Alternative Names

Acquired immune deficiency syndrome

Definition of AIDS

AIDS (acquired immune deficiency syndrome) is the final stage of HIV disease, which causes severe damage to the immune system.

Causes, incidence, and risk factors

Important facts about the spread of AIDS include:


AIDS begins with HIV infection. People infected with HIV may have no symptoms for 10 years or longer, but they can still transmit the infection to others during this symptom-free period. If the infection is not detected and treated, the immune system gradually weakens and AIDS develops.

Signs and tests

The following is a list of AIDS-related infections and cancers that people with AIDS may get as their CD4 count decreases. In the past, having AIDS was defined as having HIV infection and getting one of these additional diseases. Today, according to the Centers for Disease Control and Prevention, a person may also be diagnosed as having AIDS if they have a CD4 cell count below 200 cells/mm, even if they don’t have an opportunistic infection.


There is no cure for AIDS at this time. However, a variety of treatments are available that can help keep symptoms at bay and improve the quality of life for those who have already developed symptoms.

Expectations (prognosis)

Right now, there is no cure for AIDS. It is always fatal without treatment. In the U.S., most patients survive many years after diagnosis because of the availability of HAART. HAART has dramatically increased the amount of time people with HIV remain alive.


David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School, Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc. – 5/25/2010

Tuberculosis in the lung
STDs and ecological niches
Primary HIV infection
Canker sore (aphthous ulcer)
Mycobacterium marinum infection on the hand
Dermatitis, seborrheic - close-up
Dermatitis, seborrheic on the face
Histoplasmosis, disseminated in HIV patient
Molluscum on the chest
Molluscum contagiosum on the face
Herpes zoster (shingles), disseminated

ADAM Medical Encyclopedia

Article written by

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission ( URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability.