In general, AIDS is not transmitted through saliva. Although antibodies can be detected in saliva, the virus is basically undetectable.
HIV is transmitted through sexual transmission, blood transmission and mother-to-child transmission. The chances of infection are very small for behaviors such as contact, eating together, kissing, etc. However, the chance of infection is relatively higher if there is a clear contact with HIV patients such as blood or condomless sex. The blood, prostate fluid, semen, vaginal secretions, cervical secretions, cerebrospinal fluid, breast milk, pleural fluid and ascites of AIDS patients all contain relatively high HIV load and are highly infectious. When exposed to the blood or body fluids of AIDS patients, HIV may enter the circulatory system of a person, which may cause infection.
To prevent AIDS, one should try to avoid contact with the above body fluids of AIDS patients, be clean and avoid unsafe sexual behavior.