Acquired Immunodeficiency Syndrome (AIDS)

AIDS

Acquired Immunodeficiency Syndrome (AIDS), human viral disease that ravages the immune system, undermining the body’s ability to defend itself from infection and disease. Caused by the human immunodeficiency virus (HIV), AIDS leaves an infected person vulnerable to opportunistic infections—infection by microbes that take advantage of a weakened immune system. Such infections are usually harmless in healthy people but can prove life-threatening to people with AIDS. Although there is no cure for AIDS, new drugs are available that can prolong the life spans and improve the quality of life of infected people.

Transmission of HIV—the AIDS-causing virus—occurs most commonly as a result of sexual intercourse. HIV also can be transmitted through transfusions of HIV-contaminated blood or by using a contaminated needle or syringe to inject drugs into the bloodstream. Infection with HIV does not necessarily mean that a person has AIDS. Some people who have HIV infection may not develop any of the clinical illnesses that define the full-blown disease of AIDS for ten years or more. Physicians prefer to use the term AIDS for cases where a person has reached the final, life-threatening stage of HIV infection.