The concentration of HIV content in saliva is so low that it does not cause transmission. The specific amount of HIV, according to the 17th edition of Nielsen Pediatrics, is less than 1 particle of HIV infection in 1 ml of saliva, so the corresponding concentration is very low. In contrast to the semen of AIDS patients, the amount of HIV in semen can reach 1 million to 10 million in 1 ml, so the comparison between the two is very obvious. Therefore, saliva does not cause transmission, but semen, vaginal secretions, chest and abdominal fluids, as well as blood and breast milk, can cause HIV transmission. HIV infection is not caused by saliva, so daily life contact with a person with HIV, such as a gentle kiss or a normal meal, will not lead to HIV transmission. However, a deep kiss with a person with AIDS, or saliva containing a small amount of blood from bleeding gums, may raise the level of HIV in saliva and may lead to transmission.