HIV/AIDS Glossary

Acquired Immunodeficiency Syndrome (AIDS): A disease of the immune system caused by the human immunodeficiency virus (HIV). When someone has AIDS, their CD4 cells die. This exposes the body to life-threatening infections.

Adherence: The ability to follow a prescribed treatment regimen. It means taking the right dose of a drug at the right time, as directed. Failure to adhere to an HIV treatment regimen can lead to treatment failure and drug resistance.

Antiretroviral Therapy: Treatment with drugs that keep viruses from multiplying in the body. The antiretroviral therapy recommended for HIV infection is known as highly active antiretroviral therapy (HAART).

CD4 Cell: A type of white blood cell that fights infections. The more CD4 cells a person has, the healthier their immune system is. HIV infects and kills CD4 cells, weakening the immune system.

CD4 Cell Count: The number of CD4 cells in a blood sample. Helps healthcare professionals decide when to begin HIV therapy and may show whether treatment is working. A normal CD4 cell count is usually between 500 and 1400.

Clinical Trial: A research study that uses human volunteers to help find new treatments for diseases and conditions. Clinical trials may be prospective (studying data from a time point forward) or retrospective (studying data from a point in the past).

Combination Therapy: 2 or more drugs used together to control HIV infection. An example of combination therapy is the use of 2 NRTIs plus a PI or an NNRTI.

Dose: The amount of a medicine that should be taken during a given time period.

Drug Class: A group of drugs that have certain things in common and work in a similar way.

Drug-Drug Interaction: May happen when one drug is taken with another drug. Can cause a change in the way either drug works. It may also cause a side effect that does not normally happen with either drug alone.

Drug Resistance: When infections adapt to a drug and continue to multiply. This may happen even when someone is taking meds that would normally fight the infection.

First-Line Regimen: The treatment plan and drugs used when someone is taking medication for an illness for the first time.

Highly Active Antiretroviral Therapy (HAART): Treatment regimens that stop or slow the HIV virus from reproducing and keep HIV disease from progressing. The usual HAART regimen combines three or more HIV drugs from at least two different classes.

Human Immunodeficiency Virus (HIV): The virus that causes AIDS. HIV-1 causes most HIV infections throughout the world. HIV-2 is found mostly in Africa.

Immune Reconstitution: Can happen when someone’s CD4 cell count goes up after they start HIV treatment. Fever, swelling, redness, or discharge may mean that their immune system is getting stronger. But this reaction can be very serious and must be treated accordingly.

Immune Response: When the body defends itself against a foreign invader, such as a virus or bacteria.

Immune System: The group of cells and organs whose job is to protect the body from infections.

Immunocompromised: Someone whose immune system has been weakened so it can no longer protect them from infections.

Immunodeficiency: Inability to produce normal amounts of the disease-fighting cells that protect the body against infections.

Immunosuppression: Inability of the immune system to work as well as it should. May be caused by drugs, including chemotherapy, or by diseases such as HIV infection.

Integrase Inhibitor: A class of HIV drugs that blocks or prevents HIV from putting itself into the DNA of CD4 cells.

Lipodystrophy: A problem with the way the body distributes fat.

Mother-to-Child Transmission (MTCT): The passing of HIV from an infected mother to her infant. The infant may become infected while in the womb, during labor and delivery, or through breastfeeding.

Mutation: A change in a virus that can be passed down to future generations of the virus. This changed virus can then become resistant to different HIV drugs.

Non-Nucleoside Reverse Transcriptase Inhibitor (NNRTI): A class of HIV drug that sticks tightly to a protein that HIV needs to make more copies of itself. Because HIV can’t use the protein, it can’t complete the copying process.

Nucleoside Reverse Transcriptase Inhibitor (NRTI): A class of HIV drug (also known as nukes) that pretends to be something HIV needs to multiply. When HIV uses a nuke, it cannot complete the copying process.

Pill Burden: The number of pills taken in an HIV drug regimen. A high pill burden may cause people to stop taking their medicines as directed.

Protease Inhibitors (PIs): A class of HIV drugs that prevents new copies of HIV from being infectious. PIs inhibit a protein called protease, and without it, HIV can’t make copies of itself.

Resistance: When a person doesn't respond to one or more HIV drugs.

Salvage Therapy: A treatment regimen for people who have had treatment failure with at least two HIV drugs and who have a high level of drug resistance.

Side Effect: When a drug causes a reaction in the body that it is not meant to cause. Usually refers to something unwanted, such as headache, skin irritation, or liver damage.

Standard of Care: A treatment plan that experts agree is the best way to treat a certain disease or condition.

T Cell: A type of white blood cell that fights disease. T cells include CD4 cells and CD8 cells, both important players in the body's immune system.

Tolerability: How well a drug is handled by the body.

Treatment-Experienced: A person with HIV who is currently taking HIV drugs or who has taken HIV drugs in the past.

Treatment Failure: When an HIV treatment stops controlling HIV infection. This can happen when a person isn’t taking the drug as directed, when the HIV strain becomes resistant to treatment, and/or when the drug is causing harm to the body.

Treatment-Naïve: A person with HIV who has never taken HIV drugs.

Treatment Regimen: A plan of treatment, usually with drugs, that is designed to make a person’s health better.

Undetectable Viral Load: When the amount of HIV in the blood is too low to be seen on a viral load test. Getting to undetectable is a good thing, but it does not mean your HIV is cured, and you can still pass it to others.

Viral Load: The amount of HIV found in a blood sample. When viral load goes up or down, your healthcare professional can get an idea of how well treatment is working.