AIDS stands for acquired immunodeficiency syndrome:
A - Acquired. This condition is acquired, meaning that a person becomes infected with it.
I - Immuno. HIV affects a person's immune system, the part of the body that fights off germs such as bacteria or viruses.
D - Deficiency. The immune system becomes deficient and does not work properly.
S - Syndrome. A person with AIDS may experience other diseases and infections because of a weakened immune system.
AIDS can develop when HIV weakens a person’s immune system so their body is no longer able to protect itself against infections and diseases that a normal immune system would fight off. As a result, an HIV positive person may show symptoms of different infections and diseases called opportunistic infections. When someone shows symptoms of one or more of these infections, they are considered to have AIDS. Different people with AIDS may experience different clinical problems, depending on what specific opportunistic infections they develop. People who are diagnosed with AIDS can recover and regain their health, but they will still be HIV positive.
Think of AIDS as advanced HIV disease. A person with AIDS has an immune system so weakened by HIV that the person usually becomes sick from one of several opportunistic infections or cancers such as PCP (a type of pneumonia) or KS (Kaposi sarcoma, a type of cancer that affects the skin and internal organs in HIV), wasting syndrome (involuntary weight loss), memory impairment, or tuberculosis. If someone with HIV is diagnosed with one of these opportunistic infections (even if the CD4 count is above 200), he or she is said to have AIDS. AIDS usually takes time to develop from the time a person acquires HIV--usually between 2 to 10 years or more.
Once a person has been diagnosed with AIDS, she or he is always considered to have AIDS, even if that person's CD4 count goes up again and/or they recover from the disease that defined their AIDS diagnosis.