Human immunodeficiency virus (HIV) weakens a person’s immune system by destroying the body’s cells that fight disease and infection (often called T-cells or CD4 cells). Acquired immunodeficiency syndrome, or AIDS, is the most advanced stage of HIV infection. Unlike most other viruses, the human body cannot rid itself of HIV. Once you have HIV, you have it for life. While no effective cure for HIV exists, it can be controlled with proper medical care.