The human immunodeficiency virus, or HIV, attacks and destroys CD4+ T cells — the cells in your body that help fend off infection and illness. AIDS(acquired immune deficiency syndrome) is the late stage of an HIV infection, when a person’s immune system is severely weakened. Without treatment, most cases of HIV infection will indeed progress to overt AIDS within several years. In fact, most experts now typically refer to “HIV/AIDS” as a single condition because it is a progression of the same virus. However, modern anti-HIV treatment is highly effective and usually prevents the progression of HIV to AIDS.