Hi, Oral sex carries a very low risk for HIV. Masturbation is the safest among all types of sexual activities. HIV risk is negligible even if she had masturbated to an individual who had HIV infection prior to do massage for you. HIV is a highly friable virus and can not live outside the body or body fluids for not more than few seconds. She would have at least few minutes time gap between the massages and would likely to wash her hands between attending a new client or completing the massage to a client. So nothing to worry. Dr S.Murugan