A 46-year-old U.S. woman has likely acquired HIV from her female partner in a rare case of female-to-female sexual transmission of the AIDS virus, the U.S. Centers for Disease Control and Prevention (CDC) reported Thursday.

Laboratory testing confirmed that the woman from Texas 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 CDC said in its Morbidity and Mortality Weekly Report.

The woman with newly acquired infection did not report any other recognized risk factors for HIV infection, such as injection drug use, tattooing, acupuncture and piercing, the agency said.

She supplemented her income by selling her plasma and first tested negative for HIV after donating plasma in March 2012. The Houston Department of Health reported the case to the CDC in August 2012.

The CDC said the likely source of the patient's new HIV infection was her 43-year-old female sex partner who tested positive for HIV in September 2008.

The couple reported routinely having unprotected sexual contact during a six-month monogamous relationship and the recently infected woman reported that her partner was her only sexual contact at that time, the agency said.