Acquired immunodeficiency syndrome (AIDS)

Human immunodeficiency virus (HIV) is the pathogen that causes AIDS. HIV disease is the term that encompasses all of the condition’s stages—from infection to the deterioration of the immune system and the onset of opportunistic diseases. However, AIDS is still a term commonly used to refer to the immune deficiency caused by HIV. If a person with HIV infection receives a diagnosis of at least one of a set of opportunistic illnesses or has laboratory values indicating advanced disease, his or her disease is classified as HIV Stage 3 (AIDS). All 50 states, the District of Columbia, and 6 territories (American Samoa, Guam, Northern Mariana Islands, Puerto Rico, Republic of Palau, and U.S. Virgin Islands) report confirmed diagnoses of all stages of HIV infection (including AIDS) to the Centers for Disease Control and Prevention using a uniform surveillance case definition and case report form. The case reporting definitions have changed over time to incorporate a broader range of AIDS-indicator diseases and conditions and use HIV diagnostic tests to improve the sensitivity and specificity of the definition. Because of these case definition changes, AIDS estimates over time may not be comparable. (Also see Sources and Definitions, Human immunodeficiency virus [HIV] disease.)