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• AIDS HIV Terms

AIDS-HIV Related Terms

- C -

• Cachexia

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



• Candida

Yeast-like fungi commonly found in the normal flora of the mouth, skin, intestinal tract, and vagina, which can become clinically infectious in immune-compromised persons. See Candidiasis, Fungus, Thrush.



• Candidiasis

An infection with a yeast-like 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 deterioration. See Opportunistic Infection; Thrush; Vaginal Candidiasis.



• Carcinogen

Any cancer-producing substance.



• Cat Scan

See C-T Scan.



• CBC

See Complete Blood Count.



• CBCT

See Community-Based Clinical Trial.



• CBO

See Community-Based Organization.



• CCR5

Cell surface molecule, which is needed along with the primary receptor, the CD4 molecule, in order to fuse with the membranes of the immune system cells. Researchers have found that the strains of HIV most often transmitted from person to person require the CCR5 molecule and CD4 molecule in order for HIV to enter the cell. In addition to its role in fusion, CKR5 is a receptor for certain immune-signaling molecules called chemokines that are known to suppress HIV infection of cells. See Chemokines; CXCR4.



• CDC

See Centers for Disease Control and Prevention.



• Cdc National AIDS Hotline (CDC-NAH)

Provides education, information, and referrals for persons living with HIV, their families and friends, health professionals, and the general public on HIV/AIDS issues, including risk factors, transmission, prevention, and testing. The Hotline number is 1-800-342-AIDS (1-800-342-2437). Internet Address



• Cdc National Prevention Information Network (CDC-NPIN)

The National Prevention Information Network (NPIN) is a national reference, referral and distribution service for information on HIV/AIDS, STDs, and TB, sponsored by the Centers for Disease Control and Prevention (CDC). All of the NPIN's services are designed to facilitate sharing of information and resources among people working in HIV, STD, and TB prevention, treatment, and support services. NPIN staff serves a diverse network of people who work in international, national, state, and local settings. Internet address



• Cell Lines

Specific cell types artificially maintained in the laboratory (i.e., in vitro) for scientific purposes.



• Cell-Mediated Immunity (CMI)

This branch of the immune system exists primarily to deal with viruses, which are more insidious than bacteria because they invade the host (e.g., human) cells, where they can hide from the antibody-making cells of the immune system. With this system, the reaction to foreign material is performed by specific defense cells, such as killer T cells, macrophages, and other white blood cells rather than by antibodies.



• Cellular Immunity

See Cell-Mediated Immunity.



• 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. CDC operates 11 Centers including the National Center for HIV, STD, and TB Prevention. CDC assesses the status and characteristics of the HIV epidemic and conducts epidemiologic, laboratory, and surveillance investigations. Internet address



• Centers For Medicare And Medicaid Services (CMS)

A federal agency within the U.S. Department of Health and Human Services. CMS runs the Medicare and Medicaid programs, two national health care programs that benefit about 75 million Americans. And with the Health Resources and Services Administration, CMS runs the State Children's Health Insurance Program (SCHIP), a program that is expected to cover many of the approximately 10 million uninsured children in the United States. CMS also regulates all laboratory testing (except research) performed on humans in the United States. (Formerly the Health Care Financing Administration (HCFA)). Internet address



• Central Nervous System

The central nervous system is composed of the brain, spinal cord, and meninges (protective membranes surrounding them).



• Central Nervous System (CNS) Damage

(By HIV infection.) Although monocytes and macrophages can be infected by HIV, they 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. Investigators have hypothesized that an accumulation of HIV in brain and nerve cells or the inappropriate release of cytokines or toxic byproducts of these cells may be to blame for the neurological manifestations of HIV disease.



• Cerebral

Pertaining to the cerebrum, the main portion of the brain.



• Cerebrospinal Fluid (CSF)

Fluid that bathes the brain and the spinal cord. A sample of this fluid is often removed from the body for diagnostic purposes by a lumbar puncture (spinal tap). See Lumbar Puncture.



• Cervical Cancer

A malignant neoplasm 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 a precursor lesion for cervical cancer. Studies indicate an increase in prevalence of cervical dysplasia among women living with HIV. Additional studies have documented that a higher prevalence is associated with greater immune suppression. HIV infection also may adversely affect the clinical course and treatment of cervical dysplasia and cancer.



• Cervical Intraepithelial Neoplasia (CIN1, CIN2, CIN3)

Dysplasia of the cervix epithelium, often premalignant (i.e., precancerous). Considerable evidence implicates human papilloma virus (HPV) in the development of CIN. Immunosuppression may also play an important role in facilitating infection or persistence of HPV in the genital tract and progression of HPV-induced neoplasia. See Condyloma; Neoplasm.



• Cervix

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



• Challenge

In vaccine experiments, the deliberate exposure of an immunized animal to the infectious agent.



• Chancroid

A highly contagious sexually transmitted disease caused by the Haemophilus ducreyi bacterium with symptoms appearing 3 to 5 days after exposure. It appears as a tender papule that becomes pustular and then ulcerative.



• Chemokines

Also called beta chemokines. Studies of the relationship between HIV and these immune system chemicals have shown the complex exchanges that take place when HIV and white blood cells meet. Chemokines are intracellular messenger molecules secreted by CD8+ cells whose major function is to attract immune cells to sites of infection. Recent research has shown that HIV-1 needs access to chemokine receptors on the cell surface to infect the cell. Several chemokines-called RANTES, MIP-1A, and MIP-1B-interfere with HIV replication by occupying these receptors. Findings suggest that one mechanism these molecules use to suppress HIV infectivity is to block the process of fusion used by the virus to enter cells.



• Chemoprophylaxis

The use of a drug or chemical to prevent a disease.



• Chemotherapy

In general, it is the use of medications to treat any disease. It is more commonly used to described medications to treat cancer. The treatment, mostly of cancer, uses a series of cytotoxic drugs that attack cancerous cells. This treatment commonly has adverse side effects that may include the temporary loss of the body's natural immunity to infections, loss of hair, digestive upset, and a general feeling of illness. Although unpleasant, the adverse effects of treatment are tolerated considering the life-threatening nature of the cancers.



• Chlamydia

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.



• Chronic Idiopathic Demyelinating Polyneuropathy (CIPD)

Chronic, spontaneous loss or destruction of myelin. Myelin is a soft, white, somewhat fatty material that forms a thick sheath around the core of myelinated nerve fiber. Patients show progressive, usually symmetric weakness in the upper and lower extremities. Patients with clinical progression of the syndrome after 4 to 6 weeks by definition have CIPD. Treatment in most centers consists of giving IV-immune globulin for 4 to 5 days or plasmapheresis (5 to 6 exchanges over 2 weeks).



• CIPD

See Chronic Idiopathic Demyelinating Polyneuropathy.



• Circumoral Paresthesia

An abnormal sensation, such as burning or prickling around the mouth, often in the absence of an external stimulus. See Paresthesia.



• CLADE

Also called a subtype. A clade is a group of related HIV isolates classified according to their degree of genetic similarity (such as the percentage of identity within their envelope genes). There are currently three groups of HIV-1 isolates M, N, and O. Isolate M (major strains) consists of at least ten clades, A through J. Group O (outer strains) may consist of a similar number of clades. French researchers reported the discovery of a new HIV-1 isolate that cannot be categorized in either group M or O. The new isolate was found in a Cameroonian woman with AIDS. They suggested that this new isolate be classified as group N (for new or for 'non-M-non-O'). See Isolate.



• Clinical

Pertaining to or founded on observation and treatment of patients, as distinguished from theoretical or basic science.



• Clinical Alert

The National Institutes of Health, in conjunction with the editors of several biomedical journals, publish these bulletins on urgent cases in which timely and broad dissemination of results of clinical trials could prevent morbidity (sickness) and mortality (death). The Clinical Alert does not become a barrier to subsequent publication of the full research paper. Clinical Alerts are widely distributed electronically through the National Library of Medicine and through standard mailings. Internet Address



• 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. Even early in the disease, HIV is active within lymphoid organs where large amounts of virus become trapped in the follicular dendritic cells (FDC) network. Surrounding tissues are areas rich in CD4+ T cells. These cells increasingly become infected, and viral particles accumulate both in infected cells and as free virus.



• Clinical Practice Guidelines

Systematically developed statements by panels of expert practitioners to assist clinicians and patients in making decisions about appropriate health care for specific clinical circumstances. Internet Address (National Guideline Clearinghouse)



• Clinical Trial

A scientifically designed and executed investigation of the effects of an intervention (drug, vaccine, biologic or behavioral) administered to human subjects. The goal is to define the safety, clinical efficacy, and pharmacological effects (including toxicity, side effects, incompatibilities, or interactions) of the drug. The U.S. government, through the FDA, requires strict testing of all new drugs and vaccines prior to their approval for use as therapeutic agents. See Phase I, II, III, and IV Trials.



• Clinicaltrials.Gov

A service of the National Institutes of Health through its National Library of Medicine that provides a comprehensive database of clinical trials for all serious and life-threatening diseases, including HIV/AIDS. The website is designed to provide patients, family members and members of the public with current information about clinical research studies and other trial information. Internet address



• CLONE

1. A group of genetically identical cells or organisms descended from a common ancestor. 2. To produce genetically identical copies. 3. A genetically identical replication of a living cell that is valuable for the investigation and reproduction of test cultures.



• CMS

See Centers for Medicare and Medicaid Services.



• CMV

See Cytomegalovirus.



• Cmv Retinitis

See Cytomegalovirus Retinitis.



• CNS

See Central Nervous System.



• Coccidioidomycosis

An infectious fungal disease caused by the inhalation of spores of Coccidioides immitis, which are carried on windblown dust particles. The disease is endemic in hot, dry regions of the Southwestern United States and Central and South America. It is considered an AIDS-defining opportunistic infection in persons with HIV infection. Also called desert fever, San Joaquin Valley fever, or Valley fever. See Fungus; Opportunistic Infection.



• CODON

A sequence of three nucleotides of messenger RNA that specifies addition of a particular amino acid to, or termination of, a polypeptide chain during protein synthesis. See Ribonucleic Acid.



• Cofactors

1. Substances, micro-organisms, or characteristics of individuals that may influence the progression of a disease or the likelihood of becoming ill. 2. A substance, such as a metallic ion or coenzyme, that must be associated with an enzyme for the enzyme to function. 3. A situation or activity that may increase a person's susceptibility to AIDS. Examples of cofactors are other infections, drug and alcohol use, poor nutrition, genetic factors, and stress. In HIV immunology, the concept of cofactors is being expanded and new cofactors have been identified. A recent example is the discovery of the interaction of CXCR4 (fusin) and CD4 to facilitate entry of HIV into cells.



• Cognitive Impairment

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



• Cohort

In epidemiology, a group of individuals with some characteristics in common.



• Colitis

Inflammation of the colon.



• Combination Therapy

Two or more drugs or treatments used together to achieve optimum results against HIV infection and/or AIDS. Combination drug therapy has proven more effective in decreasing viral load than monotherapy (single-drug therapy). An example of combination therapy would be the use of two nucleoside analog drugs plus either a protease inhibitor or a non-nucleoside reverse transcription inhibitor. See Synergism.



• Community Planning

Community planning groups are responsible for developing comprehensive HIV prevention plans that are directly responsive to the epidemics in their jurisdictions. The goal of HIV Prevention Community Planning is to improve the effectiveness of HIV prevention programs. Together in partnership, representatives of affected populations, epidemiologists, behavioral scientists, HIV/AIDS prevention service providers, health department staff, and others analyze the course of the epidemic in their jurisdiction, determine their priority intervention needs, and identify interventions to meet those needs. CDC supports implementation of an effective planning process.



• Community Programs For Clinical Research On AIDS (CPCRA)

The CPCRA, founded in 1989, and called the Terry Beirn Community Programs for Clinical Research on AIDS since 1992, is a network of research units composed of community-based health care providers who offer their patients the opportunity to participate in research where they get their health care. The 15 CPCRA units comprise a variety of clinical settings, including private physicians' practices, university, and veterans' hospital clinics; drug treatment centers; and freestanding community clinics. Patients at these clinics are eligible for participation in CPCRA studies. The CPCRA, funded by the National Institute of Allergy and Infectious Disease (NIAID), is targeted to serve populations underrepresented in previous clinical trials efforts. The research focus and scientific agenda of the CPCRA is identifying and improving treatment options in the day-to-day clinical care of people with HIV. Internet address



• Community-Based Clinical Trial (CBCT)

A clinical trial conducted primarily through primary-care physicians rather than academic research facilities.



• Community-Based Organization (CBO)

A service organization that provides social services at the local level.



• Compassionate Use

A method of providing experimental therapeutics prior to final FDA approval for use in humans. This procedure is used with very sick individuals who have no other treatment options. Often, case-by-case approval must be obtained from the FDA.



• Complement

A group of proteins in normal blood serum and plasma that, in combination with antibodies, causes the destruction of antigens, particularly bacteria and foreign blood cells.



• Complement Cascade

A precise sequence of events, usually triggered by an antigen-antibody complex, in which each component of the complement system is activated in turn. See Antibodies; Antigen.



• Complementary And Alternative Therapy

Broad range of healing philosophies, approaches, and therapies that Western (conventional) medicine does not commonly use to promote well being or treat health conditions. Examples include acupuncture, herbs, etc. For more information contact the NCCAM. See Alternative Medicine.



• Complete Blood Count (CBC)

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



• Computed Tomography Scan (C-T SCAN)

See C-T Scan.



• Concomitant Drugs

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



• Condyloma

A wart-like 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 and autoinoculable (i.e., capable of being transmitted by inoculation from one part of the body to another). Also called genital warts, venereal warts, or verruca acuminata.



• Contagious

In the context of HIV, has come to be more popularly known as any infectious disease capable of being transmitted by casual contact from person to another. Casual contact can be defined as normal day-to-day contact among people at home, school, work, or in the community. A contagious pathogen (e.g., chicken pox) can be transmitted by casual contact. An infectious pathogen, on the other hand, is transmitted by direct or intimate contact (e.g., sex). HIV is infectious, not contagious.



• Contraindication

A specific circumstance when the use of certain treatments could be harmful.



• Controlled Trials

Control is a standard against which experimental observations may be evaluated. In clinical trials, one group of patients is given an experimental drug, while another group (i.e., the control group) is given either a standard treatment for the disease or a placebo.



• CORE

The protein capsule surrounding a virus' DNA or RNA. In HIV, p55, the precursor molecule to the core, is broken down into the smaller protein molecules of p24, p17, p7, and p6. HIV's core is primarily composed of p24.



• Core Protein

See Core.



• Co-Receptors

A group of proteins that have been found to block the entry of HIV into immune cells.



• Correlates Of Immunity/Correlates Of Protection

The immune responses that protect an individual from a certain disease. The precise identities of the correlates of immunity in HIV are unknown.



• CPCRA

See Community Programs for Clinical Research on AIDS.



• Creatinine

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.



• Cross-Resistance

The phenomenon in which a microbe that has acquired 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. Cross-resistance arises because the biological mechanism of resistance to several drugs is the same and arises through the identical genetic mutations.



• Cryotherapy

The use of liquid nitrogen to freeze and destroy a lesion or growth, sometimes used to induce scar formation and healing to prevent further spread of a condition.



• 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; Cryptococcosis.



• Cryptococcosis

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 impaired immune systems this organism can cause disease.



• Cryptosporidiosis

A diarrheal disease caused by the protozoa Cryptosporidium which 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. Cryptosporidiosis usually occurs late in the course of HIV disease as immunological deterioration progresses. See Cryptosporidium.



• Cryptosporidium

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.



• CSF

See Cerebrospinal Fluid.



• C-T Scan (COMPUTED TOMOGRAPHY SCAN)

Radiography (using x-rays). An x-ray in which a three-dimensional image of a body structure is constructed by computer from a series of cross-sectional images made along an axis. Also called CAT scan. See Magnetic Resonance Imaging (MRI).



• CTL

See Cytotoxic T Lymphocyte.



• Cutaneous

Of, pertaining to, or affecting the skin.



• CXCR4

A cell molecule that acts as a cofactor or co-receptor for the entry of HIV into immune system cells. Early in the epidemic, CD4 molecules were found to be the primary receptor for HIV on immune system cells. Recent data indicate that a second molecule, CXCR4, is also required for fusion and entry of certain strains of HIV into cells. New studies indicate a multistage interplay between HIV and two receptors on white blood cells. After binding to the receptor CD4, the virus fuses with a second receptor, CXCR4, which normally binds to chemokines. This double clasp may then signal the receptors to move the virus into the cell. Also called fusin.



• Cytokines

A protein produced by white blood cells, that acts as a messenger between cells. Cytokines can stimulate or inhibit the growth and activity of various immune cells. Cytokines are essential for a coordinated immune response and can also be used as immunologic adjuvants. HIV replication is regulated by a delicate balance among the body's own cytokines. By altering that balance one can influence the replication of the virus in the test tube and potentially even in the body. See also Interleukins; Tumor Necrosis Factor.



• Cytomegalovirus (CMV)

A common herpes virus that is a common cause of opportunistic diseases in persons with AIDS and other persons with immune suppression. Most adults in the U.S. have been infected by CMV; 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 or suppressed 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 Retinitis.



• Cytomegalovirus (CMV) Retinitis

An eye disease 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.



• Cytopenia

Deficiency in the cellular elements of the blood.



• Cytotoxic

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



• Cytotoxic T Lymphocyte (CTL)

A lymphocyte 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. CTLs kill virus-infected cells, whereas antibodies generally target free-floating viruses in the blood. See also CD8 (T8) Cells.