Female to Female Sexual Transmission of HIV – a Case of Public Health Importance (COPHI) Investigation

Background: Transmission of HIV between women who have sex with women (WSW) has been rare and is difficult to prove. Previous studies have shown that the most common routes of HIV transmission in WSW, are injection drug use (IDU) and heterosexual contact with men.

Methods: An epidemiologic investigation was conducted by Houston staff with CDC support to ascertain the transmission route of a woman newly infected HIV infection of a woman who claimed her only risk was 6 month monogamous relationship with a positive female partner.  The second woman has been positive since 2008 and had also discontinued her medications.

Results: Epidemiologic investigation did not identify any risk behaviors in the new case such as injection drug use, sex with men and other potential exposures. Further findings revealed she had supplemented her income by selling her plasma and had tested negative for HIV until April 2012 when she first tested positive. Laboratory testing indicated the woman had tested negative for HIV until March 2012. Twelve days later she presented herself to a hospital emergency room with flu-like symptoms and was tested negative for HIV. Eighteen days later, she attempted to sell plasma, but her HIV test came back as positive. The HIV tests were confirmed and reported to the Houston Department of Health and Human Services and to CDC. Laboratory testing of the virus revealed an over 98% genetic match to the female partner’s virus.

Conclusions: WSW HIV transmission is rare, but possible. This case illustrates the likeliness of female to female sexual transmission of HIV. Discordant couples should be aware that WSW can acquire HIV from sexual activities and therefore, should receive education and counseling regarding safer sex practices.