Biting is just as useful today as it was 100 years ago, and just as problematic. There are all sorts of contagious maladies that may be passed through the blood and oral cavity or via open wound to open wound. Aids just happens to be a newer, highly publicized malady. It is just one more of many that you might have to face, but that alone should not be enough to sway your decision to bite or not.
If you are in a fight and are too the point of needing to bite, quite likely you are in very close quarters hand to hand (w or w/o other weapons) and likely have open wounds as does your opponent (scrapes, cuts, bloody lips or nose, etc. In other words, infection between combatants is not unlikely and biting may just be one more wound where that happens.