EBV
See: Epstein-Barr Virus

EF
See: Eosinophilic Folliculitis

Effectiveness
The measure of the success of a treatment for a particular disease or condition.

Efficacy
The ability of a treatment to produce the desired effect on the disease or condition being treated.

ELISA
See: Enzyme-Linked Immunosorbent Assay

Encephalitis
Inflammation of the brain, which can be caused by a virus infection. The brain tissue swells, which may lead to the destruction of nerve cells, bleeding within the brain, and brain damage.

End-Stage Disease
The final period or phase in the course of a disease that leads to a person's death. An example of this is end-stage renal disease (ESRD), in which a person's kidneys have deteriorated to the point that the damage is life-threatening and likely fatal.

Endemic
A term that refers to diseases associated with particular geographic regions or populations. For example, malaria is endemic in tropical regions of the world where mosquitoes carry the parasite that causes malaria.

Endpoint
General term for a measurement used to analyze results of a clinical trial. Common endpoints of a clinical trial are dose-limiting toxicity of a study drug and progression of the disease or condition being studied.
See Also:   Surrogate Endpoint

Enteric
Of or relating to the intestines. This term also refers to a coating used on some drugs to prevent the breakdown of the drug by the stomach before it has a chance to be absorbed by the intestines.

Enteritis
Inflammation of the small intestine caused by bacterial or viral infection. Often causes diarrhea and dehydration, and may also involve the stomach and large intestine.
See Also:   Colitis

Entry Inhibitors
A class of anti-HIV drugs designed to disrupt the ability of HIV to enter a host cell through the cell's surface. This class includes receptor inhibitors (CD4, CCR5, or CXCR4) and fusion inhibitors.
See Also:   Fusion Inhibitors

Envelope
The outer protective membrane of HIV, composed of two layers of fat-like molecules called lipids. HIV uses specific proteins embedded in the envelope to attach to and enter host cells.

Enzyme
A protein that helps a chemical reaction happen by decreasing the energy needed for the reaction to occur.

Enzyme-Linked Immunosorbent Assay (ELISA)
A highly sensitive laboratory test used to determine the presence of antibodies to HIV in the blood or saliva. Positive ELISA test results indicate that a person is HIV infected, but these results should be confirmed with a highly specific laboratory test called a Western blot.
See Also:   Western Blot

Eosinophilia
A condition in which the number of eosinophils (a type of white blood cell) in the blood is higher than normal. Eosinophilia is often a response to infection or allergens (substances that cause an allergic reaction).

Eosinophilic Folliculitis (EF)
A type of folliculitis (inflammation of hair follicles) characterized by recurring patches of inflamed, pus-filled sores, primarily on the face and sometimes on the back or upper arms. The sores usually spread, may itch intensely, and often leave areas of darker than normal skin (hyperpigmentation) when they heal. HIV-associated EF most commonly occurs in people with low CD4 counts.

Epidemic
A disease that has spread rapidly through a segment of the human population in a given geographic area.

Epidemiology
The branch of medical science that studies the occurance, distribution, and control of a disease in populations.

Epithelium
The protective covering of the internal and external organs of the body, including the lining of blood vessels, body cavities, glands, and organs. In addition to its protective properties, the epithelium also provides a surface to absorb and secrete chemicals needed by the body.

Epitope
A particular segment of an antigen that the body's antibodies can recognize and bind to.
See Also:   Antibody
                   Antigen

Epstein-Barr Virus (EBV)
A human herpesvirus that causes infectious mononucleosis (mono), a contagious disease. Symptoms of infectious mononucleosis are fever, sore throat, and swollen lymph nodes. EBV infection can also lead to oral hairy leukoplakia, Burkitt's lymphoma and nasopharyngeal carcinoma, especially in immunocompromised people.
See Also:   Burkitt's Lymphoma
                   Human Herpesviruses
                   Oral Hairy Leukoplakia

Erythema
Abnormal redness of the skin caused by a buildup of red blood cells in the capillaries.

Erythema Multiforme
A type of rash that can occur in response to medications, illness, or infections such as herpes simplex or mycoplasma infections. Severe forms of this condition include Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). These may also be serious side effects of some anti-HIV drugs.
See Also:   Stevens-Johnson Syndrome
                   Toxic Epidermal Necrolysis

Erythrocytes
Red blood cells, whose primary function is to carry oxygen throughout the body.

Etiology
The branch of medical science that studies causes of disease. Such causes are called etiologic agents. For example, HIV is the etiologic agent of AIDS.

Exclusion/Inclusion Criteria
See:    Inclusion/Exclusion_Criteria

Expanded Access
Refers to any of the Food and Drug Administration (FDA) procedures that allow distribution of experimental drugs to people who are failing currently available treatments and are unable to participate in ongoing clinical trials. These procedures include compassionate, treatment, or emergency use.
See Also:   Compassionate Use

Experimental Drug
See:    Investigational Drug