The course of HIV infection. HIV is an infection that progresses in three stages: acute HIV infection, chronic HIV infection, and AIDS. During acute infection, HIV multiplies rapidly. As acute HIV infection progresses to chronic HIV infection, HIV multiplies less rapidly and HIV levels drop. However, as chronic HIV infection advances, HIV levels increase and the number of CD4 cells decreases. Declining CD4 cell levels indicate increasing damage to the immune system. Antiretroviral therapy (ART) can prevent HIV from destroying the immune system and advancing to AIDS.