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
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AIDS is caused by HIV, which destroys important immune system cells. HIV is spread through contact with HIV-infected blood or other bodily 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.
2015 Sexually transmitted diseases treatment guidelines. Centers for Disease Control and Prevention website. Available at: https://www.cdc.gov/std/tg2015/default.htm. Updated January 25, 2017. Accessed September 17, 2018.
Guide for HIV/AIDS clinical care. National Institute of Health and Human Services website. Available at: https://hab.hrsa.gov/sites/default/files/hab/clinical-quality-management/2014guide.pdf. Updated April 2014. Accessed September 17, 2018.
HIV basics. Centers for Disease Control and Prevention website. Available at: https://www.cdc.gov/hiv/basics/index.html. Updated July 23, 2018. Accessed September 17, 2018.
Overview of HIV infection. EBSCO DynaMed website. Available at: http://www.dynamed.com/topics/dmp~AN~T114424/Overview-of-HIV-infection. Updated July 31, 2018. Accessed September 17, 2018.
Last reviewed September 2018 by EBSCO Medical Review Board
David L. Horn, MD, FACP
Last Updated: 10/23/2020