Rare female-to-female HIV case reported in US

A 46-year-old woman in the US has likely acquired HIV from her female partner in a rare case of female-to-female sexual transmission of the deadly AIDS virus, scientists say.

The woman "likely" acquired the virus during a six-month monogamous relationship with a 43-year-old HIV-positive woman in Texas, the US Centres for Disease Control and Prevention (CDC) reported.

In August 2012, the Houston Department of Health contacted CDC regarding the rare transmission of human immunodeficiency virus (HIV) likely by sexual contact between two women.

Laboratory testing confirmed that the woman with newly diagnosed HIV infection had a virus virtually identical to that of her female partner, who was diagnosed previously with HIV and who had stopped receiving antiretroviral treatment in 2010.

The woman with newly acquired infection did not report any other recognised risk factors for HIV infection, and the viruses infecting the two women had 98 per cent sequence identity in three genes.

Transmission of HIV between women who have sex with women (WSW) has been reported rarely and is difficult to ascertain.

The potential for HIV transmission by female-to-female sexual contact includes unprotected exposure to vaginal or other body fluids and to blood from menstruation, or to exposure to blood from trauma during rough sex.

Other potential exposures associated with HIV transmission in WSW that must be ruled out include injection drug use (IDU), heterosexual sex, tattooing, acupuncture, piercing, use of shared sex toys between the partners and other persons, exposure to body fluids of others, and receipt of transplants or transfusion, the report said.

The woman who acquired HIV had a history of heterosexual intercourse, but not in the 10 years before HIV infection.

She reported three female sexual partners in the preceding 5 years but said she had no IDU, receipt of tattoos, acupuncture, transfusions, transplants, or any other recognised HIV risk behaviour.

The woman supplemented her income by selling her plasma and had tested negative for HIV by HIV-1/2 enzyme immunoassay (EIA) serology screening after donating plasma in March 2012.

In April, 10 days after donating plasma, the woman went to an emergency department with a sore throat, fever, vomiting, decreased appetite, pain on swallowing, dry cough, frequent diarrhoea, and muscle cramps.

At that time, she was again tested for HIV by EIA serology screening, and the results were negative. She was treated with azithromycin for a presumed upper respiratory infection and discharged.

Eighteen days later, the woman attempted to sell plasma but was refused because she tested positive for HIV by EIA serology screening followed by an HIV-1 Western blot test.

On July 5, results of repeated EIA and Western blot tests conducted on the woman at a health clinic were positive for HIV infection.