AIDS is caused by human immunodeficiency virus infection. When there is a break in the skin mucous membrane and comes into contact with the human immunodeficiency virus, it is easy to be infected with AIDS, and the main modes of transmission are sexual contact transmission, blood transmission, and mother-to-child transmission. HIV can be detected in the body fluids of HIV carriers, such as blood, vaginal secretions, semen, breast milk, and saliva. When having sexual intercourse, when the skin and mucous membranes are broken, and when they come into contact with the semen and vaginal secretions of HIV carriers, it is possible to be infected with AIDS. If HIV-contaminated blood and blood products are imported, it is also easy to be infected with AIDS through blood transmission, and some patients may also be infected through the use of HIV-contaminated needles and medical equipment.