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Glossary of HIV/AIDS Terms

for Health Care Providers

Glossary of HIV/AIDS Terms


General ill health and malnutrition, marked by weakness and emaciation, usually associated with serious disease.

See AIDS Wasting Syndrome.


Yeastlike fungi commonly found in the normal flora of the mouth, skin, intestinal tract, and vagina, which can become infectious in individuals with an abnormal immune system.

See Candidiasis; Fungus; Thrush.


An infection with a yeastlike fungus of the Candida family, generally Candida albicans. Candidiasis of the esophagus, trachea, bronchi, or lungs is an indicator disease for AIDS. Oral or recurrent vaginal candida infection is an early sign of immune system abnormalities.

See Opportunistic Infection; Thrush; Vaginal Candidiasis.


Any cancer-producing substance.

Casual Contact

Can be defined as normal day-to-day contact among people at home, school, work, or in the community. A contagious infectious agent (e.g. chicken pox, flu) can be transmitted by casual contact.

CD4 (T4) or CD4+ Cells

A type of lymphocyte involved in protecting against viral, fungal, and protozoal infections. They are also known as T helper cells. They are HIV's preferred targets for infection. Destruction of CD4+ lymphocytes is the major cause of the immunodeficiency observed in AIDS, and decreasing CD4+ lymphocyte levels appear to be the best indicator for developing opportunistic infections.

CD4 Count

A test that measures the number of CD4 lymphocytes in the blood, thus reflecting the state of the immune system. A normal count in a healthy adult is 600-1,200 cells/µL. When the CD4 count of an adult falls below 200 cells/µL, there is a high risk of opportunistic infection.

CD4, CD4 Receptor

One of the protein structures on the surface of a human cell that allows HIV to attach, enter, and thus infect the cell. Present on CD4 cells (helper T lymphocytes) among others.

CD8 (T8) Cells

White blood cells (lymphocytes) with the CD8 protein on their surface. These white blood cells kill some cancer cells and cells infected by bacteria and viruses. Also called cytotoxic T cells, T8 cells, cytotoxic T lymphocytes.

Cell-Mediated Immunity (CMI)

Part of the immune system that deals with viruses and other infectious agents as well as cancer cells.

Cellular Immunity

See Cell-Mediated Immunity (CMI).

Centers for Disease Control and Prevention (CDC)

The U.S. Department of Health and Human Services agency with the mission to promote health and quality of life by preventing and controlling disease, injury, and disability.

Central Nervous System (CNS)

The central nervous system is composed of the brain, spinal cord, and meanings (protective membranes surrounding them). The central nervous system is often affected in advanced AIDS, causing dementia.

See AIDS Dementia Complex (ADC).

Central Nervous System (CNS) Damage

Blood monocytes and macrophages that are infected by HIV appear to be relatively resistant to killing. However, these cells travel throughout the body and carry HIV to various organs, especially the lungs and the brain. Persons living with HIV often experience abnormalities in the central nervous system such as dementia (deterioration in intellectual function and emotional disturbances). Investigators have hypothesized that an accumulation of HIV in brain and nerve cells or the inappropriate release of chemical or toxic byproducts of infected cells that reach the central nervous system may be to blame for the neurological manifestations of HIV disease.

Cerebrospinal Fluid (CSF)

Fluid that bathes the brain and the spinal cord.

Cervical Cancer

A cancer of the uterine cervix.

See Cervical Dysplasia; Cervix; Pap Smear.

Cervical Dysplasia

Abnormality in the size, shape, and organization of adult cells of the cervix. It is often found before cancer cells appear. A precursor lesion for cervical cancer. Studies indicate an increase of cervical dysplasia among women living with HIV.

Cervical Intraepithelial Neoplasia (CIN)

An abnormality of the epithelium (lining) of the cervix, often precancerous. Considerable evidence implicates a virus called human papilloma virus (HPV) in the development of CIN.


The lower part of the uterus that extends into the lower vagina and contains a narrow canal connecting the upper and lower parts of a woman's reproductive tract.

Cesarean Section

A delivery procedure for the baby that involves making a cut through the abdominal wall to remove the baby from the uterus.


A highly contagious sexually transmitted disease caused by the Haemophilus ducreyi bacterium with symptoms appearing 3 to 5 days after exposure.

Chemokine Receptor

An alternate receptor used by HIV to infect cells.


Chemokines are messenger molecules secreted by CD8 cells whose major function is to attract immune cells to sites of infection. Several chemokines--called RANTES, MIP-1A, and MIP-1B--interfere with HIV multiplication by occupying these receptors.


In general, it is the use of medicines to treat any disease. It is more commonly used to describe medicines to treat cancer.


A sexually transmitted disease (STD) caused by Chlamydia trachomatis that infects the genital tract. The infection is frequently asymptomatic (i.e. shows no symptoms), but if left untreated, it can cause sterility in women.


An infection of the placental tissues and amniotic fluid occurring during pregnancy. Can cause blood infection in the mother and may lead to premature birth and serious infection in the newborn baby.


Also called a subtype. A clade is a group of related HIV viruses classified according to their degree of virus similarity. There are currently three groups of HIV-1 M, N, and O. Isolate M (major strains) consists of at least 10 clades; A through J. Group O (outer strains) may consist of a similar number of clades.


Pertaining to observations, tests, or treatment of patients.

Clinical Endpoint

See Endpoint.

Clinical Latency

The period of time a virus or bacteria or other organism is living or developing in the body without causing symptoms. The period of time in which a person with HIV infection does not exhibit any evidence of disease or sickness.

Clinical Trial

A scientifically designed study of the effects of a drug, vaccine, biologic, or behavior in humans. The goal is to define the safety, the benefit, and side effects of the drug. Most countries require strict testing of all new drugs and vaccines prior to their approval for use.


An infectious fungal disease caused by the breathing in of Coccidioides immitis, which are carried on windblown dust particles.

Cognitive Impairment

Loss of the ability to process, learn, and remember information.


A group of individuals with some characteristics in common.


Inflammation of the colon, the lower part of the intestine.


The first thick yellow milk secreted by a woman beginning lactation. Colostrum contains high levels of proteins and antibodies.

Combination Therapy

Two or more drugs or treatments used together to obtain the best results against HIV infection and/or AIDS. Combination drug therapy (treatment) has proven more effective than monotherapy (single-drug therapy) in controlling the growth of the virus. An example of combination therapy would be the use of two drugs such as zidovudine and lamivudine together.

Combination Treatment

See Combination Therapy.

Commercial Sex Worker (CSW)

A woman or man who offers sexual intercourse for a fee. The terms prostitute or prostitution are used more frequently used outside the AIDS area.

Community Planning

Community planning groups are responsible for developing HIV prevention, treatment, and care plans that are used in their communities. The goal of HIV community planning is to improve the effectiveness of HIV programs and to be certain that the needs of the community are being met.

Community-Based Organization (CBO)

A service organization that provides social, support, education, and care services at the local level.

Complementary and Alternative Therapy

Broad range of healing approaches and treatments that Western (conventional) medicine does not commonly use to improve health conditions. Examples include acupuncture, herbs, etc.

See Alternative Medicine.

Complementary Feeding

Any food, whether manufactured or locally prepared, suitable as a complement to breast milk or to infant formula, when either become insufficient to satisfy the nutritional requirements of the infant. Such food is commonly called "weaning food" or "breast milk supplement."

Complete Blood Count (CBC)

A frequently ordered blood test that provides the white count, red blood cell count, hematocrit, and hemoglobulin in a microliter of whole blood.

Computed Tomography Scan

See C-T Scan (Computed Tomography Scan).

Concomitant Drugs

Drugs that are taken together. Certain concomitant medications may have adverse interactions.


A wartlike skin growth usually on the external genitalia or perianal area.

Condyloma Acuminatum

A wart in the genital and perianal area. Although the lesions are usually few in number, they may aggregate to form large cauliflower-like masses. Caused by the human papilloma virus (HPV), it is infectious capable of being transmitted from one part of the body to another). Also called genital warts, venereal warts, or verruca acuminata.

Confidential HIV Test

Performing an HIV test and being certain that the result remains confidential.

See Confidentiality.


Relating to a piece of information about a person that should not be given to another person without that person's permission. An example would be the result, whether positive or negative, of an HIV test.


Ensuring that personal medical information is accessible only to those authorized to have access, unless the patient provides consent.

Confirmatory Test

Because the diagnosis of HIV infection is so important, a second test, to show that the first test was correct, is recommended. A confirmatory test for an ELISA test is usually the Western blot. A confirmatory test could also be another HIV test such as a rapid test or a DNA or RNA PCR test.

Confirmed Positive

For HIV, a blood sample that is positive on an initial ELISA test, repeatedly positive on a second ELISA run on the same specimen, or confirmed positive on Western blot or other supplemental test indicates that the client is infected.


Any infectious disease capable of being transmitted by direct or indirect contact from one person to another.


Any condition that renders a particular line of treatment improper or undesirable. Some drugs may be contraindicated when given together (eg, zidovudine and lamivudine).

Controlled Clinical Trials

Performing a study in human in which a control is used. A control is a standard against which study observations may be evaluated. For example, in clinical trials, one group of patients is given an experimental drug, while another group (i.e. the control group) is given either the normal treatment for the disease or a placebo.

Cord Traction

A maneuver in which the umbilical cord is pulled gently with one hand while the other hand pushes the uterus up from the pubis. This is done to prevent uterine inversion.


Also known as trimethoprim/sulphamethoxazole, Bactrim, or Septra. A combination antibiotic drug effective at preventing and treating Pneumocystis jiroveci pneumonia (PCP); also serves as a prophylaxis against toxoplasmosis. The drug is also active against certain bacterial infections.

See Trimethoprim/Sulphamethoxazole.


Confidential dialogue between individuals and their health care providers. The term can refer to discussions between health care workers and clients/patients specific to HIV testing to help clients examine their risk of acquiring or transmitting HIV infection.


A protein found in muscles and blood, and excreted by the kidneys in the urine. The level of creatinine in the blood or urine provides a measure of kidney function.


The process in which an infectious agent that acquires resistance to one drug through direct exposure also turns out to have resistance to one or more other drugs to which it has not been exposed.

Cryptococcal Meningitis

A life-threatening infection of the membranes surrounding the brain and the spinal cord caused by the fungus Cryptococcus neoformans. Symptoms include headache, dizziness, stiff neck, and, if untreated, coma and death.

See Cryptococcus Neoformans.


An infectious disease due to the fungus Cryptococcus neoformans, which is acquired via the respiratory tract. It can spread from the lungs to the central nervous system (especially the membranes surrounding the brain), the skin, the skeletal system, and the urinary tract. It is considered an AIDS-defining opportunistic infection in persons infected with HIV.

See Cryptococcal Meningitis.

Cryptococcus Neoformans

A fungus found in soil contaminated by bird droppings. Most people have been exposed to this organism, which does not usually cause disease in healthy people. In persons with AIDS, this organism can cause illness and death.


A diarrheal disease caused by the protozoa Cryptosporidium that grows in the intestines. Symptoms include abdominal cramps and severe chronic diarrhea. It is considered an AIDS-defining opportunistic infection in persons with HIV infection as immunological deterioration progresses.


The protozoan (parasite Cryptosporidium parvum), which causes Cryptosporidiosis. The parasite is found in the intestines of animals and may be transmitted to humans by direct contact with an infected animal, by eating contaminated food, or by drinking contaminated water. The parasite grows in the intestines and in people with HIV disease causes Cryptosporidiosis.

See Cryptosporidiosis.

C-T Scan (Computed Tomography Scan)

An x-ray in which a three-dimensional image of a body structure is constructed by computer from a series of images.

See Magnetic Resonance Imaging (MRI).


Of, pertaining to, or affecting the skin.

Cytomegalovirus (CMV)

A common herpes virus that is a common cause of opportunistic diseases in persons with AIDS and other persons with immune suppression. CMV has infected most adults; however the virus does not cause disease in healthy people. Because the virus remains in the body for life, it can cause disease if the immune system becomes severely damaged by drugs. While CMV can infect most organs of the body, persons with AIDS are most susceptible to CMV retinitis (disease of the eye) and colitis (disease of the colon).

See Cytomegalovirus (CMV) Retinitis.

Cytomegalovirus (CMV) Retinitis

An eye disease caused by the CMV virus, common among persons who are living with HIV. Without treatment, persons with CMV retinitis can lose their vision. CMV infection can affect both eyes and is the most common cause of blindness among persons with AIDS.

See Cytomegalovirus (CMV).


Deficiency in the cellular elements of the blood.


An agent or process that is toxic or destructive to cells.

Cytotoxic T Lymphocyte (CTL)

A lymphocyte (white blood cell) that is able to kill foreign cells marked for destruction by the cellular immune system. CTLs can destroy cancer cells and cells infected with viruses, fungi, or certain bacteria. CTLs are also known as killer T cells; they carry the CD8 marker.

See CD8 (T8) Cells.