AIDS is primarily caused by infection with the HIV virus, which then proliferates massively in the body. The HIV virus destroys the human immune system, leading to a significant decline in the CD4T lymphocyte system and immune function. After the loss of immune function, a series of opportunistic infections and opportunistic tumors can occur. Therefore, AIDS is actually an acquired immunodeficiency disease, mainly transmitted through sexual contact, as well as mother-to-child transmission and blood transmission.