It is logical to expect that an open lesion increases the risk of STD/HIV acquisition if exposed. After all, that's why herpes increases the risk of catching HIV, other things being equal. However, to my knowledge there are no data about anal fissures per se.
So is the risk higher? Probably. But when the risk of infection is extremely low, doubling the risk or even increasing it ten-fold still leaves the risk very low. The exposures you describe are such low risk that having an anal fissure probably doesn't increase it enough to lose sleep over it. Nobody has ever documented STD or HIV transmission by hand to genital (or hand to anything esle) contact; and saliva is rarely a source of infection.
I am more concerned about the risk to the massager's health than yours; i.e., the rimmer is at much higher risk than the rimmee. On that ground, you should not permit either manual or oral contact with your anal area when your fissre is active.
I hope that helps. Good luck-- HHH, MD
Thanks for the information. Just to clarify, when I said oral sex, I was not referring to rimming. I was just referring to regular oral sex where some saliva might incidentally end up in the fissure area. Would I be correct in inferring from your comments that I shouldn't worry about that?
Finally, when you say "when the fissure is active," do you mean when it is actively bleeding or just during time periods where I've been having trouble with it.
Thanks.