But he feels that the real risk of oral sex is for other transmissible agents, such as syphilis and Hepatitis B., both of which are known to be transmitted by oral sex. Dr. Detels is the investigator for the Los Angeles part of the cohort. His opinion, based on research, is that if oral transmission occurs at all, it is rare. The first reference to a case of HIV oral transmission in the body of medical literature was reported in a letter to the editors of The Lancet. Dr. Bruce Voeller cited a single case of HIV transmission where oral sex was the presumed mode of transmission.
Oral sex is one of the lower risks.
Don't let anyone come in your mouth. Other case reports surface from time to time, but these reports can never have the same standing as carefully administered cohort studies. The overwhelming weight of evidence is that HIV is not transmitted by kissing or oral-genital contact. But you have to be prudent when making public health policy. Oral transmission is an extremely rare event, probably because of the inactivation of virus by saliva.