The US Centers for Disease Control and Prevention reported Thursday that a 46-year-old woman from Texas has "likely acquired" HIV virus from her female sexual partner.

Cases of female to female HIV (human immunodeficiency virus) transmission are rare. Then, there is always a possibility that the woman got the virus from drug injections rather than sexual contact with her female partner, Livescience reported.

"Transmission of HIV between women who have sex with women has been reported rarely and is difficult to ascertain," CDC officials said in a report.

The woman, whose name was not revealed, hasn't been in a heterosexual relationship for the past ten years, AFP reported. Her 43-year-old female partner has been HIV positive since 2008 and stopped taking antiretroviral therapy in 2010. Genetic analysis of virus strains from both the women showed that they were 98 percent similar.

Details of the case study have been published in the CDC's Weekly Morbidity and Mortality Weekly Report titled "Likely Female-to-Female Sexual Transmission of HIV - Texas, 2012."

The woman from Texas said that she wasn't involved in any other behavior that could increase her risk of HIV such as tattooing, body piercing or injection drug use. Her HIV status was detected when she tried to sell her plasma April 2012, CDC said.

According to the report, the women engaged in unprotected oral and vaginal sex. They shared sex toys and had intercourse during menses. The recently-infected woman has maintained that she hasn't had sexual contact with other women during the six months before her diagnosis.

"All persons at risk for HIV, including all discordant couples, should receive information regarding the prevention of HIV and sexually transmitted infections to prevent the HIV-negative partner from acquiring the infection," CDC said.

Some 34 million people in the world are now living with HIV. Of these, some 54 percent people have access to antiretroviral therapy, according to World Health Organization.

In related news, researchers have developed a post-sex gel that could offer women protection against HIV. Researchers tested the gel on female monkeys and their study is published in Science Translational Medicine.