Licensure for manicuring does not require disclosure of AIDS. The licensed manicurist is just as likely to have AIDS as the non-licensed manicurist.
If a person hasn't been trained in proper sterilization techniques of equipment that is used on the human body all kinds of bad things can be caught from that equipment, AIDS among them. It's a stretch, I know, but not unheard of. China (and I know I'll get sh*t for this) recently had a huge problem with AIDS being passed in barber shops.