Are Lesbians Safe from HIV?

Confirmed Case of HIV Sparks Speculation, Highlight Risks

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The risk of HIV among lesbians (also referred to as women who have sex with women) has long been considered low. But as recent as 2014, there have been cases of sexual transmission between two women where no other possible route of infection.

Does this mean that the woman-to-woman sexual transmission of HIV can no longer be considered rare? Or are there specific factors that increase that potential for infection that might inform prevention strategies moving forward?

Why "Women Who Have Sex With Women?"

Women who have sex with women (WSW) is a term used to categorize females who engage in sexual activity with other females, regardless of how they identify themselves. The term was created in the 1990s by epidemiologists as a surveillance tool to better identify the route of HIV transmission and the spread of the disease through female-female sexual activity.

Prior to this, researchers were limited by the identity-based analyses, wherein women who identified as lesbian or bisexual weren't necessarily sexually active, while those who identified as straight might be sexually active with other women.

The term WSW instead focuses on behavior rather than cultural or social self-identification, thereby providing a clearer picture of HIV prevalence and, in turn, a better understanding of the implications related to HIV prevention.

HIV Infection Rates Among WSW

In the course of the history of HIV, much of the public health focus has been placed on HIV transmission among men who have sex with men (MSM), still considered among the highest risk category in most countries.

By contrast, HIV among WSW has garnered far less attention, with the common belief that, as a group, they are of negligible risk of infection.

Statistics largely support that belief. According to the U.S. Centers for Disease Control and Prevention (CDC), of the 246,461 American women infected with HIV to 2004, only 534 reported having sex exclusively with women.

Of these, 91% had at least one other key risk factor, typically injecting drug use. A similar study found that out of a million female blood donors, not one identified as HIV-positive reported sex with another woman as their sole risk factor.

Many of the investigate cases were not among women who exclusively had sex women but among those who were infected through other high-risk activities, such as sex with a bisexual male partner. A 2003 study conducted by the CDC demonstrated that, among 3,139 HIV-positive women surveyed, 14% of white women, 6% of black women, and 6% of Hispanic women acknowledged having sex with bisexual partner.

Additionally, injecting drug use among HIV-infected women was seen to be the primary route of infection in between 24% to 33% of cases.

Cases of HIV Transmission Among WSW

To date, there have been only six cases of HIV transmission among WSW in which other high risk factors were not readily identified.

In 2003, an African American woman reportedly acquired HIV from her female partner after vigorous sex using shared sex toys.

Genotypic testing confirmed a genetic match with the partner's virus. Both women had reported that their relationship was monogamous and that neither had sex with a man. As there was no evidence of injecting drug use, it was concluded that the vigorous use of sex toys resulted in transmission through blood-tinged body fluids.

Because the HIV-positive partner was on antiretroviral therapy (ART), the women believed that the risk of transmission was unlikely and did not consider using protective barriers such as dental dams or condoms.

In March 2014, the similar case was reported by the CDC in which a 46-year-old Texas woman had "likely acquired" HIV through sex with her 43-year-old, HIV-positive female partner. Genetic testing showed a 98% match to that of her partner's virus, while a number of risk factors that could have contributed to infection were excluded.

As with the earlier, both women stated that they rarely used protective barriers during sex and that their sexual contact was "rough to the point of inducing bleeding." Furthermore, the partners were said to have had unprotected sex during menses.

However, unlike the 2003 case, the HIV-positive partner had stopped receiving ART nearly two years earlier, suggesting that her elevated viral load potentiated a greater likelihood of HIV transmission. Moreover, at the start of therapy, the woman had severe weight loss and esophageal candidiasis, the latter of which is one of the CDC's definition of AIDS.

When looking at these factors in their totality, it's clear that the amalgamation of these factors created something of a "perfect storm" for infection, whereby torn or damaged mucosal membranes of the genitalia or rectum could provide easy access for HIV.

HIV Prevention Among WSW

While current evidence suggests that the risk of transmission is extremely low in WSW with no other risk factors, prevention is nevertheless considered vital. This is particularly true in women who are either having sex with an HIV-positive female partner or are uncertain about the partner's serostatus. Potential risk factors include:

  • Sharing of sex toys
  • Fisting, particularly if there is blood exposure
  • Oral sex

To ensure minimal risk, the use of condoms, fem-dom and dental dams is recommended, particularly during menstruation.

Additionally, an elevated viral load in the HIV-infection partner, whether treated or untreated, correlates to potentially higher risk. Therefore, the need of for early testing and treatment is considered key to prevention. This is especially important for serodiscordant couples, in which one partner is HIV-positive and the other is HIV-negative. Current research strongly suggests that HIV-infected persons with an undetectable viral load are 96% less likely to transmit HIV to an uninfected partner, a strategy known as treatment as prevention (TasP).

It is also recommended that the screening for sexually transmitted diseases be performed since such infections can further increase the vulnerability of vaginal mucosal tissues.

Sources:

U.S. Centers for Disease Control and Prevention (CDC). "HIV/AIDS among Women.” Atlanta, Georgia; August 2008; accessed on April 2, 2014.

Kwakwa, H. and Ghobrial, H. "Female-to-Female Transmission of Human Immunodeficiency Virus." Clinical Infectious Diseases. September 24, 2002; 36 (3):e40-e41.

Chan, S.; Thornton, L.; Chronister, K.; et al. "Likely Transmission of Female-to-Female Transmission of HIV - Texas, 2014.V Morbidity and Mortality Weekly Report (MMWR). March 14, 2014; 63(10):209-212.

Cohen, M.; Chen, Y.; McCauley, M.; et al. "Prevention of HIV-1 infection with early antiretroviral therapy." New England Journal of Medicine. August 11, 2011; 365(6):493-505.

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