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From AZT to ZDV, a Glossary for People With HIV

December 1997

A note from The field of medicine is constantly evolving. As a result, parts of this article may be outdated. Please keep this in mind, and be sure to visit other parts of our site for more recent information!

Especially at the beginning, the specialized language of HIV disease can be confusing -- and that confusion can lead to misinterpretation of specific instructions, missed doses of specified drugs, and miscommunication between patients and their care-providers. The best way to prevent such mix-ups is to familiarize yourself with the abbreviations and acronyms, the symbols and shorthand terms, that are commonly used by healthcare professionals who take care of people with HIV.

When your care-provider says, "If your HIV RNA doesn't drop below 500 by the time we run your next labs, I think we'd better consider adding a PI to your d4T and 3TC to boost your CD4s and prevent OIs," that care-provider knows exactly what he or she is saying. Do you? If you aren't absolutely certain what all those letters and numbers mean, you aren't in a position to make fully informed decisions about the care you are receiving. And you should be.

In our very first issue, Dr. Paul Volberding, the Editor-in Chief of AIDS Care, observed that "successful long-term care of people with HIV infection requires full cooperation and open communication, conscientiousness and compassion -- on all sides." That sort of cooperation -- and that level of communication -- are only possible when everyone involved in the process is speaking the same language.

To help you become a full partner in that process, the editors of AIDS Care have developed this clear, concise, alphabetical list of all the names, terms, and acronyms you need to know in order to speak the specialized language of HIV. It's a fairly long list, but our decision was to err on the side of inclusion -- so that this Pull Out and Save glossary will be the only one you need to consult.


A | B | C | D | E | F | G | H | I | J | K

L | M | N | O | P | R | S | T | V | Z


Accelerated Approval: The process by which the FDA (Food and Drug Administration) rapidly approves experimental drugs for the treatment of life-threatening conditions.

Acemannan: Ingredient in aloe-vera juice that has shown anti-HIV activity in the test tube.

Acidophilus: Bacteria that, when ingested, helps restore the normal bacterial populations in the human digestive system. Found in yogurt, it may be helpful in preventing thrush.

ACTG: The AIDS Clinical Trials Group is a network of federally-funded institutions that conducts AIDS research. It is coordinated by the National Institutes of Allergy and Infectious Disease (NIAID).

Acute: Rapid and recent onset, usually involving intense symptoms.

Acyclovir (Zovirax®): A drug used to treat herpes infections (herpes simplex and herpes zoster, or shingles).

ADC: see "AIDS Dementia Complex."

Adherence: The extent to which a patient takes his/her medications according to the prescribed schedule (also called "compliance").

Adverse Event: An unwanted side effect of a drug; toxicity (see "Side Effect").

AIDS (Acquired Immunodeficiency Syndrome): A state of severe immune suppression brought about by infection with HIV. A diagnosis of AIDS is given to a person with HIV infection who experiences at least one condition from a list compiled by the Centers for Disease Control and Prevention; the condition may be an opportunistic infection like CMV or a cancer like Kaposi's sarcoma. In addition, anyone with HIV infection and a CD4 count less than 200 is given a diagnosis of AIDS.

AIDS Dementia Complex (ADC): Disturbance in brain function that is thought to be due to HIV infection in the brain. ADC may impair a person's ability to function in social or work settings.

AIDS-Related Complex: see "ARC."

Albendazole: A treatment approved for parasitic infections that has shown activity against microsporidiosis; may cause liver toxicity and low white-cell counts.

Alopecia: Hair loss.

Alpha Interferon: A natural substance produced by white blood cells in response to viral infections, alpha interferon is now manufactured in the lab and used to treat Kaposi's sarcoma as well as other illnesses; other interferons (beta and gamma) are being studied.

Alternative Medicine: This phrase describes medical approaches that differ from Western, drug-based medicine. It includes Chinese medicine, Ayurveda, acupuncture, and homeopathy, among other treatments.

Amoebas: Parasites that invade the gastrointestinal tract, causing diarrhea, bloating, and abdominal pain.

Amphotericin-B (Fungizone®): A drug used to treat serious fungal infections. It is given intravenously (IV), but an oral version is now available for difficult-to-treat oral thrush. Side effects of IV amphotericin include kidney damage and low white-cell counts as well as nausea, vomiting, chills, and fevers.

Anaphylaxis: A severe allergic reaction, usually to a drug. Symptoms include difficulty breathing, low blood pressure, and rash, sometimes with blisters or hives. Persons experiencing anaphylaxis require immediate medical attention (injection with epinephrine) as this condition is potentially life-threatening.

Anemia: A condition in which the blood is not able to deliver enough oxygen to the tissues. Anemia may be caused by too few red blood cells, impaired red blood cells, or insufficient/ineffective hemoglobin.

Anergic: Term used to describe the inability of the immune system to mount a response against particles or substances that usually cause a reaction.

Anorexia: Loss of appetite; weight loss related to loss of appetite.

Antibiotic: A drug that slows bacterial growth or kills bacteria.

Antibody: A natural substance made by B cells (which are a type of white blood cell) that is specifically designed to neutralize an invading organism. HIV has a much smaller effect on the body's ability to produce antibodies compared to its other effects on the immune system.

Antigen: A portion of a foreign substance or organism against which an antibody is designed by B cells. Antigens are neutralized by antibodies.

Antiretrovirals: A class of drugs that inhibit retroviruses like HIV.

Aphasia: Partial or complete loss of the ability to speak, or to understand spoken language.

Aphthous Ulcer: Very painful sore in the mouth or throat: treated with steroids or thalidomide.

ARC (AIDS-Related Complex): This is an old term that is used to describe a collection of symptoms in a person with HIV who does not have a diagnosis of AIDS. The term is rarely used today.

Arm: All of the study subjects taking a particular drug or drug dose are said to be in that "arm" (or "cohort") of the study.

Asymptomatic: Without symptoms; clinically normal.

Ataxia: Loss of motor coordination.

Atavoquone (Mepron®): A drug used to treat PCP and, sometimes, toxoplasmosis.

Atrophy: Tissue wasting; loss of body mass.

Azithromycin (Zithromax®): An antibiotic used to treat Mycobacterium avium complex (MAC).

AZT (Retrovir®, zidovudine, ZDV): The first drug licensed to treat HIV. Today it is almost always used in combination with other anti-HIV drugs. Side effects include nausea, vomiting, and low red or white blood cell counts. Also used to prevent transmission of HIV from mother to fetus.


Bacteremia: Presence of bacteria in the bloodstream.

Bactrim® (TMP/SMX): An antibiotic used to prevent and treat PCP as well as many other infections.

B Cell: A type of white blood cell that produces antibodies.

Biaxin®: see "Clarithromycin."

B.I.D.: Latin abbreviation meaning twice a day; refers to how often pills are to be taken.

Bioavailability: The extent to which a drug taken by mouth is absorbed into the bloodstream.

Biopsy: Removal of a piece of tissue for examination under the microscope, for diagnostic purposes.

Blinded: Participants do not know which arm of a clinical study they are in (i.e. they do not know what drug or drug dose they are getting).

Blood-Brain Barrier: A tight network of cells lining the vessels of the brain that makes it difficult for drugs to get into brain tissue.

Bronchitis: Infection of the airways (bronchi) leading to the lungs.

Bronchoscopy: A diagnostic procedure that involves passing a flexible tube with a camera attached into the airways.

Buyers' Club: An organization that assists Americans who want to purchase drugs or other products that are not available or licensed in this country; only small quantities for personal use can be purchased in this manner.


Cachexia: Severe wasting/weight loss.

Cancer: Unregulated cell growth that invades normal body structures.

Candida: A yeast-like organism that causes infection of the mucous membranes (mouth, gastrointestinal tract, vagina). Symptoms include white patches on the affected areas ("thrush"), pain, and itching. The condition of having a candida infection is called "candidiasis." Several treatments are available.

Candidiasis: see entry above.

Carbohydrate: A nutritional molecule that consists of carbon, oxygen, and hydrogen atoms. Carbohydrates include sugars and starches.

Catheter: A tube that allows access to the bloodstream and is left in place for an extended period of time. Catheters are also used for other purposes, such as draining the bladder.

CDC: see "Centers for Disease Control and Prevention."

CD8 Cell: A subtype of T lymphocytes that has traditionally been seen as a "suppressor" cell, one that shuts off the immune system when an invading organism is eliminated. CD8 cells also perform active immunity functions, such as killing certain infected cells.

CD4 Cell: Also known as "T4" or "helper T cell," the CD4 cell is the primary target of HIV. It performs critical functions such as signaling other parts of the immune system to respond to an infection. Treatment decisions are often based on CD4 count. Normal counts range from 500 to 1500.

CD4 Percent: The percent of all lymphocytes (including B cells, CD4 cells, and CD8 cells) that are CD4 cells. The normal value is 35% to 40%.

CD4/CD8 Ratio: This number is a reflection of the health of the immune system. The normal ratio is two-to-one (i.e. twice as many CD4 cells as CD8 cells).

Cell-Mediated Immunity (CMI): This term simply refers to the parts of immune function that are carried out by the body's CD4 and CD8 cells (as opposed to "humoral" immunity).

Centers for Disease Control and Prevention (CDC): This federal agency is concerned with control of infectious diseases, such as HIV, in the U.S.

Central Nervous System (CNS): The part of the nervous system that consists of the brain and spinal cord, as opposed to the peripheral nerves that supply the tissues of the body.

Cerebrospinal Fluid (CSF): Fluid produced by the CNS that protects the brain and spinal cord. When a spinal tap is done, CSF is removed for diagnostic purposes.

Cervical Dysplasia: Abnormal cells from the cervix that may indicate a pre-cancerous condition.

Cervix: The lower end of the uterus that protrudes into the vagina.

Chemotherapy: Use of chemicals to treat a disease; commonly used to refer to cancer treatments.

Chlamydia: A sexually-transmitted disease caused by an organism called Chlamydia trachomatis; easily treated with antibiotics.

Chronic: Long-term symptoms or diseases that often require on-going suppressive treatment.

Cidofovir: A recently-approved drug to treat CMV retinitis. Most severe side effect is kidney damage; must be given with intravenous hydration and probenecid.

Clarithromycin (Biaxin®): An antibiotic that is used to treat Mycobacterium avium complex (MAC).

Cleocin®: see following entry.

Clindamycin (Cleocin®): An antibiotic that is used as an alternative treatment for PCP and toxoplasmosis. Commonly causes diarrhea and may cause growth of an organism called Clostridium difficile.

Clinical Trial: An experimental study in people to test the safety and efficacy of new drugs.

Clotrimazole (Lotrimin®, Mycelex®): A medication used to treat fungal infections of the mouth and vagina; used orally or applied directly to the affected area.

CMV (Cytomegalovirus): A virus that is a member of the herpesvirus family and is present as a silent infection in most people. CMV often becomes re-activated in people with advanced immunosuppression (CD4 counts under 50) and can cause disease in many parts of the body, especially the eye, throat, and colon. Several treatments are available.

CNS: see "Central Nervous System."

Colitis: Inflammation of the colon.

Colposcopy: A diagnostic procedure to closely examine the cervix, involving use of a microscope. This is an accurate test to examine the cervix for abnormal cell growth.

Combination Therapy: Use of more than one drug to treat a disease or infection.

Complementary Medicine: This usually refers to treatment approaches other than traditional Western modalities. Synonymous with "Alternative Medicine."

Complete Blood Count (CBC): This is a lab test that reports the number of white blood cells, red blood cells, platelets, hemoglobin, and hematocrit as well as other values that reflect the overall health of blood.

Compliance: The extent to which a patient takes medications according to the prescribed schedule; synonymous with "adherence."

Condyloma Acuminata: Genital warts, caused by a virus called human papillomavirus (HPV). Usually treated by destruction of the wart using various means (electricity, acids, liquid nitrogen).

Contraindication: A situation that prevents use of a certain medication (for instance, using two drugs that have the same toxicity).

Control group: Clinical trial participants who do not receive the experimental treatment.

Corticosteroid: A hormone that is produced in the outer part of the adrenal gland, known as the cortex. Corticosteroids are synthetically produced and used to treat many conditions; common ones include prednisone, decadron, and hydrocortisone.

Crixivan®: see "Indinavir."

Crossover: A clinical trial in which the experimental and control groups switch treatments.

Cross-Resistance: This refers to the development of resistance by a viral strain that makes it less susceptible to other medications in the same class.

Cryptococcal Meningitis: A fungal infection of the membranes lining the central nervous system. These membranes are called "meninges." Diagnosis requires a spinal tap. Common symptoms are headache, fever, sensitivity to light, confusion, and blurry vision.

Cryptosporidiosis: A parasitic infection of the intestines that is associated with severe, chronic, non-bloody diarrhea. There are no standard treatments, but a number of medications are used experimentally.

CSF: see "Cerebrospinal Fluid."

Culture: A diagnostic procedure in which a sample of body fluid or tissue is exposed to conditions that would favor growth of an infecting organism.

Cytokine: A chemical messenger produced by white blood cells that helps carry out immune functions.

Cytomegalovirus: see "CMV."

Cytovene®: see "Ganciclovir."


Dapsone: A drug used as an alternative medication for the prevention of PCP and toxoplasmosis. May cause destruction of red blood cells. Patients who are taking ddI and dapsone need to follow specific regimens to avoid unwanted interactions between these drugs.

Data Safety Monitoring Board (DSMB): A group of independent researchers who review the data while a clinical trial is going on, to determine if one drug is markedly safer or more effective than another.

ddC (Hivid®, zalcitabine): A drug that inhibits an enzyme used by HIV called "reverse transcriptase." Side effects include pancreatitis and peripheral neuropathy. This drug is almost never used alone.

ddI (Videx®, didanosine): A drug that inhibits an enzyme used by HIV called "reverse transcriptase." Side effects include pancreatitis, peripheral neuropathy, and diarrhea.

Deca Durabolin®: see "Nandralone Decanoate."

Delavirdine (Rescriptor®): A drug that inhibits an enzyme used by HIV called "reverse transcriptase," via a different mechanism than AZT and related drugs. Side effects include temporary skin rash.

Dementia: see "AIDS Dementia Complex (ADC)."

Depression: A state characterized by depressed mood, decreased energy, reduced interest in sex, suppressed appetite, and too much sleep or sleeplessness. Depression is common in people with HIV infection; it often responds well to treatment.

Dermatitis: Inflammation of the skin, which can be due to many causes, including unknown ones.

Desensitization: Process by which a person who has a history of allergic reaction to a drug has it slowly introduced into their bloodstream over time in such a way that the reaction does not occur.

d4T (Zerit®, stavudine): A drug that inhibits an enzyme used by HIV called "reverse transcriptase." The most common side effect is peripheral neuropathy.

DHEA (dihydroepiandosterone): Produced by the adrenal glands, this hormone's functions remain unclear. Some people with HIV infection believe that they derive benefit from taking DHEA, but its effects are unproven so far. It is available over the counter.

Didanosine: see "ddI."

Diflucan®: see "Fluconazole."

Dihydroepiandosterone: see "DHEA."

Double-Blinded: Neither the clinical trial participants nor the researchers know who is receiving which drug or drug dose.

Dyspepsia: Stomach or intestinal upset, including nausea, increased gas, and vomiting.

Dysphagia: Difficulty swallowing.

Dysplasia: Abnormal tissue growth.

Dyspnea: Shortness of breath or other difficulty in breathing.


EBV: see "Epstein-Barr Virus."

Echinacea: An herb used by many people with HIV infection, which is thought to combat weight loss, although there is no hard evidence of this effect to date.

Edema: Tissue swelling, usually in the extremities; it results from collection of fluid in the tissue.

Efficacy: The power of the drug or treatment to accomplish its intended goals; how well it works.

Encephalitis: Inflammation of the brain; can be due to many causes.

Enzyme: A molecule made by cells that allows the body to speed up chemical reactions.

Eosinophilic Folliculitis: A bothersome skin condition, involving inflammation of the hair follicles (the base of the hair that is underneath the skin). The exact cause is unknown, but researchers have determined that a certain type of white blood cell is responsible for the inflammation. A number of treatment approaches are used, such as exposure to ultraviolet light, use of antihistamines, and topical steroids.

Epivir®: see "3TC."

Epogen®: see "Erythropoietin."

Epstein-Barr Virus (EBV): A member of the herpesvirus family, EBV has been implicated in mononucleosis, certain kinds of lymphoma, and oral hairy leukoplakia. Acyclovir, which is active against other herpesviruses, has little effect against EBV.

Erythropoietin (Epogen®): This is a hormone made by the kidneys that stimulates red blood cell production in the bone marrow. Synthetic versions are available by prescription to treat certain kinds of anemia, such as the anemia caused by AZT.

Erythrocytes: Red blood cells.

Exclusion Criteria: Reasons why some prospective participants should not be included in a clinical study (e.g. a trial may not want people with CD4 counts above 500, or pregnant women, or patients who have previously used the drug being studied).

Expanded Access: The FDA allows early use of some unapproved medications for people in life-threatening situations. A number of programs are in place to ensure "expanded access" such as Compassionate Use, Parallel Track, and Treatment-IND programs.

Experimental Group: Clinical trial participants who do receive the experimental treatment.


Famvir®: see entry below.

Famciclovir (Famvir®): An alternative treatment for herpes simplex (oral and genital herpes) and herpes zoster (shingles).

Floaters: Spots or other forms that drift across the field of vision; may be a symptom of CMV retinitis.

Fluconazole (Diflucan®): An antifungal drug used to treat thrush ("candidiasis"), cryptococcal meningitis, and other fungal infections.

Fortovase®: see "Saquinavir."

Foscarnet (Foscavir®): A treatment for CMV infections; possible side effects include kidney toxicity, nausea, and anemia.

Foscavir®: see entry above.

Fungizone®: see "Amphotericin-B."

Fungus: A type of infection caused by yeasts and molds. Common fungal infections in people with HIV infection include candida (thrush), cryptococcus, aspergillus, and histoplasma.


Ganciclovir (Cytovene®): An antiviral drug used to treat CMV infections. Common side effects include low white blood cell counts (neutropenia) and low platelet counts (thrombocytopenia).

G-CSF (Neupogen®): A naturally-occurring substance that stimulates production of neutrophils. G-CSF is now made in the lab and is particularly useful when given with treatments that are toxic to neutrophils (e.g. ganciclovir and certain anti-tumor agents).

GM-CSF (Leukine®, Prokine®): Similar to G-CSF, except that, in addition to stimulating neutrophils, GM-CSF stimulates production of macrophages, another type of white blood cell.

Gonorrhea: A sexually-transmitted disease that affects the genitals of both sexes, gonorrhea causes burning or difficulty with urination, itching, and a yellow or green discharge. It is easily treated with antibiotics.


HAART (Highly-Active Anti-Retroviral Therapy): Combination anti-HIV therapy, usually involving a protease inhibitor. Combinations of drugs have been found to be highly suppressive of HIV, and this strategy helps delay or avoid the development of treatment-resistant viral mutants.

Half-Life: The time it takes for half of a drug dose to be eliminated from the bloodstream (or to be inactivated).

Hematocrit: This is the percentage of blood that is taken up by red blood cells. Normal values for men are 45% to 55%; for women, the normal range is 37% to 47%.

Hemoglobin: The molecule in red blood cells that carries oxygen; normal values for men are 13 to 17 grams; for women, the normal range is 12 to 16 grams.

Hemorrhage: Loss of a large quantity of blood, either internally or externally.

Heparin: A drug that decreases the blood's ability to clot.

Hepatitis: Inflammation of the liver, which can be caused by an infection, a chemical such as alcohol, or other causes. Hepatitis A is caused by a virus that is transmitted by food or sex; hepatitis B is caused by a virus transmitted by sex or blood exposure (e.g. needle-stick injury); hepatitis C is caused by a virus that is thought to be transmitted by blood products. There are vaccines for hepatitis A and B.

Herpesvirus: A family of viruses that includes herpes simplex one and two (HSV-1, HSV-2), cytomegalovirus (CMV), Epstein-Barr Virus (EBV), Varicella Zoster Virus (VZV) and other subtypes called Human Herpes Viruses (HHV-1, HHV-2, etc.). Some of these viruses are thought to accelerate the progression of HIV infection.

Herpes Zoster: see "Shingles."

Hickman Catheter: A surgically-implanted line that allows access to a major vein. It can be left in place for long periods. The advantage to these catheters is that people who require frequent intravenous treatments do not need to be stuck with a needle each time. The major disadvantages are that they are cosmetically undesirable and they can become infected.

Histoplasmosis: A fungal infection that can cause problems in the lungs, on the skin, and other sites. It is most prevalent in the Southwestern U.S., but people can have it in any part of the country.

HIV-1 (Human Immunodeficiency Virus): The causative agent of AIDS. Infection with HIV does not mean that a person has AIDS; see "AIDS" for more information. It is the predominant virus causing AIDS in the U.S. and Europe.

HIV-2: Also a virus that causes AIDS, although it may be somewhat less potent than HIV-1. It is the predominant virus causing AIDS in Western Africa.

Hivid®: see "ddC."

HPV (Human Papillomavirus): Causative agent of warts, anywhere on the body. More than a hundred subtypes have been identified. Certain subtypes are associated with cervical cancer.

Human Growth Hormone: A chemical messenger in the body that stimulates tissue growth. A synthetic version is available by prescription for children with growth retardation and persons with significant wasting (weight loss).

Human Immunodeficiency Virus: see "HIV-1" and "HIV-2."

Human Papillomavirus: see "HPV."

Hypericin (St. John's Wort): A compound derived from an herb that may have anti-HIV activity. It is widely used as a natural treatment for depression. The main side effect is increased sensitivity to sunlight.

Hyperthermia: An experimental treatment that involves heating the blood after removing it from the body, in an attempt to kill HIV. This is a dangerous and, so far, ineffective treatment.


Idiopathic Thrombocytopenic Purpura: see "ITP."

Immune System: The network of white blood cells and the chemical products they produce to protect the body from foreign "invaders." One major division is between the "cellular" portion, which involves T cells, and the "humoral" portion, which involves B cells that make antibodies. The two parts work hand-in-hand.

Invirase®: see "Saquinavir."

ITP (Idiopathic Thrombocytopenic Purpura): A process that results in destruction of platelets by an unknown mechanism. ITP can lead to easy bruising and, if severe, uncontrolled bleeding. Treatments include AZT and immunoglobulin.

Immunization: Use of a vaccine to stimulate the immune system to ward off particular infections (flu, measles, typhoid, etc.).

Immunocompromised, Immunosuppressed: The state of having a damaged immune system and, therefore, increased susceptibility to illness.

Immunoglobulin: A substance made by B cells that neutralizes specific disease-causing substances and organisms; also known as an "antibody."

Inclusion Criteria: List of things (clinical state, blood values, etc.) that are required of every participant in a clinical trial at time of entry.

Indication: Intended purpose for a drug or treatment, as determined by the FDA.

Indinavir (Crixivan®): A protease inhibitor that must be taken three times a day on an empty stomach to aid absorption. May cause kidney stones and increased triglyceride levels.

Inflammation: An immune reaction characterized by redness, pain, heat, swelling, and sometimes, loss of function.

Informed Consent: The process by which a healthcare provider gives a patient information, including pros and cons, about a potential new treatment; when a person is entering a clinical trial, that person must sign a document with this information, thereby providing "informed consent."

INH: see "Isoniazid."

Interferon: see "Alpha Interferon."

Interleukin: A chemical messenger made naturally by cells; many subtypes have been discovered that turn on and off certain aspects of immunity. Synthetic versions of interleukins are being tested as treatments that might boost the immune system.

In Vitro: Latin for "in glass"; refers to test-tube studies, such as mixing HIV with a potential antiviral to see if the drug inhibits the virus.

In Vivo: Latin for "in living [organisms]"; refers to studies involving people or animals. "In vivo" is a broader term than "clinical trial," which only includes studies in people, not animals.

Isoniazid (INH): A drug used as part of a combination to treat TB. INH is also used alone to prevent TB in people who have been exposed. The chief toxic effect involves the liver, so people on this drug need to have their liver enzymes checked periodically.

Itraconazole (Sporanox®): An antifungal drug used to treat fungal infections of the nails, histoplasmosis, and other fungal infections. It is also used for candida (thrush) that is resistant to standard treatments. Side effects include GI problems, rash, and headache.


Jaundice: A yellowish tone to the skin or the whites of the eyes. Jaundice is caused by bilirubin, a breakdown product of hemoglobin, a molecule found in red blood cells. There are several reasons why bilirubin can be elevated in the bloodstream; classic causes include liver disease, gall bladder disease, use of certain drugs, and increased destruction of red blood cells.


Kaposi's Sarcoma (KS): A tumor that is probably caused by a virus, KS typically appears as a flat or raised purplish patch on the skin or mucous membranes (in the mouth, rectum, or vagina). KS areas on the skin are usually not painful. Its appearance may be very subtle in dark-skinned people. KS may also spread to internal organs, like the esophagus, intestines, colon, or lungs. Several treatments are available, including chemotherapeutic agents injected into skin lesions as well as intravenous or intramuscular injections. Radiation is also used, and many experimental treatments are being studied.

Karnofsky Index: A scale used to assess how well someone functions. It is not specific to AIDS. A score of 100 is given to a fully and normally functioning person. Scores decrease by 10; a score of 30 indicates that a person needs to be hospitalized.

Ketoconazole (Nizoral®): An antifungal that is used for candidiasis (thrush). It is available as a pill, cream, or liquid. The most serious side effect is liver damage.


Lamivudine: see "3TC."

Latency: A period of little or no activity. In the HIV world, latency usually refers to a stretch of time during which the virus is quiet and not reproducing. However, even when people have no symptoms, their virus may be very active. The best way to judge if you are in a period of latency is to have a "viral load" test.

Lesion: A broad term used to describe any abnormality in or on the body. Scratches, bumps, wounds, scars, tumors, insect bites, rashes, and flat patches are all called lesions. Abnormalities of internal organs are often called lesions.

Leukine®: see "GM-CSF."

Long-Term Non-Progression: This phrase came into vogue in the late 1980s, when it became clear that some people with HIV infection did not develop progressive disease. It is non-specific, and it includes people who have responded very well to treatment, people who have mounted an effective, long-term immunologic response to HIV, and people who have a weak, non-disease-producing strain of the virus. There is no strict definition, but it usually implies that an individual has had HIV infection for a decade or longer and is clinically well, with normal or near-normal CD4 counts.

Lotrimin®: see "Clotrimazole."

Lumbar Puncture (LP): A spinal tap; the doctor inserts a needle in a space between the bones that form your spinal column (vertebrae) in order to obtain cerbrospinal fluid. If meningitis is suspected, an LP is usually required.

Lymph: This is the fluid that fills your lymphatic vessels and runs through lymph nodes. Eventually, lymph is circulated into the bloodstream, although the lymphoid system is separate from the vessels that carry blood. Lymph contains lots of white blood cells. The lymphoid system plays a major role in the immune reaction to infections. HIV is very active in the lymphoid system, especially lymph nodes.

Lymph Node: An outpocketing of the lymphoid system where immune reactions occur. They range in size from peas to kidney beans. Collections of lymph nodes are found in the neck, around the collarbone, in the armpit (the "axilla"), and in the groin. During a physical exam, doctors usually feel these places, looking for swollen lymph nodes, which are a sign that active infection is present.

Lymphocyte: Another term for a type of white blood cell; it is a broad category that includes B lymphocytes and T lymphocytes. T lymphocytes are further divided into T4 (see "CD4") and T8 (see "CD8").

Lymphoma: A cancer of the lymph nodes. Two major varieties are Hodgkin's and non-Hodgkin's lymphoma. The incidence of lymphomas is increased in people with HIV infection compared to the general population. They can occur at high CD4 counts, but are more common in people with low counts. Common symptoms are swollen lymph nodes, weight loss, fevers, and malaise. Treatment is with radiation and/or chemotherapy.


MAC (Mycobacterium avium complex): Caused by one of a variety of organisms called mycobacteria (which are different from bacteria), this is an infection that is difficult to treat. However, more effective treatments have become available in the last few years. A combination of drugs, including several used to treat TB, is employed. Symptoms include weight loss, low-grade fevers that have a predictable daily pattern, night sweats, and general malaise. MAC is uncommon in people with CD4 counts above 50. The risk of MAC is great enough that doctors routinely prescribe medication to prevent it in people with low CD4 counts.

Macrophage: A "scavenger" white blood cell that engulfs anything recognized as "non-self" (debris, particles, viruses, bacteria, etc.) and destroys it. Macrophages, like CD4 cells, are susceptible to HIV infection.

MAI: Another name for "MAC."

Maintenance Therapy: This refers to long-term (perhaps life-long) treatment of an infection, to make sure it does not come back. Usually, drug doses are lower than the levels used to treat an actual case of the infection. Examples of infections that require maintenance (or "suppressive") therapy include PCP, MAC, CMV, and TB.

Malaise: Feeling lousy, low, generally unwell.

Malignant: Often used to describe cancers, this term implies aggressive invasion, to the point where surrounding structures are compromised or destroyed. Alternatively, a tumor that begins in one spot and spreads to a distant site is described as malignant. More generally, a disease process other than a tumor may be described as malignant, meaning that it is rapidly progressive and destructive.

MDR-TB (Multidrug-Resistant TB): A form of tuberculosis (TB) that is resistant to most standard treatments. As the name implies, this is a very difficult disease to treat and requires combinations of anti-TB drugs. Sometimes, experimental agents must be used. MDR-TB develops when patients with TB do not take all of the drugs prescribed for as long as they are supposed to.

Meningitis: Infection of the membranes that surround the brain and spinal cord. These membranes are referred to as the "meninges." It is a serious infection and can be due to bacteria, viruses, or fungi. Diagnosis requires a spinal tap (see "Lumbar Puncture"). Lumbar puncture is critical to identifying the cause of infection so that appropriate treatment can be started. Symptoms include a horrible headache, fever, malaise, confusion, and pain when moving the neck. Several treatments are available, depending on what is causing the infection.

Mepron®: see "Atavoquone."

Microsporidiosis: This is an infection of the intestines caused by a parasite. It causes chronic, massive, watery diarrhea. It is difficult to diagnose and treat, but agents are available.

Molluscum Contagiosum: Caused by a virus, this skin infection produces small, pearly-white bumps, usually on the face and torso. The bumps often have a little indentation in the middle. They are not painful or itchy. The only effective treatment, is to destroy the lesions by scooping them out, freezing them with liquid nitrogen, or zapping them with a tiny electric needle. It is important to treat them as early as possible, because they usually get worse and spread. Typically, more than one session is needed to get rid of all of them.

Multidrug-Resistant TB: see "MDR-TB."

Myalgia: Muscle pain.

Mycelex®: see "Clotrimazole."

Mycobacterium avium complex: see "MAC."

Mycosis: A general term for fungal infection.


Nandralone Decanoate (Deca Durabolin®): A male steroid hormone that is being used to treat wasting; given by injection into muscle.

Nelfinavir (Viracept®): A protease inhibitor that is taken three times daily, with food; approved for children and adults. Most common side effect is diarrhea.

Neoplasia: A new tissue growth which is abnormal; usually benign, but may be pre-cancerous.

Nephrolothiasis: Kidney stones.

Neupogen®: see "G-CSF."

Neuropathy: Damage to the peripheral nerves; usually manifests as pain, tingling, or numbness in the feet or, more rarely, the hands. Drugs or HIV itself may cause neuropathy. Many treatments are used for this condition.

Neutropenia: Abnormally low count of a type of white blood cell called "neutrophils." Neutrophils are particularly important in fighting bacterial and fungal infections. There is an injectable drug called Neupogen® that can boost neutrophil counts.

Neutrophil: see entry above.

Nevirapine (Viramune®): A drug that inhibits an enzyme used by HIV called "reverse transcriptase." Nevirapine belongs to a class of drugs called NNRTIs (see entry below). Side effects may include fever, rash, and increased liver enzymes.

Nizoral®: see "Ketoconazole."

NNRTI (Non-Nucleoside Reverse-Transcriptase Inhibitor): A class of drugs that inhibit an enzyme used by HIV called "reverse transcriptase." NNRTIs work by a different mechanism than AZT and similar drugs, which also attack reverse transcriptase. NNRTIs are more specifically targeted to HIV than AZT, etc., so they have fewer side effects. However, resistance develops more quickly with these drugs; to discourage resistance, NNRTIs are always used in combination with other anti-HIV drugs.

Non-Hodgkin's Lymphoma (NHL): A cancer characterized by uncontrolled proliferation of lymphocytes (usually B cells, but sometimes T cells), NHL can cause tumors in lymph nodes or other organs, such as the spleen, bone marrow, gastrointestinal tract, and brain. It is more likely than Hodgkin's lymphoma to cause disease in sites that are distant from one another. There are several grades of NHL. Treatment is with chemotherapy, radiation, or bone-marrow transplant.

Non-Nucleoside Reverse-Transcriptase Inhibitor: see "NNRTI."

Norvir®: see "Ritonavir."

Nucleoside Analog: This is a class of drugs that fight HIV by interfering with the virus's ability to make a key enzyme called "reverse transcriptase." AZT was the first nucleoside analog licensed, and it has been followed by many others, such as ddI, ddC, d4T, and 3TC. These drugs act at the DNA level. They also affect normal cell growth, such as bone marrow cells, so there can be significant toxic effects.


Off-Label: The use of a drug for a purpose not originally allowed by the FDA when the drug was licensed. An example is use of dapsone to prevent PCP (it is licensed to treat leprosy.) The "label" refers to a sheet of instructions included with drugs that is also called the "package insert." It is legal for physicians to prescribe drugs for off-label uses, but insurance companies may not reimburse a patient for the drug in such circumstances.

OHL: see "Oral Hairy Leukoplakia."

OI: see entry below.

Open-Label: A clinical trial in which everyone gets the experimental treatment.

Opportunistic Infection (OI): Many organisms (viruses, bacteria, fungi, etc.) are held in check by the immune system. They often "colonize" the body (i.e. they are present but not noticed) without causing disease. When someone becomes immunocompromised for any reason (HIV infection, cancer, or treatment with immunosuppressive drugs, such as certain kinds of chemotherapy), some of these organisms take advantage of the "opportunity" by growing out of control and causing disease. Common OIs in patients with AIDS include PCP, CMV, MAC, and toxoplasmosis.

Oral Hairy Leukoplakia (OHL): An infection that causes white patches on the sides of the tongue. It is most likely caused by Epstein-Barr virus.


Pancreatitis: Inflammation of the pancreas from any cause. Usual symptoms are abdominal pain, nausea, vomiting, and intolerance of fatty foods. Pancreatic enzymes (amylase, lipase) are elevated. Anti-HIV drugs associated with pancreatitis include ddI and ddC.

Papillomavirus (HPV): A virus that causes warts on many parts of the body; there are more than one hundred strains of HPV and a few are associated with cancer.

Pathogen: Anything capable of causing disease; usually a pathogen is a bug, like a virus or bacteria, but it also refers to substances, like asbestos.

PCP (Pneumocystis carinii Pneumonia): This pneumonia is caused by an organism that most people have in their lungs. The immune system normally prevents the organism from causing disease, but PCP becomes a problem when T cells are below 200. PCP can be prevented in most people by starting medication when T cells are low. The first line of treatment is Bactrim® or Septra® (the same drug with different names). It is essential that people with low counts regularly take medication to prevent PCP, even if they feel perfectly well; the chances of getting PCP are high in the absence of preventive medicine. Symptoms of PCP include low-grade fever, cough (without bringing up phlegm), fatigue, and shortness of breath (for example, when walking up stairs.) If you have these symptoms and your T cells are below 300, go to an emergency room.

PCR (Polymerase Chain Reaction): This is a laboratory test that works at the genetic level. With PCR, tiny amounts of DNA are found and amplified millions of times; it is a test that allows researchers to find a needle in a haystack. PCR is also used to judge how much virus is present in a given blood sample. Viral-load measurements are done with PCR techniques.

PID (Pelvic Inflammatory Disease): A nonspecific infection of the female genital tract, PID may be caused by one or multiple organisms. Symptoms include fever, pain, and vaginal discharge. It is important that PID be treated as soon as possible; it is associated with infertility (inability to get pregnant).

Pentamidine (Pentam®, Nebupent®): A drug used to treat and prevent PCP. Side effects when given by vein include kidney and pancreas damage as well as low blood sugar. Pentamidine can also be inhaled through a special machine to prevent PCP, although this is not a first-line therapy.

Peripheral Neuropathy: Damage to nerves outside of the central nervous system; neuropathy commonly affects the feet, although the hands can be involved as well. Symptoms include tingling and pain in the extremities, as well as numbness. Usually, both sides are affected. Neuropathy can be caused by HIV itself, or by drugs such as ddC.

Peripherally Inserted Central Catheter: see entry below.

Pharmacokinetics: The study of how the body metabolizes a drug, which tissues the drug penetrates, its half-life, and other variables.

PICC Line (Peripherally Inserted Central Catheter): A piece of tubing that is inserted into a vein in the arm, to allow easy delivery of medication without frequent needle sticks. PICC lines can be left in place for up to three months. It must be remembered that they are a potential source of infection.

Placebo: A "look-alike" dummy pill that does not contain drug; placebos are often used in clinical trials.

Platelet: Also called a thrombocyte. A fragment of a larger type of blood cell that helps promote clotting. Normal values are 100,000 to 300,000; when counts drop below 10,000, bleeding becomes a serious concern.

PML (Progressive Multifocal Leukoencephalopathy): An infection of the brain that is caused by a virus; symptoms of PML include difficulty in speaking or in understanding language, unusual movements, or loss of ability to move an extremity, as well as defects in vision.

Pneumocystis carinii Pneumonia: see "PCP."

PPD (Purified Protein Derivative): A test for exposure to TB; a small piece of the bug that causes TB is injected into the skin. There is no way that the test can cause TB. People who have been exposed to TB develop a reaction at the site of injection. People with HIV may have a false negative result (meaning that the test is negative, but they were exposed to TB). HIV patients with positive PPD tests need to take medication to prevent TB, even though they feel well.

Progressive Multifocal Leukoencephalopathy: see "PML."

Prokine®: see "GM-CSF."

Protocol: The overall design, or blueprint, of a clinical study.

PRN: A Latin term used in medicine, meaning that treatment should be given "as necessary."

Prophylaxis: Preventive therapy; "primary prophylaxis" is given to at-risk individuals to prevent a first infection by, say, PCP; "secondary prophylaxis" is given to prevent recurrent infections.

Protease: An enzyme used by HIV to process new copies of virus after it has reproduced; drugs specifically aimed at this enzyme are called "protease inhibitors." Human cells also use protease enzymes, but they are different from the HIV protease.

Pruritic: Itchy.

Purified Protein Derivative: see "PPD."


Randomized: Distributed by chance.

Regimen: Refers to the specific doses and the specified times to take medications.

Remission: Time during which a disease is inactive.

Renal: Related to the kidney.

Rescriptor®: see "Delavirdine."

Resistance: Ability of an organism, such as HIV, to overcome the inhibitory effects of a drug, such as AZT or a protease inhibitor. Resistance has been seen with every anti-HIV drug. If someone has laboratory evidence of resistance to a drug, it does not mean that every strain of HIV in the person's body is resistant, so there might still be some merit to taking the drug, especially if there are no other treatment options. Drugs are used in combination to discourage resistance.

Retina: The portion of the eye onto which images are projected; CMV affects this part of the eye, and it can become detached from the rest of the eyeball. Inflammation of the retina is called "retinitis."

Retinitis: see entry above.

Retrovir®: see "AZT."

Retrovirus: A type of virus (like HIV) that encodes its genes as RNA, rather than DNA. Human cells use DNA to encode their genetic information; for retroviruses to incorporate their genes into human genes, they must be able to convert RNA into DNA. The enzyme reverse transcriptase accomplishes this conversion.

Ritonavir (Norvir®): A protease inhibitor that needs to be taken with food. It must be kept refrigerated. Ritonavir interacts with several drugs, so be sure the doctor who prescribes it knows everything you are taking. Main side effects are nausea and diarrhea.


Saquinavir (Invirase® and Fortovase®): A protease inhibitor; the original form of saquinavir (Invirase®) is poorly absorbed, but a new version (Fortovase®), now in pharmacies, delivers 300% more drug to the bloodstream. Both forms are often taken with ritonavir, which increases the amount of saquinavir that is absorbed.

Sepsis: Overwhelming bacterial infection in the blood. Symptoms include fever and low blood pressure. Sepsis can be life-threatening if not treated promptly.

Serostatus: A generic term that refers to the presence/absence of antibodies in the blood. Often, the term refers to HIV antibodies.

Shingles (Herpes Zoster): This is the adult form of chicken pox. Caused by the Varicella zoster virus, it results in a skin eruption of oozing vesicles on a reddened base, along the distribution of a nerve (an area called a "dermatome"). In the vast majority of cases, only one side of the body is affected. Usually, the condition is very painful; pain often precedes the skin lesions. Several treatments are available.

Side Effect: Any unwanted effect of a drug or treatment (also called an "adverse event"; see entry). Some side effects are minor; others can be life-threatening.

Sinusitis: Inflammation of the sinuses; headache and cold symptoms are usually present.

Spinal tap: see "Lumbar Puncture."

Sporanox®: see "Itraconazole."

Sputum analysis: A test done on fluid coughed up from the lungs; often used to diagnose PCP and TB. Sputum can be induced with a saline mist that causes deep coughing.

Stavudine: see "d4T."

STD: Any sexually-transmitted disease, like gonorrhea, syphilis, HIV, etc.

Steroid: A class of molecules that contain a similar chemical core. The natural function of steroids is as hormonal messengers in the body. Synthetic versions are administered as drugs because of their ability to reduce inflammation.

St. John's Wort: see "Hypericin."

Subcutaneous: Beneath the skin; an area that is rich in fat and blood vessels. Some drugs are injected into this area to aid their absorption.

Surrogate marker: Something that indirectly reflects the patient's current clinical condition. For example, the number of T cells tells us something about how much damage HIV has done, but it is not a direct measure of how much virus is present.


TB: see "Tuberculosis."

Testosterone: A male hormone (also present in females, in low concentrations) that affects muscle mass; it can be used therapeutically in people with HIV infection to promote weight gain and improve sex drive.

3TC (lamivudine, Epivir®): An anti-HIV drug that is in the nucleoside analog class. Now available in a formulation with AZT known as Combivir®, 3TC is well tolerated by most patients.

Thrombocytopenia: An abnormally low platelet count.

Thrush: see "Candida."

T.I.D.: Latin term meaning that pills should be taken three times a day.

TMP/SMX: see "Bactrim®."

Topical: Applied directly to the skin or mucous membranes (such as the mouth, anus, or vagina).

Total Parenteral Nutrition: see "TPN."

Toxicity: Undesirable side effects of a drug or treatment; can range from annoying to life-threatening.

Toxoplasmosis: An infection of the brain, caused by an organism called a protozoan. Many people have are infected by this bug without knowing it. Symptoms include fever, headache, confusion, seizures and, if untreated, coma. Toxoplasmosis is a risk for people with very low T cell counts. If you get it, you will need to take medication indefinitely, to prevent it from coming back.

TPN (Total Parenteral Nutrition): A formula that provides all the calories and nutrients necessary to support life. TPN must be given by a central catheter.

Tuberculosis (TB): An infection caused by an atypical bacterium called a mycobacterium. TB can cause disease in the lungs or outside of the lungs. Most cases in people with HIV infection involve a reactivation; original exposure may have been years earlier. Symptoms include weight loss, fever, and cough, often with blood-streaked mucus. Pulmonary TB (i.e. in the lungs) requires that a patient be kept in isolation until he is no longer infectious, since the bug causing TB is airborne and easily transmissible. You can be tested for prior exposure to TB (see "PPD"). TB is difficult to treat and requires multiple drugs.


Vaccine: A molecule that causes an immune response. Vaccines usually consist of a small portion of the organism (often a virus) we want to avoid. Some vaccines are weakened or killed versions of the organism. The idea is to "educate" the immune system so that exposure will not catch the body off guard; it will already have antibodies designed to neutralize the bug. Most vaccines are safe and desirable in people with HIV infection, but live, weakened ones are to be avoided.

Valaciclovir (Valtrex®): A medication to treat herpes infections. Valaciclovir turns into acyclovir (the original anti-herpes drug) in the bloodstream, but it delivers larger amounts of the drug than acyclovir itself. The advantage is that fewer pills need to be taken.

Valtrex®: see entry above.

Videx®: see "ddI."

Viracept®: see "Nelfinavir."

Viral Load: The amount of virus in a given sample of body fluid (usually blood). Measurements are with a lab technique called PCR (see entry). Viral load measurements can be used to judge how active HIV is and if current treatment is working well.

Viramune®: see "Nevirapine."

Virology: The study of viruses.

Virulence: The ability of a bug to cause disease.

Virus: A particle containing genetic information and therefore able to reproduce. Its genes may be in the form of DNA or RNA (see "Retrovirus"). Technically, a virus is not a living organism, because it cannot reproduce without infecting living cells. It is notoriously difficult to design drugs that effectively treat viruses.


Zalcitabine: see "ddC."

ZDV: see "AZT."

Zerit®: see "d4T."

Zidovudine: see "AZT."

Zithromax®: see "Azithromycin."

Zovirax®: see "Acyclovir."

A note from The field of medicine is constantly evolving. As a result, parts of this article may be outdated. Please keep this in mind, and be sure to visit other parts of our site for more recent information!

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This article was provided by San Francisco General Hospital. It is a part of the publication AIDS Care.
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