HIV Glossary
A comprehensive glossary of HIV-related terms and definitions.
A comprehensive glossary of HIV-related terms and definitions.
Acquired Immunodeficiency Syndrome. The most severe stage of HIV infection, diagnosed when CD4 count falls below 200 cells/mm³ or when certain opportunistic infections occur.
Antiretroviral Therapy. The use of HIV medicines to treat HIV infection. ART is recommended for all people with HIV.
A measure of the number of CD4 cells (T cells) in a sample of blood. CD4 cells are a type of white blood cell that fights infection. HIV attacks and destroys CD4 cells. A normal CD4 count is 500–1,500 cells/mm³.
Human Immunodeficiency Virus. A virus that attacks the body's immune system. Without treatment, HIV can lead to AIDS.
Integrase Strand Transfer Inhibitor. A class of antiretroviral drugs that blocks the integrase enzyme, preventing HIV from inserting its genetic material into human cells. Examples: dolutegravir, bictegravir, raltegravir.
Medication-Assisted Treatment. The use of medications (such as methadone, buprenorphine, or naltrexone) combined with counseling to treat substance use disorders.
Non-Nucleoside Reverse Transcriptase Inhibitor. A class of antiretroviral drugs that binds to and alters the reverse transcriptase enzyme. Examples: efavirenz, rilpivirine, doravirine.
Nucleoside/Nucleotide Reverse Transcriptase Inhibitor. A class of antiretroviral drugs that blocks the reverse transcriptase enzyme. Examples: tenofovir, emtricitabine, abacavir, lamivudine.
An infection that occurs more frequently or is more severe in people with weakened immune systems, such as those with HIV/AIDS. Examples include Pneumocystis pneumonia (PCP), toxoplasmosis, and CMV retinitis.
Post-Exposure Prophylaxis. Emergency HIV medicine taken after a possible exposure to HIV. Must be started within 72 hours of exposure and taken for 28 days.
Protease Inhibitor. A class of antiretroviral drugs that blocks the protease enzyme, preventing HIV from maturing. Examples: darunavir, atazanavir.
Pre-Exposure Prophylaxis. HIV medicine taken by HIV-negative people to prevent getting HIV. When taken as prescribed, PrEP reduces the risk of HIV from sex by about 99%.
The period when a person first develops detectable HIV antibodies in their blood, typically 2–4 weeks after infection. A person is said to have 'seroconverted' when they test positive for HIV antibodies.
A couple in which one partner has HIV and the other does not. Also called 'serodifferent' or 'magnetic couple.'
Sexually Transmitted Infection. An infection passed from one person to another through sexual contact. Having an STI can increase the risk of getting or transmitting HIV.
Undetectable = Untransmittable. The scientific consensus that people with HIV who have an undetectable viral load cannot transmit HIV to their sexual partners.
The amount of HIV in the blood. The goal of HIV treatment is to reduce the viral load to an undetectable level (typically less than 200 copies/mL).
Having a viral load that is so low it cannot be detected by standard lab tests (typically less than 200 copies/mL). Also called having an undetectable viral load.
The time between HIV exposure and when a test can accurately detect HIV. During the window period, a person may have HIV but test negative. The window period varies by test type: NAT (10–33 days), antigen/antibody test (18–45 days), antibody test (23–90 days).