A

AIDS (Acquired Immunodeficiency Syndrome): Is short for "Acquired Immune Deficiency Syndrome." It refers to the late stages of the disease of a person who is infected with the virus called HIV.

Antibodies: An antibody is a type of protein that is produced by your body when a virus or other micro organisms like bacteria enters your body.

Antiretroviral agents: Substances used against retroviruses such as HIV.

C

CD4 cells: A type of white blood cell, one of the components of the immune system that helps the body fight infection. Also known as T-cells, T helper cells, or CD4 lymphocytes. When HIV infects these cells they become the site of HIV replication and are killed as a result of this process and others.

CD4 cell count: A measurement of the strength of your immune system. The higher your CD4 cell count, the stronger your immune system. CD4 cells (also called T-helper cells) are a type of white blood cell. These cells protect your body from germs that can cause infections and diseases.

Cell: The basic unit of all living tissue, composed of a nucleus, cytoplasm, and organelles surrounded by a plasma membrane.

Combination therapy: Two or more drugs or treatments used together to achieve the best results against HIV infection and/or AIDS. Combination therapy may be more effective in decreasing viral load. An example of combination therapy would be the use of two nucleoside analog drugs plus either a protease inhibitor or a non-nucleoside reverse transcriptase inhibitor.

Cryptococcis: An infectious disease that occurs in patients with HIV due to the fungus Cryptococcus neoformans. It can spread from the lungs to the brain, the central nervous system, the skin, the skeletal system, and the urinary tract.

E

ELISA: Enzyme-linked immunosorbent assay, an extremely sensitive test used to screen for HIV.

Enzyme immunoassay (EIA): Test used to measure the amount of antibodies to HIV in the blood.

H

HIV/HIV-1: Stands for "Human Immunodeficiency Virus." HIV is a virus that attacks your immune system, making it hard for your body to fight infections and disease, and eventually causes AIDS.

I

Immune system: Is a network of cell and organs that protect your body from infections and disease.

M

Mycobacterium avium complex (MAC): A common opportunistic infection caused by Mycobacterium avium and Mycobacterium intracellulare, which are two very similar mycobacterial organisms found in soil and dust particles. MAC is a life-threatening disease, although new therapies offer promise for both prevention and treatment. MAC disease is extremely rare in persons who are not infected with HIV.

N

Neuropathy: The name given to a group of disorders involving nerves. Symptoms range from a tingling sensation or numbness in the toes and fingers to paralysis. It is estimated that 35 percent of persons with HIV disease have some form of neuropathy.

Non-nucleoside reverse transcriptase inhibitors (NNRTIs): A class of antiretroviral drugs that block HIV replication by blocking the function of the viral protein reverse transcriptase.

Nucleoside: Part of a nucleotide, which is one of the structures that form chains of DNA and RNA molecules.

Nucleoside analog reverse transcriptase inhibitors (NRTIs): A class of antiretroviral drugs that block HIV replication by blocking the function of the viral protein reverse transcriptase.

 O

Opportunistic infections: Illnesses caused by different organisms, some of which usually do not cause disease in people with a normal immune system. Opportunistic infections of the lungs, brain, eyes, and other organs can develop in people with HIV infection. Opportunistic infections common in people diagnosed with AIDS include Pneumocystis carinii pneumonia; Kaposi's sarcoma; cryptosporidiosis; histoplasmosis; other parasitic, viral, and fungal infections; and some types of cancers.

P

Pancreatitis: Inflammation of the pancreas that can produce severe pain and debilitating illness. Severe pancreatitis can be fatal.

Pneumocystitis carinii pneumonia: An infection of the lungs caused by Pneumocystis carinii The microorganism grows rapidly in the lungs of people with AIDS and is a frequent AIDS-related cause of death. P. carinii infection sometimes occurs in the skin, eyes, spleen, liver, or heart.

Protease inhibitors (PIs): A class of antiretroviral drugs that bind to and block HIV protease to prevent the production of new infectious viral particles.

S

Side effects: Undesirable effects of a drug (or vaccine).

T

Toxoplasmosis: An infection caused by Toxoplasma gondii, a parasite. The parasite is carried by cats, birds, and other animals, and is found in soil contaminated by cat feces and in meat, particularly pork. The parasite can infect the lungs, retina of the eye, heart, pancreas, liver, colon, and testes. If the immune system becomes severely damaged, as in HIV-infected persons, T. gondii can begin to multiply and cause severe disease. In HIV-infected persons, the most common site of toxoplasmosis is the brain.

Thrush: Sore patches in the mouth caused by a fungus called Candida albicans. Thrush is one of the most frequent early symptoms or signs of an immune disorder, such as HIV.

U

Undetectable: A very low level of HIV RNA in the blood, below the level that can register on a viral load test. For a sensitive test, undetectable may be less than 20 copies/mL of HIV RNA, on others it may be just below 400 copies/mL.

V

Viral load: Is a blood test that measures the amount of the HIV in your blood and how active the virus is in your body. Higher numbers mean you have more virus in your body.

Viral load test: Test that measures the quantity of HIV RNA in the blood. Results are expressed as the number of copies per milliliter of blood plasma. Research indicates that viral load is a better predictor of the risk of HIV disease progression than the CD4 count. The lower the viral load the longer the time to AIDS diagnosis and the longer the survival time. Viral load testing for HIV infection is being used to determine when to initiate and/or change therapy.

Virus: A parasitic microorganism that has no independent metabolic activity and must use the capabilities of a cell within a living plant or animal to replicate itself.

W

Western Blot test: A laboratory test for specific antibodies to confirm repeatedly reactive results on the HIV, ELISA or EIA tests. In the US, Western Blot is the validation test used most often for confirmation of these other tests.

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