Rare case of lesbian transmission of HIV reported in US

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An extremely rare case of female-to-female sexual transmission of HIV has been reported in the United States. The report concerns a 46-year-old woman who appears to have acquired HIV during a six-month monogamous HIV serodiscordant sexual relationship with a 43-year-old woman. The newly diagnosed woman had no other risk factors for HIV and phylogenetic analysis revealed that the viruses the two women have are closely related. The case is reported in the March 14 edition of Morbidity and Mortality Weekly Report.

“This report describes a case of HIV transmission likely by sexual contact between female partners,” comment the authors. “Other risk factors for HIV transmission were not reported by the newly infected woman, and the viruses infecting the two women were virtually identical.”

Confirmed cases of female-to-female transmission of HIV via sexual contact are extremely rare. However, possible modes of female-to-female transmission during sex include exposure to vaginal or other body fluids, blood from menstruation, or blood from damage sustained during rougher sex. A rare instance female-to-female sexual transmission was reported over ten year years ago and was attributed to the sharing of sex toys.


phylogenetic analysis

The comparison of the genetic sequence of the virus in different individuals in order to determine the likelihood that two or more samples are related. This involves creating a hypothetical diagram (known as a phylogenetic tree) that estimates how closely related the samples of HIV taken from different individuals are. Phylogenetic analysis is not a reliable way to prove that one individual has infected another, but may identify transmission clusters, which can be useful for public health interventions.


The fluid portion of the blood.


Refers to the mouth, for example a medicine taken by mouth.


Insertive anal intercourse refers to the act of penetration during anal intercourse. The insertive partner is the ‘top’. 


A serodiscordant couple is one in which one partner has HIV and the other has not. Many people dislike this word as it implies disagreement or conflict. Alternative terms include mixed status, magnetic or serodifferent.

The latest case was reported to US Centers for Disease Control and Prevention (CDC) in August 2012. The woman who acquired HIV regularly sold plasma to supplement her income and had a negative HIV antibody screen when donating plasma in March 2012. Shortly after, she presented to the emergency department with sore throat, fever, vomiting, lack of appetite, dry cough, diarrhoea and muscle cramps. These can be symptoms of an HIV seroconversion illness and the woman had an HIV antibody test but this was negative.

However, 18 days later, an attempt by the patient to donate plasma was refused because HIV antibodies were detected. Repeat testing confirmed the woman had HIV.

It is highly likely that the source of the patient’s infection was her female partner, who was diagnosed with HIV in 2008. The partner started antiretroviral therapy in February 2009 but stopped in November 2010, dropping out of HIV care in January 2011.

The newly diagnosed woman had no other recent risk factors for HIV. Nor were any identified in her past. She had a history of heterosexual intercourse, but not in the ten years before acquiring HIV. Three female sexual partners during the previous three years were also reported but the woman had no history of injecting drug use or other more unusual modes of HIV transmission such as tattooing, acupuncture, transfusion or transplant.

That her current female sexual partner was the likely source of her HIV infection was confirmed by a technique called phylogenetic analysis, which showed that the genetic sequences of the viruses infecting the two women were highly related.

The couple reported routinely having unprotected (using no barrier precautions) oral and vaginal contact and using insertive sex toys that were shared between them but were not shared with any other persons. They described their sexual contact as at times rough to the point of inducing bleeding in either woman. They also reported having unprotected sexual contact during the menses of either partner.

“This report describes likely female-to-female transmission of HIV-1 supported by phylogenetic analysis in a WSW [women who have sex with women] couple who had unprotected sex during a 6-month monogamous relationship,” conclude the authors. “Although rare, HIV transmission between WSW can occur. All persons at risk of HIV, including all discordant couples, should receive information regarding the prevention of HIV.”

The newly infected woman’s partner had a viral load of 69,000 copies/ml, a level that is known to be infectious. The authors therefore believe the case underscores the importance of retaining patients with diagnosed infection in long-term care, as “control of HIV infection with suppression of viral load can result in better health outcomes and a reduced chance of transmitting HIV to partners.”


Chan SK et al. Likely female-to-female sexual transmission of HIV – Texas 2012. MMWR Weekly Report, 63(10): 209-12, 2014.