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AIDSinfo Glossary Search

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Also known as: Epstein-Barr Virus


Also known as: Enteric-Coated

Ecchymosis Audio (En español)

A blue or purplish bruise that results from bleeding under the skin.

Edema Audio (En español)

Abnormal swelling caused by excess accumulation of fluid in tissues or body cavities.


Also known as: Eosinophilic Folliculitis

Efficacy Audio (En español)

Effectiveness of a drug or other medical intervention. Drugs are tested for efficacy to ensure they produce the desired effect on the disease or condition being treated.

Eligibility Criteria Audio (En español)

Also known as: Exclusion/Inclusion Criteria, Inclusion/Exclusion Criteria

Factors used to determine whether a person is eligible (inclusion criteria) or not eligible (exclusion criteria) to participate in a clinical trial. Eligibility criteria may include disease type and stage, other medical conditions, previous treatment history, age, and gender.

See Related Term(s): Clinical Trial, Protocol


Also known as: Enzyme-Linked Immunosorbent Assay

Elite Controllers Audio (En español)

A very small subset of people infected with HIV who are able to maintain suppressed viral loads for years without antiretroviral (ARV) drugs. Although antiretrovial therapy (ART) may be theoretically beneficial for elite controllers, there is no clinical data supporting therapy for this group.

See Related Term(s): Viral Load

Embryo Audio (En español)

In humans, an infant developing in the uterus (womb) from conception until about the third month of pregnancy.

Encephalitis Audio (En español)

Inflammation of the brain, usually caused by a viral infection. Encephalitis can also be caused by a bacterial infection, toxin, or autoimmune process. Symptoms of encephalitis range from mild, such as flu-like symptoms, to severe, such as seizures. In people with HIV, encephalitis may be due to HIV infection or opportunistic infections, such as Toxoplasma gondii infection.

End-Stage Liver Disease (ESLD) Audio (En español)

The most severe stage of liver disease, at which point the liver is barely functioning, if at all. The treatment for end-stage liver disease (ESLD) is a liver transplant.

See Related Term(s): Liver

End-Stage Renal Disease (ESRD) Audio (En español)

The most severe stage of kidney (renal) disease, at which point the kidneys are barely functioning, if at all. The treatment for end-stage renal disease (ESRD) is dialysis or a kidney transplant.

See Related Term(s): Kidneys

Endemic Audio (En español)

When a disease occurs frequently and at a predictable rate in a specific location or population. For example, HIV-2 is endemic to West Africa.


Also known as: Clinical Endpoint

Enteric Audio (En español)

Pertaining to the intestines. Certain bacterial enteric infections are more common or more severe in people with HIV than in people with healthy immune systems.

Enteric-Coated (EC) Audio (En español)

When a tablet or capsule is coated with a substance that prevents the medication from being released until it reaches the small intestine, where it can then be absorbed.

Enteritis Audio (En español)

Inflammation of the small intestine.

Envelope Audio (En español)

Also known as: HIV Viral Envelope

The outer coat of HIV, made up of two layers of lipids (fatty molecules). HIV uses specific proteins embedded in its envelope to enter host cells.

Enzyme Audio (En español)

A molecule, usually a protein, that catalyzes (increases the rate of) chemical reactions in the body. Enzymes are essential to all body functions. HIV requires specific enzymes, such as reverse transcriptase or integrase, to replicate.

Enzyme Immunoassay

Also known as: Enzyme-Linked Immunosorbent Assay

Enzyme-Linked Immunosorbent Assay (ELISA) Audio (En español)

Also known as: Enzyme Immunoassay

A laboratory test to detect the presence of HIV antibodies in the blood, oral fluid, or urine. The immune system responds to HIV infection by producing HIV antibodies. A positive result on an enzyme-linked immunosorbent assay (ELISA) must be confirmed by a second, different antibody test (a positive Western blot) for a person to be definitively diagnosed with HIV infection.

See Related Term(s): Antibody, Western Blot

Eosinophilia Audio (En español)

An abnormal increase of eosinophils (a type of white blood cell) in the blood, tissues, or organs. Eosinophilia is often a response to infection or allergens (substances that cause an allergic reaction).

Eosinophilic Folliculitis (EF) Audio (En español)

A rare, severe type of folliculitis (inflammation of hair follicles) characterized by itchy bumps or pus-filled sores on the face, chest, back, or arms. Eosinophilic folliculitis (EF) is mainly associated with advanced HIV infection.

Epidemic Audio (En español)

A widespread outbreak of a disease in a large number of individuals over a particular period of time either in a given area or among a specific group of people.

Epidemiology Audio (En español)

The study of the distribution, causes, and clinical characteristics of disease or health status in a population.

Epithelium Audio (En español)

A protective tissue consisting of one or more layers of cells that line the internal surface of organs and glands and cover the outer surface of the body. In addition to enclosing and protecting body surfaces, certain types of epithelial cells produce mucus or use tiny hairs called cilia to help remove foreign substances.

Epitope Audio (En español)

A specific area on the surface of an antigen that interacts with and binds to specific antibodies. Generally, an antigen has several different epitopes.

See Related Term(s): Antibody, Antigen

Epstein-Barr Virus (EBV) Audio (En español)

A type of herpesvirus that infects B lymphocytes (B cells). Epstein-Barr virus (EBV) infection is usually asymptomatic but may cause mononucleosis (“mono”). In people with suppressed immune systems, EBV is strongly associated with certain cancers, including Burkitt lymphoma, oral hairy leukoplakia, and nasopharyngeal carcinoma.

See Related Term(s): Herpesviruses

Eradication Audio (En español)

The total elimination of a pathogen, such as a bacterium, from the body. Eradication can also refer to the complete elimination of a disease from the world, such as the global eradication of smallpox.

Erythema Audio (En español)

Redness of the skin.

Erythema Multiforme Audio (En español)

A type of rash usually triggered by viral infections, most often herpes simplex infection and sometimes HIV infection.


Also known as: Red Blood Cell


Also known as: End-Stage Liver Disease


Also known as: End-Stage Renal Disease

Etiology Audio (En español)

The cause of a disease or abnormal condition. Etiology may also refer to the branch of medical science that studies the causes of diseases.

Excipient Hyperbilirubinemia

Also known as: Kernicterus

Exclusion/Inclusion Criteria

Also known as: Eligibility Criteria

Expanded Access Audio (En español)

Also known as: Compassionate Use

Legal use of an investigational drug outside of a clinical trial to treat a person who has a serious or immediately life-threatening disease and who has no approved treatment options. The Food and Drug Administration (FDA) regulates expanded access to investigational drugs on a case-by-case basis for an individual patient or groups of patients who do not meet criteria to participate in a clinical trial. Drug companies must have permission from the FDA to make an investigational drug available for expanded access.

See Related Term(s): Food and Drug Administration, Investigational Drug

Experimental Arm Audio (En español)

In a clinical trial, the group of participants that is given the experimental treatment being studied. The experimental treatment arm is compared to the control arm to determine whether the experimental treatment works.

See Related Term(s): Clinical Trial, Control Arm

Experimental Drug

Also known as: Investigational Drug

Extensively Drug Resistant Tuberculosis (XDR-TB) Audio (En español)

A relatively rare type of multiple drug resistant tuberculosis (MDR-TB). Extensively drug resistant tuberculosis (XDR-TB) occurs when a Mycobacterium tuberculosis strain becomes resistant to drugs used to treat TB, including the two most effective first-line antibiotics (isoniazid and rifampin) and most of the second-line drugs. XDR-TB progresses more rapidly and is more severe in people coinfected with HIV than in people infected with XDR-TB alone.

See Related Term(s): Multiple Drug Resistant Tuberculosis, Mycobacterium Tuberculosis, Tuberculosis

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