Understanding HIV-related terminology with a glossary

A – C

ACTG: AIDS Clinical Trials Group: the largest and most prestigious network of HIV-related studies in the U.S. There is a pediatric ACTG as well as one for adults.

ACT UP: AIDS Coalition to Unleash Power, an activist group formed in 1987

acute HIV infection: recent infection (within the previous six months)

acute retroviral syndrome: symptoms that may be experienced during acute HIV infection, such as fever (including night sweats), diarrhea, nausea and vomiting, and headache

ADAP: AIDS Drug Assistance Program. State-run assistance for HIV medication and other health needs.

adherence: taking medications as they should be taken (with or without food, on time, etc.). See non-adherence.

adverse event: a negative drug side effect. A serious AE is one that is rated Grade 3–4, with 3 being “severe” and 4 being “life- threatening.”

AIDS: Acquired Immune Deficiency Syndrome. Advanced disease of HIV infection.

agent: refers to a drug

antibody: a protein that the immune system forms to fight germs and other unwanted elements entering the body. Hence, the immune system forms HIV antibodies when the virus enters the body.

antiretroviral (ARV): an HIV drug (“anti-retroviral” means a drug that treats a retrovirus, like HIV).

antiretroviral therapy (ART): HIV therapy

assay: a test

ASO: short for “AIDS service organization”

blip: refers to a temporary increase in viral load (usually within 50 to 400) that then goes back down

CD4+ T cell: a T cell with a CD4 receptor on it, HIV’s target for infection and spreading through the body. Often referred to simply as “T cell.”

clinical progression: an HIV-related event, generally refers to disease

clinical: refers to actual effects on a patient’s health. For example, “The clinical effects are still unknown.” Also refers to care that people receive in a clinic, such as lab tests.

cognitive: refers to the working of the mind

co-factor: substances, microorganisms, or characteristics of individuals that might influence the progression of a disease or the likelihood of becoming ill

contraindication: refers to things that should not go together, such as medications that can not be taken at the same time

co-morbidity: having another chronic condition besides HIV

compassionate use: the availability of an experimental drug or treatment for people who are seriously ill

CROI: Conference on Retroviruses and Opportunistic Infections, the largest HIV medical conference in the country

cytomegalovirus (CMV): a herpes virus considered an opportunistic infection. In AIDS, most commonly known for infecting the eyes, potentially leading to blindness, but can affect other organs.

D – G

discordant couple: when one person has HIV and the other doesn’t. Also called “sero-discordant.” Some argue for “magnetic,” for opposites attract, or sero-different.

discordant response: when T cells rise but viral load does not drop, or vice-versa (viral load drops but T-cells do not rise), while on therapy

drug interaction: an effect that one drug has on another; an interaction could be positive or negative

dysplasia: abnormal development in skin, bone, and other tissues. If left untreated, may lead to cancer.

etiology: the cause of a disease

expanded access program (EAP): drug made available before final FDA approval to persons in great need of it

false positive: when an HIV test mistakenly notes that someone is positive for the virus, when they are actually HIV-negative

FDA: short for U.S. Food and Drug Administration, which approves all medicines and medical devices on the market in this country

formulary: the list of drugs available through an insurance company or health program

genotype resistance test: looks at the genetic make-up of a person’s HIV to help determine what medications would work. See also phenotype resistance test.

H – M

hepatotoxicity: toxicity in the liver

HIV: human immunodeficiency virus. If left untreated, it progresses to AIDS.

holistic: looking at physical, spiritual, emotional, and mental aspects of an individual (the “whole” person)

host: the person with a disease. For example, “A variety of host factors can influence the progression of HIV.”

immune reconstitution inflammatory syndrome (IRIS): temporary illness that may occur when the immune system becomes stronger with therapy and begins to activate underlying pathogens in order to fight them

immunologic: refers to the immune system, such as “immunologic response.” In HIV therapy, “immunologic response” refers to CD4+ T cells, while “virologic response” refers to viral load.

MRSA: drug-resistant staph, stands for “methicillin-resistant Staphylococcus aureus.” Usually occurs in a hospital setting. “CA-MRSA” stands for “community-acquired MRSA.” Pronounced “mersa.”

MSM: stands for “men who have sex with men,” a category that includes males whether they consider themselves to be gay or not. Some MSM identify themselves as straight.

mutation: refers to HIV changing itself in order to get around the effects of medications (drug resistance). Usually occurs due to non-adherence, but drug-resistant virus can also be transmitted.

N – O

non-adherence: Taking medications incorrectly (especially skipping doses), or not keeping to health care needs (such as scheduled doctor visits or filling prescriptions). Very common, so let go of any shame and seek support for taking care of your health.

nurse practitioner: a nurse who can prescribe medicine

off-label: refers to the use of a medication for which it is not approved, but for which there is evidence of effectiveness

opportunistic infection (OI): caused by a microbe that can normally exist peacefully in a person’s body, but which can cause illness when the immune system is weak


Pap smear: a test that collects cells from the cervix or anus to check for cancer or pre-cancerous changes.

pathogen: a microorganism that can cause disease. Pathogens include viruses, bacteria, fungi, and parasites.

pathogenesis: origin and development of disease

person or people living with HIV (PLWH): People-first language. “Living” shifts the emphasis to the person, and  away from the disease. “PWA” for “person with AIDS” is no longer used, because individuals are more than just a disease or condition.

phenotype resistance test: a test tube measurement that puts an HIV blood sample against each of the HIV drugs to see which ones are effective against that particular individual’s virus. See also genotype resistance test.

PEP (post-exposure prophylaxis): HIV medications taken after exposure to the virus to prevent infection. Must be started within 72 hours after exposure (three days).

PrEP (pre-exposure prophylaxis): HIV medication taken before exposure to the virus to prevent infection. At this time, the only FDA-approved drug for prevention is Truvada for PrEP, taken as one pill once a day.

prophylaxis: something used as prevention. For example, condoms are a prophylaxis against disease.

protocol: in medicine, refers to the plan for a study or course of treatment

providers: healthcare professionals; may refer to other services, such as those of social workers

R – S

rapid HIV testing: an HIV test that gives results in 20 minutes

Rapid Start: starting HIV therapy right away after diagnosis, within seven days or even the same day

rebound: generally used to refer to a rising viral load (higher than the last viral load)

regimen: drug or treatment combination

renal: refers to the kidneys

reservoir: a group of immune cells in the body that contain HIV but are not actively reproducing new virus. Reservoirs can be found in internal organs and elsewhere in the body. Because they contain latent (hidden) HIV, reservoirs are a target for cure research. They are also one of the reasons why HIV treatment now starts sooner rather than later, to keep the reservoirs from developing a greater amount of virus.

resistance: the ability of microbes, including HIV, to change their structure (develop mutations). This lessens the benefits of drug therapy.

retrovirus: a virus that works “backwards,” differently from most viruses. Most viruses use their DNA to change a person’s RNA. A retrovirus uses its RNA to insert itself into a person’s DNA. HIV is a retrovirus.

salvage therapy: Therapy given when the standard treatment for a disease or condition is no longer effective and when treatment options are limited. People with HIV who have experienced toxicity and/or developed resistance to many HIV drugs receive salvage therapy.

seropositive: in HIV, means a person tests positive for the virus

serum: the clear, thin, and sticky fluid that separates from blood when it clots. Serum, not whole blood, is the actual fluid used for measuring T cells and viral load.

suppressed: “suppressed virus” is one of the goals of HIV therapy. Simply, keeping the viral load down. Usually refers to having a viral load of less than 200. The main goal is to reach undetectable levels (less than 20–50).

susceptibility: when HIV has not developed drug resistance to a medication and that medication can still effectively fight it

T – Z

TasP: See “treatment as prevention”

T cell: An immune system cell that is made in, and released from, the thymus (hence the letter “T”). Also called T-helper cells. See also CD4+ T cell.

treatment-experienced: a person who has taken antiretroviral therapy

treatment as prevention (TasP): The inability to pass on HIV through oral, anal, or vaginal sex (effectively no risk) or pregnancy, labor, and delivery (less than 1% risk) when antiviral therapy leads to undetectable viral load. Reduced risk is likely, but not yet known, when sharing injection drug equipment. See U=U.

treatment-naïve: someone who has never taken HIV medicine

undetectable: an HIV viral load below the limit of a test’s detection, generally 50. This is the primary goal of HIV therapy. Virus is still in the person’s blood, but not at a level that can be picked up by the test. See also treatment as prevention.

U=U (Undetectable Equals Untransmittable): health campaign signifying that individuals with HIV who receive antiretroviral therapy (ART) and have achieved and maintained an undetectable viral load cannot sexually transmit the virus to others

ultrasensitive assay: in viral loads, a test that measures as low as 20 copies/mL

vertical transmission: HIV infection passed on to an infant during or around the time of pregnancy, or during breastfeeding. Very rare now due to HIV therapy, even if started at the time of labor (note that breastfeeding is not recommended in the U.S. if the mother is HIV-positive).

viral load: the quantity of virus measured in blood (serum), other fluid, or tissue

virologic: in HIV, “virologic” usually refers to viral load

Sources include AIDSInfo at the National Institutes of Health. Get more definitions: aidsinfo.nih.gov/understanding-hiv-aids/glossary and theaidsinstitute.org/education/aids-101/glossary-hivaids-related-terms.