HIV is not normally transmitted outside the body because it is mainly found in the blood, semen, vaginal secretions, chest and abdominal fluids, breast milk and cerebrospinal fluid of HIV patients, so the three most common modes of transmission are sexual contact, blood transmission and mother-to-child transmission. Sunlight and other physical stimuli can lead to inactivation of the HIV virus and loss of infectivity. Therefore, daily contact with patients with AIDS does not lead to transmission, such as shaking hands, hugging, eating together, swimming together, there is no risk of transmission, and mosquito bites have been clinically proven not to lead to transmission of AIDS.