AIDS is an acquired immunodeficiency syndrome with a variable incubation period, averaging 5-10 years. AIDS is a chronic infectious disease caused by the human immunodeficiency virus HIV, and the main modes of transmission include sexual contact, blood and mother-to-child transmission. The incubation period, or asymptomatic infection period, is the period from the onset of HIV infection to the onset of AIDS symptoms, which can be as short as a few months or as long as 15-20 years, with an average of 5-10 years. Patients with HIV latent infection do not have any symptoms, but can be tested positive for HIV antibodies and are infectious. If there is a history of high-risk HIV exposure, blood tests for HIV antibodies and antigens can be performed, and patients who are clearly infected should start antiretroviral treatment early. In addition, in case of high-risk behavior or occupational exposure, drug blockade can be performed immediately within 24 hours and up to 72 hours to prevent HIV infection.