August 4, 2015
AIDS stands for Acquired Immune Deficiency Syndrome. AIDS is the most advanced stage of HIV infection. The US Centers for Disease Control and Prevention (CDC) defines a person as having AIDS if she or he is living with HIV (HIV+) and has a CD4 cell count of 200 or less. The CDC has also developed a list of opportunistic infections (OIs), cancers, and conditions that are considered AIDS-defining conditions (see below). If you have HIV and one or more of these infections or conditions, you have a diagnosis of AIDS, no matter what your CD4 count is or how it changes in the future.
AIDS is also sometimes referred to as 'stage 3 HIV.' The CDC defines and uses 'stages' of HIV mainly to keep track of the amount of HIV infection in the US and to plan for prevention and care on a population level. These definitions are not meant for health providers to use in making clinical decisions for individual patients.
The World Health Organization (WHO) uses a similar staging system and set of definitions. The WHO refers to AIDS as severe HIV and calls severe HIV or AIDS 'stage 4.' Nevertheless, it defines AIDS as occurring in people living with HIV who have CD4 counts of 200 or less or one of the AIDS-defining conditions listed below (same as CDC definition).
This list of AIDS-defining conditions comes from a government report and contains medical terms. If you have any questions, contact an educator at a local AIDS service organization or call an AIDS information line such as the Project Inform National HIV/AIDS Treatment Hotline at 800-822-7422. To find services across the world, visit AIDSmap's e-atlas.