AIDS is the most advanced stage of HIV infection. AIDS is diagnosed when a person infected with HIV has a CD4 count of less than 200 cells/mm3 or has an AIDS-defining condition.
Also called T cells or CD4+ T cells. Infection-fighting white blood cells of the immune system. HIV destroys CD4 cells, making it harder for the body to fight infections. A CD4 count measures how well the immune system is working. A Cd4 cell count of less than 200 cells/mm3 and a person infected with HIV is indicative of AIDS. (The CD4 count of a healthy person ranges from 500 to 1,200 cells/mm3.)
The virus that causes HIV infection. HIV is a virus that attacks the immune system, putting people infected with HIV at risk for life-threatening infections. AIDS is the most advanced stage of HIV infection.