Acquired Immunodeficiency Syndrome (AIDS)

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Medical Author:

Mary D. Nettleman, MD, MS, MACP

Mary D. Nettleman, MD, MS, MACP

Mary D. Nettleman, MD, MS, MACP is the Chair of the Department of Medicine at Michigan State University. She is a graduate of Vanderbilt Medical School, and completed her residency in Internal Medicine and a fellowship in Infectious Diseases at Indiana University.

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Medical Author:

Rowena A. Medina, MD

Medical Editor:

Eric S. Daar, MD

Eric S. Daar, MD

Dr. Daar received his undergraduate degree from UCLA and medical degree from Georgetown University School of Medicine. He completed an internship and residency in internal medicine at Cedars-Sinai Medical Center and his clinical and research fellowship in infectious diseases at Cedars-Sinai Medical Center and UCLA.

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Medical Editor:

Jay W. Marks, MD

Jay W. Marks, MD

Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

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• AIDS stands for "acquired immunodeficiency syndrome."
• AIDS is an advanced stage of infection with the human immunodeficiency virus (HIV). HIV usually is spread from person to person through contact with infected sexual secretions or infected blood.
• People with AIDS have weakened immune systems that make them vulnerable to selected conditions and infections.
• For people infected with HIV, the risk of progression to AIDS increases with the number of years the person has been infected. The risk of progression to AIDS is decreased by using highly effective treatment regimens called HAART.
• In people with AIDS, HAART therapy improves the immune system and substantially increases life expectancy. Many patients who are treated with HAART have near-normal life expectancies.
• HAART is a treatment that must be continued for life. It is not a cure.
• It is possible for HIV to become resistant to some of the HAART medications. The best way to prevent resistance is for the patient to take their HAART medications as directed. If the patient wants to stop a drug because of side effects, he or she should call the physician immediately.
• If a person is exposed to blood or potentially infectious fluids from a source patient with HIV, the exposed person can take medications to reduce the risk of getting HIV.
• Research is under way to try to find a vaccine and a cure for HIV.

AIDS stands for "acquired immunodeficiency syndrome." AIDS is caused by the human immunodeficiency virus (HIV) and is the most advanced stage of HIV infection.

The virus is spread through contact with infected blood or infected fluids such as sexual secretions (stage 1). Over time, the virus attacks the immune system, focusing on special cells called "CD4 cells" which are important in protecting the body from infections and cancers, and the number of these cells starts to fall (stage 2). Eventually, the CD4 cells fall to a critical level and/or the immune system is weakened so much that it can no longer fight off certain types of infections and cancers. This advanced stage of infection (stage 3) with HIV is called AIDS.

HIV is a very small virus that contains ribonucleic acid (RNA) as its genetic material. When HIV infects animal cells, it uses a special enzyme, reverse transcriptase, to turn (transcribe) its RNA into DNA. (Viruses that use reverse transcriptase are sometimes referred to as "retroviruses.") When HIV reproduces, it is prone to making small genetic mistakes or mutations, resulting in viruses that vary slightly from each other. This ability to create minor variations allows HIV to evade the body's immunologic defenses, essentially leading to lifelong infection, and has made it difficult to make an effective vaccine. The mutations also allow HIV to become resistant to medications.