become activated.Activated CD4+ cells are more easilyinfected by HIV.• Some STIs also cause open lesions orsores, which offer an easy way for thevirus to get into the body and causean infection.Does vaginal douching have an effect onHIV transmission?Some women douche or wash the vaginaafter or before sex.Women use various combinations thatinclude water, soap, lemon juice, vinegarand antiseptics. Some of the mostcommon reasons given by women as towhy they douche are to:• clean the vagina;• rinse away blood after theirmonthly periods;• get rid of odour from the vagina;• prevent pregnancy;• reduce the risk of sexuallytransmitted infections.Research has shown that douching isnot an effective method to preventpregnancy nor does it provide protectionfrom sexually transmitted infections. Infact studies have shown that women whodouche typically have more sexualhealth problems than those that do not.One reason for this may be that douchingcan alter or kill the “friendly” bacteriathat protect the vagina. In addition, theuse of antiseptic or acidic liquids suchas rubbing alcohol or lemon juice canirritate the lining of the vagina andcan create microscopic tears that HIVcan pass through.Key pointsWomen are more likely than their malepartners to have STIs, which have beenshown to increase HIV transmission.Practices like douching can disrupt thenatural defences of a woman’s genitaltract, increasing the risk of HIVtransmission.Maintaining good vaginal andreproductive health can be an importanttool for reducing the risk of HIVtransmission. It is a good idea to gettested regularly for STIs and bacterialvaginosis, and to find ways to practicesafer sex.Other fact sheets in this series are:• HIV Transmission: an Overview;• Sexually Transmitted Infections andHIV Transmission;• HAART and HIV Transmission.CreditsAuthors: Prameet Sheth, PhD, Brook ThornycraftIllustration: Sheena Gibson2009WOMEN AND THE BIOLOGYOF HIV TRANSMISSIONpage 4 of 6

Recommended readingSexual transmissionCoombs RW, Reichelderfer PS, Landay AL. Recentobservations on HIV type-1 infection in the genitaltract of men and women. AIDS 2003;17:455.An excellent editorial review for people that wantan in-depth review of the female and male genitaltract. This paper goes into great detail explainingthe anatomy of the female genital tract and how itrelates to susceptibility to and infectiousness ofHIV infection.Quayle AJ. The innate and early immune response topathogen challenge in the female genital tract and thepivotal role of epithelial cells. Journal of ReproductiveImmunology 2002;57(1-2):61–79.A review paper that discusses the biology of thefemale genital tract and the role various cellsplay in protecting against and preventing sexuallytransmitted infections.Quinn TC, Wawer MJ, Sewankambo N, SerwaddaD, Li C, Wabwire-Mangen F, et al. Viral load andheterosexual transmission of human immunodeficiencyvirus type 1. Rakai Project Study Group. NewEngland Journal of Medicine 2000;342(13):921–929.The most comprehensive large scale studylooking at rates of HIV transmission betweensero-discordant couples (one person in a coupleis HIV positive while the other is HIV negative).One of the first studies to break down rates oftransmission by blood HIV levels.Bacterial vaginosisMyer L, Kuhn L, Stein ZA, Wright TC Jr, Denny L.Intravaginal practices, bacterial vaginosis, andwomen's susceptibility to HIV infection:epidemiological evidence and biological mechanisms.Lancet Infectious Disease 2003;5(12):786–794.This article describes factors, both biological andsocial, that may increase a woman’s susceptibilityto HIV.Hormonal contraceptivesHild-Petito S, Veazey RS, Larner JM, Reel JR, Blye RP.Effects of two progestin-only contraceptives,Depo-Provera and Norplant-II, on the vaginalepithelium of rhesus monkeys. AIDS Research andHuman Retroviruses 1998;1:S125–S130.This study examines the risk of progesteronecontraceptives on the vaginal epithelium in ananimal model. The authors found that the use ofprogesterone contraceptives was associated withsignificant thinning of the vaginal epithelium.Kaul R, Kimani J, Nagelkerke NJ, Fonck K, Ngugi EN,Keli F, et al; Kibera HIV Study Group. Monthlyantibiotic chemoprophylaxis and incidence of sexuallytransmitted infections and HIV-1 infection in Kenyansex workers: a randomized controlled trial.Journal of the American Medical Association 2004;291(21): 2555–2562.A study done initially to investigate the impact thattreating sexually transmitted infections wouldhave on HIV acquisition in Kenyan sex workers.The study found that herpes simplex virus-2 wasassociated with an increased risk of acquiring HIV.Sexually transmitted infectionsDonovan B. Sexually transmissible infections otherthan HIV. Lancet 2004;363:545–556.A review article highlighting the most prevalentsexually transmitted infections. A great read forpeople that want to know about what’s out thereand what symptoms to look for, along with someinformation on treatment options.Corbett EL, Steketee RW, Kuile FO, Latif AS,Kamali A, Hayes RJ. HIV-1/AIDS and the control ofotherinfectious diseases in Africa. Lancet 2002;359:2177–2187.This paper provides an overview of HIV/AIDS inAfrica. It gives a comprehensive review of HIVand other major diseases including malaria,tuberculosis and various STIs. It describes theimpact of the high prevalence of untreated STIsand their role in the spread of HIV-1.Fenton K, Breban R, Vardavas R, Okano J, Martin T,Aral S, Blower S. Infectious syphilis in high-incomesettings in the 21st century. Lancet InfectiousDiseases 2008;8(4):244–253.A recent review providing an outline of thecurrent state of syphilis in developed high-incomecountries. A look into social and biological aspectsunderpinning for the recent resurgence of syphilis.WOMEN AND THE BIOLOGYOF HIV TRANSMISSIONpage 5 of 6

Additional resourceThe Canadian AIDS Society’s HIV Transmission—Guidelines for assessing risk: a resource foreducators, counsellors and health care professionals(2005) is available from the CATIE Ordering Centre(http://orders.catie.ca).DisclaimerDecisions about particular medical treatments shouldalways be made in consultation with a qualifiedmedical practitioner knowledgeable about HIV-relatedillness and the treatments in question.The Canadian AIDS Treatment Information Exchange(CATIE) in good faith provides information resources tohelp people living with HIV/AIDS who wish to managetheir own health care in partnership with their careproviders. Information accessed through or publishedor provided by CATIE, however, is not to be consideredmedical advice. We do not recommend or advocateparticular treatments and we urge users to consult asbroad a range of sources as possible. We strongly urgeusers to consult with a qualified medical practitionerprior to undertaking any decision, use or action of amedical nature.We do not guarantee the accuracy or completeness ofany information accessed through or published orprovided by CATIE. Users relying on this informationdo so entirely at their own risk. Neither CATIE nor thePublic Health Agency Canada nor any of theiremployees, directors, officers or volunteers may beheld liable for damages of any kind that may resultfrom the use or misuse of any such information. Theviews expressed herein or in any article or publicationaccessed or published or provided by CATIE are solelythose of the authors and do not reflect the policies oropinions of CATIE or the official policy of the Ministerof Health Canada.Permission to reproduceThis document is copyrighted. It may be reprintedand distributed in its entirety for non-commercialpurposes without prior permission, but permissionmust be obtained to edit its content. The followingcredit must appear on any reprint: This informationwas provided by the Canadian AIDS TreatmentInformation Exchange (CATIE). For more information,contact CATIE at 1.800.263.1638.Contact CATIEby telephone1.800.263.1638416.203.7122by fax416.203.8284by e-mailinfo@catie.caon the Webwww.catie.caby mail505-555 Richmond Street WestToronto ON M5V 3B1 CanadaFunding has been provided by the Public Health Agencyof Canada.WOMEN AND THE BIOLOGYOF HIV TRANSMISSIONpage 6 of 6