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Glossary of HIV/AIDS Terms

for Health Care Providers

Glossary of HIV/AIDS Terms


The maximum ability of a drug or treatment to produce a result regardless of the drug dosage.


Enzyme-linked immunosorbent assay.



(Enzyme-linked immunosorbent assay) A type of enzyme immunoassay to determine the presence of antibodies to HIV in the blood or oral fluids. Repeatedly (i.e., two or more) reactive ELISA test results should be confirmed with a second, different test such as a rapid HIV test, or a DNA or RNA polymerase chain reaction (PCR). Availability of the confirmatory test often determines which one is performed.


A brain inflammation of viral or other infectious disease origin. Symptoms include headaches, neck pain, fever, nausea, vomiting, and nervous system problems. Several types of opportunistic infections can cause encephalitis.


Any degenerative disease of the brain.


Pertaining to diseases associated with particular locations or population groups.


Relating to or produced by the body.


Viewing the inside of a body cavity (e.g., colon or throat) with an endoscope, a device using flexible fiber optics.


A toxin present inside a bacterial cell.


A category of data used to compare the outcome of a clinical trial. Common endpoints are severe toxicity, disease progression, or death.

End-stage disease

Final period or phase in the course of a disease leading to a person's death.


Pertaining to the intestines.


Inflammation of the intestine.

Entry inhibitors

Compounds designed to prevent the interactions between the HIV virus and the cell surface. These compounds can block or prevent HIV from binding to human cell surface receptors.


A type of white blood cell, called granulocyte, that can digest infectious agents.


The formation and accumulation of an abnormally large number of eosinophils in the blood. Eosinophils are a type of white blood cell that helps to destroy infectious agents. Increased numbers are seen in allergy and parasitic infection.


A disease that spreads rapidly through a part of the human population — such as within a given geographic area, a military base, school, or village — or persons of a certain age group or sex, such as the children or women within a region. Epidemic diseases can be spread from person to person or from a contaminated source such as food or water.

Epidemiologic surveillance

The ongoing organizing and collection, analysis, and interpretation of facts about a disease or health condition.


The branch of medical science that deals with the study and distribution and control of a disease in a population.


The covering of the internal and external organs of the body. Also the lining of blood vessels, body cavities, glands, and organs.

Epstein-Barr virus (EBV)

A herpes-like virus that causes one of the two kinds of mononucleosis (the other is caused by CMV). It infects the nose and throat and is contagious. It has been associated with Burkitt lymphoma and hairy leukoplakia.


Redness or inflammation of the skin or mucous membranes.

Erythema multiforme

A type of hypersensitivity reaction (rash) that occurs in response to drugs, infections, or illness. The exact cause is unknown. A severe form of this condition is called Stevens-Johnson syndrome.

Erythrocyte sedimentation rate (ESR)

A test that measures the rate at which red blood cells settle through a column of liquid. This test is used to detect and monitor inflammation in the body.


Red blood cells whose major function is to carry oxygen to cells.


The study or theory of the factors that cause disease.


The study of a patient to determine the cause and effect of an illness, the study of a set of facts to determine what the facts mean, or the study of a program to determine its effectiveness.

Exclusion/Inclusion criteria

The medical determining of whether a patient may or may not be allowed to participate in a clinical trial. For example, some trials may include persons with chronic liver disease, or may exclude persons with certain drug allergies.

Exclusive breast-feeding

Feeding an infant only breast milk from the mother or a wet nurse, or expressed breast milk and no other liquids or solids with the exception of drops or syrups consisting of vitamins, mineral supplements, or medicines.


Developed or originating outside the body.

Experimental drug

A drug that is not approved or licensed for use in humans.