As we've learned from Matthew McConaughey's character inDallas Buyers Club (and lots more actual facts - we're not basing all of our scientific knowledge on films, we promise) HIV has always been associated with gay men. In fact, when HIV was first discovered, it affected so many gay men that it was called 'gay-related immune deficiency'.
Of course that it's a gay virus is a myth. As well as affecting the gay community, intravenous drug users who share needles can develop the very fatal disease Aids, and of the 77,610 people in the UK with HIV, 48 per cent of them got the virus through heterosexual contact and 43 per cent through sex between men.
It has, however, never been found to be transmitted between two women. Until now. The Centers for Disease Control and Prevention (CDC) has just said that their research shows that one woman has contracted it from her female partner. Whenever this has happened before, there have been other risk factors present, such as recent sex with a man, intravenous drug use, tattooing, or piercing. But in this case there say there weren't any of those factors.
At the beginning of their sexual relationship, one woman was HIV-positive. According toThe LA Times, the other woman hadn't slept with a man in 10 years, and didn't engage in any of the other activity that could be considered a risk factor. As a blood donor, she was frequently tested for HIV, and after six months of their relationship, she experienced a sudden onset of various horrible symptoms. She was admitted to hospital and after various tests, she was diagnosed as HIV-positive.
In the CDC's papers, the two women said they had unprotected sex with one another, shared sex toys, would have sex while one was on their period, and sometimes would cause one another to bleed during sex - and any of these, or a combination of these, could explain how HIV was transmitted from one woman to the other.
The CDC concluded that though it is very rare for a woman to contract HIV from another woman where there haven't been other risk factors involved - this is just one infection out of the 35.3million people across the world who have HIV - it is possible.
Now, this might not directly affect you, but it does very much hit home that it's now now only gay men and drug users who can pass on the virus. Scary. And it makes the work of doctors trying to find a cure for AIDS all the more important - something that's showing positive signs. American pediatricians have said that they believe a second baby in as many weeks has been cured with heavy doses of antiretroviral drugs. A positive sign.
For more information on HIV and Aids, go to the National Aids Trust's website www.nat.org.uk.
Follow Sophie on Twitter @sophwilkinson
This article originally appeared on The Debrief.