No, seriously, my ex once read me something from a wee Anne Summers guide(small hardback book) saying that an arse has very little in the way of bacteria up it. She also said that she rimmed her ex, so she might have even been making it up! I never got round to reading any of those books we bought, they struck me as being a bit Ronald Dahl and never let her wonder down there with her tongue either.
I take the point about how the homosexual community was so instrumental in first spreading HIV, but it is not just promiscuity that they have always indulged in. I've never gone into the details, and certainly have no intention of doing any internet research on the topic, but I think they also quite like rough anal sex(I think they're more into black leather gear and chains than most of us).
My backside used to sometimes bleed, a doctor (consultant) advised me it was due to an "anal fissure" and wanted to "loosen me up" with a scalpal. Needless to say I never returned to that quack and the pain in the arse disappeared(I'm not referring to my ex).
I imagine there is far more risk of contracting HIV from barebacking a vagina of a girl who is menstruating or recently has been, or is soon about to ......