Conditions InDepth: AIDS

Acquired immunodeficiency syndrome (AIDS) is an illness that weakens the body's immune system. The immune system of a person with AIDS is not able to fight off certain infections and cancers.

The Immune System

© 2008 Nucleus Medical Art, Inc.

AIDS is caused by the human immunodeficiency virus (HIV), which destroys important immune system cells. HIV is spread through contact with HIV-infected blood or other body fluids including semen, vaginal fluid, and breast milk. Unprotected sex is the most common mode of transmission. Sharing needles for injecting drugs is another common way the virus is transferred.

In 2006, more than one million persons are living with HIV/AIDS in the United States, and an estimated 40,000 new HIV infections are expected to occur this year. Since the first cases of acquired immunodeficiency syndrome (AIDS) were reported in 1981, infection with human immunodeficiency virus (HIV) has grown to pandemic proportions, resulting in an estimated 65 million infections worldwide, and 25 million deaths

What are the risk factors for AIDS?
What are the symptoms of AIDS?
How is AIDS diagnosed?
What are the treatments for AIDS?
Are there screening tests for AIDS?
How can I reduce my risk of AIDS?
What questions should I ask my healthcare provider?
What is it like to live with AIDS?
Where can I get more information about AIDS?


Centers for Disease Control and Prevention website. Available at: .

National Institute of Allergy and Infectious Diseases website. Available at: .

UN AIDS website. Available at:

Centers for Disease Control and Prevention. Pneumocystis pneumonia—Los Angeles. MMWR Morb Mortal Wkly Rep. 1981;30:250-252.

Joint United Nations Programme on HIV/AIDS (UNAIDS). 2006 Report on the Global AIDS Epidemic. Geneva, Switzerland: UNAIDS; 2006.

Last reviewed January 2007 by Jill D. Landis, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

Your Health and Happiness