This is one reason that the probability of transmitting many infections is far higher from sex than by more casual means of transmission, such as non-sexual contact---touching, hugging, shaking hands----but it is not the only reason. Although mucous membranes exist in the mouth as in the genitals, many STIs seem to be easier to transmit through oral sex than through deep kissing. According to a research findings, many infections that are easily transmitted from the mouth to the genitals or from the genitals to the mouth are harder to transmit from one mouth to another. With HIV, genital fluids happen to contain much more of the pathogen than saliva. some infections labeled as STIs can be transmitted by direct skin contact. Herpes Simplex and HPV are both examples. KSHV, on the other hand, may be transmitted by deep-kissing but also when saliva is used as a sexual lubricant.