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AIDSinfo Glossary Search

A - Z Index

glossary a-z index

Absolute ContraindicationAudio (En español)

When a particular treatment or procedure should not be used under any circumstance because of the severe and potentially life-threatening risks involved.

See Related Term(s):  Contraindication

Acanthosis NigricansAudio (En español)

A skin disorder characterized by velvety, light brown-to-black markings that develop mainly in the folds of the body, such as in the armpits, groin, and creases of the neck. Acanthosis nigricans can be an inherited condition or can occur as the result of an endocrine disorder, cancer, or use of certain medications.

Acquired ImmunityAudio (En español)

Immunity that develops during a person’s lifetime. There are two types of acquired immunity: active immunity and passive immunity.

See Related Term(s):  Active Immunity, Immunity, Passive Immunity

Acquired Immunodeficiency Syndrome (AIDS) Audio (En español)

A disease of the immune system due to infection with HIV. HIV destroys the CD4 T lymphocytes (CD4 cells) of the immune system, leaving the body vulnerable to life-threatening infections and cancers. Acquired immunodeficiency syndrome (AIDS) is the most advanced stage of HIV infection.

See Related Term(s):  AIDS Case Definition, HIV Progression, Human Immunodeficiency Virus

Acquired ResistanceAudio (En español)

Also known as: Secondary Resistance

When a drug-resistant strain of HIV emerges while a person is on antiretroviral therapy (ART) for the treatment of HIV infection.

See Related Term(s):  Drug Resistance, Transmitted Resistance


Also Known As: AIDS Clinical Trials Group

Active ImmunityAudio (En español)

Immunity that develops after exposure to a disease-causing infectious microorganism or other foreign substance, such as following infection or vaccination.

See Related Term(s):  Acquired Immunity, Passive Immunity

Acute HIV InfectionAudio (En español)

Also known as: Primary HIV Infection

Early stage of HIV infection that extends approximately 2 to 4 weeks from initial infection until the body produces enough HIV antibodies to be detected by an HIV antibody test. Because the virus is replicating rapidly, HIV is highly infectious during this stage of infection.

See Related Term(s):  Acute Retroviral Syndrome, HIV Progression

Acute Infection and Early Diseases Research Program (AIEDRP) Audio (En español)

A federally funded research program that studies how HIV infects humans and how the disease progresses to AIDS.

Acute Inflammatory Demyelinating Polyneuropathy

Also Known As: Guillain-Barré Syndrome

Acute Retroviral SyndromeAudio (En español)

Flu-like symptoms of acute HIV infection that may appear approximately 2 to 4 weeks after infection. Symptoms such as fever, headache, fatigue, and swollen lymph nodes can last from a few days to 4 weeks, and then subside. During the acute stage of HIV infection, many, but not all, people will have symptoms of acute retroviral syndrome.

See Related Term(s):  Acute HIV Infection


Also Known As: AIDS Drug Assistance Programs


Also Known As: AIDS Dementia Complex

AdenopathyAudio (En español)

Any disease involving swollen glands, especially the lymph nodes.

See Related Term(s):  Lymph Nodes

AdenovirusAudio (En español)

A group of viruses that use DNA as their genetic material and commonly cause respiratory and eye infections. People with weakened immune systems, including people with HIV, have a greater risk for serious complications from an adenovirus infection than people with healthy immune systems.

See Related Term(s):  Virus

AdherenceAudio (En español)

Taking medications exactly as prescribed. Poor adherence to an HIV treatment regimen increases the risk for developing drug-resistant HIV and virologic failure.

See Related Term(s):  Drug Resistance, Virologic Failure

AdjuvantAudio (En español)

A substance added to a drug to enhance the effects of the drug. Adjuvant also refers to a substance added to a vaccine to boost the body’s immune response to the vaccine.


Also Known As: Adverse Drug Reaction

Adverse Drug Reaction (ADR) Audio (En español)

Any unintended, undesirable response to a drug taken at a normal dose for normal use. Adverse drug reactions (ADRs) are classified by onset, severity, and type.

Adverse Event (AE) Audio (En español)

Any undesirable experience associated with the use of a drug or other medical product.

See Related Term(s):  Adverse Drug Reaction


Also Known As: Adverse Event

AgammaglobulinemiaAudio (En español)

Total or near-total absence of gamma globulins in the blood. Gamma globulins are a class of blood proteins that include most antibodies. Agammaglobulinemia may be due to certain genetic diseases or to acquired diseases such as HIV/AIDS.

See Related Term(s):  Gamma Globulin

Agency for Healthcare Research and Quality (AHRQ) Audio (En español)

A federally funded agency that supports research to improve the quality, safety, efficiency, and effectiveness of health care in the United States.


Also Known As: Granulocytopenia

AIDS Case DefinitionAudio (En español)

Diagnostic criteria for AIDS established by the Centers for Disease Control and Prevention (CDC). To be diagnosed with AIDS, a person with HIV must have an AIDS-defining condition or have a CD4 count less than 200 cells/mm³ (regardless of whether the person has an AIDS-defining condition).

See Related Term(s):  AIDS-Defining Condition, Acquired Immunodeficiency Syndrome, CD4 Count, Human Immunodeficiency Virus

AIDS Clinical Trials Group (ACTG) Audio (En español)

Formerly called Adult AIDS Clinical Trials Group (AACTG). Federally funded program that supports the largest network of HIV/AIDS researchers and clinical trial units in the world. AIDS Clinical Trials Group (ACTG) develops and conducts research related to HIV infection and its complications.

AIDS Dementia Complex (ADC) Audio (En español)

Also known as: AIDS Encephalopathy, HIV Encephalopathy, HIV-Associated Dementia

A progressive neurological condition associated with advanced HIV infection or AIDS. Symptoms include memory loss, slowed movements, and behavioral changes.

AIDS Drug Assistance Programs (ADAPs) Audio (En español)

Federally funded programs that provide medications and other HIV-related services to low-income, uninsured, and underinsured people with HIV/AIDS. Services of AIDS Drug Assistance Programs (ADAPs) are available in all 50 states and U.S. territories.

AIDS Education and Training Centers (AETCs) Audio (En español)

Regional centers that conduct education and training programs for health care providers who treat people living with HIV/AIDS. Training is targeted to providers who serve minority populations, the homeless, rural communities, prisoners, community and migrant health centers, and Ryan White HIV/AIDS Program-funded sites. AIDS Education and Training Centers (AETCs) serve all 50 states and many U.S. territories.

AIDS Encephalopathy

Also Known As: AIDS Dementia Complex

AIDS Service Organization (ASO) Audio (En español)

A non-governmental organization that provides services related to the prevention and treatment of HIV/AIDS.

AIDS-Defining CancerAudio (En español)

A type of cancer that when diagnosed in a person with HIV marks the development of AIDS. AIDS-defining cancers include Kaposi sarcoma, non-Hodgkin lymphoma, and invasive cervical cancer.

See Related Term(s):  Acquired Immunodeficiency Syndrome

AIDS-Defining ConditionAudio (En español)

Any HIV-related illness included in the Centers for Disease Control and Prevention’s (CDC) list of diagnostic criteria for AIDS. AIDS-defining conditions include opportunistic infections and cancers that are life-threatening in a person with HIV.

See Related Term(s):  Acquired Immunodeficiency Syndrome, Centers for Disease Control and Prevention, Opportunistic Infection

AIDS-Related CancerAudio (En español)

A type of cancer that is more likely to occur in people with HIV/AIDS than in people with healthy immune systems. AIDS-related cancers include lung cancer, anal cancer, and Hodgkin lymphoma.

See Related Term(s):  Acquired Immunodeficiency Syndrome

AIDS-Related Complex (ARC) Audio (En español)

Symptoms that signal the transition from asymptomatic HIV infection to symptomatic HIV infection (but not full-blown AIDS). Symptoms can include recurring fever, unexplained weight loss, swollen lymph glands, diarrhea, or fungal infection of the mouth.

See Related Term(s):  Acquired Immunodeficiency Syndrome, Human Immunodeficiency Virus

AIDSinfoAudio (En español)

The federal source for HIV/AIDS medical practice guidelines, clinical trials, and other research information for health care providers, researchers, people affected by HIV/AIDS, and the general public. Information is available via the Web, phone, e-mail, and postal mail.

See Related Term(s):  infoSIDA

Alanine Aminotransferase (ALT) Audio (En español)

Also known as: Serum Glutamate Pyruvate Transaminase

An enzyme found primarily in the liver. Alanine aminotransferase may be measured as part of a liver function test.

See Related Term(s):  Liver Function Test

AlbuminAudio (En español)

A protein made by the liver and found in high concentrations in blood. This protein may be measured as part of a liver function test.

See Related Term(s):  Liver Function Test

Alkaline Phosphatase (ALP) Audio (En español)

An enzyme found throughout the body, especially in the liver and bone. Alkaline phosphatase may be measured as part of a liver function test.

See Related Term(s):  Liver Function Test

AlopeciaAudio (En español)

Loss of hair. Alopecia may be an adverse effect of some antiretroviral (ARV) drugs.


Also Known As: Alkaline Phosphatase


Also Known As: Alanine Aminotransferase

American Trypanosomiasis

Also Known As: Chagas Disease

Amino AcidsAudio (En español)

The chemical building blocks of proteins.

See Related Term(s):  Peptide, Protein

AnemiaAudio (En español)

A blood disorder caused by reduced number or function of red blood cells. Symptoms may include shortness of breath, fatigue, and rapid heartbeat. HIV-associated causes of anemia include progression of HIV disease, opportunistic infections, and certain antiretroviral (ARV) drugs.

See Related Term(s):  Red Blood Cell

AnorexiaAudio (En español)

Lack or loss of appetite. Anorexia is also commonly used to refer to anorexia nervosa, which is an eating disorder.


Also Known As: Prenatal

AntepartumAudio (En español)

The time period before childbirth. Antepartum refers to the mother.

AntibioticAudio (En español)

A drug used to kill or suppress the growth of microorganisms, such as bacteria and fungi.

See Related Term(s):  Microorganism

AntibodyAudio (En español)

Also known as: Immunoglobulin

A protein produced by B lymphocytes (B cells) in response to an antigen. Antibodies bind to and help destroy antigens.

See Related Term(s):  B Lymphocyte, Humoral Immunity

AnticoagulantAudio (En español)

Also known as: Blood Thinner

A drug used to prevent the blood from clotting.

AntifungalAudio (En español)

A drug used to kill or suppress the growth of fungi.

See Related Term(s):  Fungus

AntigenAudio (En español)

Any substance that is foreign to the body and triggers an immune response. Antigens include bacteria, viruses, and allergens, such as pollen.

See Related Term(s):  Immune Response

Antigen-Antibody Complex

Also Known As: Immune Complex

Antigen-Presenting Cell (APC) Audio (En español)

A type of immune cell that enables a T lymphocyte (T cell) to recognize an antigen and mount an immune response against the antigen. Antigen-presenting cells (APCs) include macrophages, dendritic cells, and B lymphocytes (B cells).

See Related Term(s):  Antigen, Immune Response, T Lymphocyte

AntineoplasticAudio (En español)

A drug used to inhibit the growth or spread of tumors or cancer cells.

AntiprotozoalAudio (En español)

A drug used to kill or suppress the growth of protozoans.

See Related Term(s):  Protozoan

Antiretroviral (ARV) Audio (En español)

A drug used to prevent a retrovirus, such as HIV, from replicating. The term primarily refers to antiretroviral (ARV) HIV drugs.

See Related Term(s):  Drug Class, Retrovirus

Antiretroviral Pregnancy RegistryAudio (En español)

A project established to monitor prenatal exposures to antiretroviral (ARV) drugs and to detect any potential increase in the risk of related birth defects. Pregnant women exposed to ARV drugs voluntarily enroll in the Registry through their health care providers. Information provided to the Registry includes no identifying patient information.

Antiretroviral Therapy (ART) Audio (En español)

Also known as: Combination Therapy, Combined Antiretroviral Therapy, Highly Active Antiretroviral Therapy

The recommended treatment for HIV infection. Antiretroviral therapy (ART) involves using a combination of three or more antiretroviral (ARV) drugs from at least two different HIV drug classes to prevent HIV from replicating.

See Related Term(s):  Drug Class

Antiretroviral Toxic NeuropathyAudio (En español)

Nerve damage that is due to antiretroviral (ARV) drugs.

See Related Term(s):  Neuropathy

Antisense AntiviralAudio (En español)

A drug made of short segments of DNA or RNA that can bind to and alter or suppress the function of viral DNA or RNA. Antisense antivirals prevent viruses from replicating.

AntiviralAudio (En español)

A drug used to prevent the growth or replication of viruses.

See Related Term(s):  Virus


Also Known As: Antigen-Presenting Cell

Aphthous UlcerAudio (En español)

Also known as: Canker Sore

An open sore that develops on parts of the mouth (inner surface of the cheeks and lips, tongue, soft palate, or base of the gums). Although aphthous ulcers are non-contagious and non-life-threatening, they can be very painful. Aphthous ulcers are more common and more likely to reoccur in people with HIV than in people without HIV.

ApoptosisAudio (En español)

Also known as: Programmed Cell Death

The deliberate, programmed death of a cell. Apoptosis is a normal biological process that helps the body stay healthy by eliminating old or damaged cells. One of the ways that HIV infection gradually destroys the immune system is by causing apoptosis of CD4 T lymphocytes (CD4 cells).

See Related Term(s):  CD4 T Lymphocyte

Approved DrugAudio (En español)

A drug approved by the Food and Drug Administration (FDA) for sale in the United States. The extensive FDA drug approval process includes many steps, including laboratory and animal studies, clinical trials for safety and efficacy, filing of a New Drug Application by the drug manufacturer, FDA review of the application, and FDA approval or rejection of the application.

See Related Term(s):  Clinical Trial, Food and Drug Administration, New Drug Application


Also Known As: AIDS-Related Complex

Area Under the Curve (AUC) Audio (En español)

A measure of how much drug reaches a person's bloodstream in a given period of time after a dose is given. The information is useful for determining dosing and for identifying potential drug interactions.

See Related Term(s):  Drug Interaction

ArmAudio (En español)

Any of the treatment groups in a clinical trial.

See Related Term(s):  Clinical Trial

ArrhythmiaAudio (En español)

Any irregularity in rhythm or rate of the heartbeat.


Also Known As: Antiretroviral Therapy

ArthralgiaAudio (En español)

Joint pain with additional symptoms such as redness, tenderness to touch, loss of motion, or swelling. Arthralgia is a common symptom of HIV infection and may be caused by drugs used to treat HIV and opportunistic infections.

Artificial Insemination

Also Known As: Intrauterine Insemination


Also Known As: Antiretroviral


Also Known As: AIDS Service Organization

Aspartate Aminotransferase (AST) Audio (En español)

Also known as: Serum Glutamic-Oxaloacetic Transaminase

An enzyme found especially in heart, muscle, and liver cells. Aspartate aminotransferase may be measured as part of a liver function test.

See Related Term(s):  Liver Function Test

AspergillosisAudio (En español)

An infection caused by the fungus Aspergillus. Invasive aspergillosis is a serious lung infection that can spread to other parts of the body. It occurs almost exclusively in people with low blood levels of neutrophils, a type of white blood cell, and weakened immune systems. Invasive aspergillosis in a person with HIV is rare.

See Related Term(s):  Opportunistic Infection


Also Known As: Aspartate Aminotransferase

AstheniaAudio (En español)

Weakness; lack or loss of energy or strength.

Asymptomatic HIV InfectionAudio (En español)

Also known as: Clinical Latency

Stage of HIV infection during which there are no symptoms of HIV infection. During this stage of HIV infection, which varies in length of time from person to person, HIV slowly destroys the immune system. Antiretroviral therapy (ART) can prevent the onset of symptomatic HIV infection and AIDS.

See Related Term(s):  HIV Progression

AtaxiaAudio (En español)

Impaired coordination of voluntary muscle movements. Ataxia may be an adverse effect of drugs used to treat either HIV or opportunistic infections or may be caused by neurological conditions associated with HIV.

AtherosclerosisAudio (En español)

The gradual build-up of plaque inside of artery walls. (Plaque is made up of fat, cholesterol, calcium, and other substances found in blood.) Over time, the plaque hardens and narrows the arteries, decreasing the flow of oxygen-rich blood to organs and other parts of the body.


Also Known As: Live Attenuated


Also Known As: Area Under the Curve

Autoimmune DisorderAudio (En español)

A condition that occurs when the immune system mistakenly attacks and destroys healthy body tissue. Autoimmune disorders may be caused by drugs used to treat opportunistic infections.

See Related Term(s):  Immune System

Avascular Necrosis (AVN) Audio (En español)

Death of bone tissue (osteonecrosis) due to a lack of blood supply. Avascular necrosis (AVN) most commonly affects the hip. Symptoms include pain in the affected area of the body, limited range of motion, joint stiffness, muscle spasms, and limping. AVN is associated with several medical conditions, including cancer and HIV infection.

See Related Term(s):  Osteonecrosis


Also Known As: Avascular Necrosis