AIDS stands for Acquired Immune Deficiency Syndrome. It is a condition caused by the Human Immunodeficiency Virus (HIV). HIV is a virus that attacks and weakens the immune system by destroying important immune cells (CD4 or T-cells) that help the body fight infections and diseases. When HIV is left untreated, it progressively damages the immune system to the point where it can no longer effectively defend the body. At this late stage of HIV infection, the condition is called AIDS. People with AIDS have very weakened immune systems, making them highly vulnerable to opportunistic infections and certain cancers that usually do not affect healthy immune systems. Not everyone with HIV develops AIDS, especially if they start appropriate antiretroviral therapy (ART) early. ART can control the virus, helping people with HIV live long, healthy lives and prevent the progression to AIDS. In summary:

• HIV is the virus that causes the infection.
• AIDS is the advanced stage of the disease when the immune system is severely damaged.
• AIDS diagnosis is made when CD4 cell count falls below a critical level or opportunistic infections appear.
• Treatment with HIV medicine can prevent AIDS by keeping the virus suppressed.

AIDS symptoms may include rapid weight loss, extreme tiredness, fever, night sweats, and infections that take advantage of the weakened immune system.