What are HIV and AIDS?
HIV, or human immunodeficiency virus, is the virus that causes AIDS. HIV attacks
the immune system by destroying CD4 positive (CD4+) T cells, a type of white blood
cell that is vital to fighting off infection. The destruction of these cells leaves
people infected with HIV vulnerable to other infections, diseases and other complications.
AIDS is the final stage of HIV infection. A person infected with HIV is diagnosed
with AIDS when he or she has one or more opportunistic infections, such as pneumonia
or tuberculosis, and has a dangerously low number of CD4+ T cells (less than 200
cells per cubic millimeter of blood).
This article was last modified in: 06/18/2012