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HIV testing: a practical approach
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Definitions |
Antibody - produced by the body's immune system in response to an outside body that causes disease, such as a virus or bacteria. Antibodies are specific to the particular virus or bacteria.
Antigen - the part of a virus or bacteria that the immune system recognises as being an intruder
Anonymous linked testing - HIV testing where the results cannot be linked to the person whose blood has been tested, except with the consent of that person. Usually the person uses a false name, a number or code to preserve their identity.
Anonymous unlinked testing - HIV testing where the results cannot be linked with the person whose blood has been tested, for example by not putting a name on the sample
Antiretroviral therapy (ART) - treatment with drugs that affect the virus itself
Assay - a test designed to detect a specific substance, such as antibodies to a virus
Asymptomatic - when a person has HIV infection but is well and has no signs or symptoms of HIV-related illness
Batch testing - testing a large number of samples at one time
Compulsory testing - see 'Mandatory testing'
Confidentiality - when information about a person is not passed on to anyone else other than the person who has been tested
Confirmatory testing - when a supplementary test is used to confirm an initial positive diagnosis of HIV infection
Discordant couples - couples where one person is HIV-positive and the other is HIV-negative
Enzyme linked immunosorbent assay (ELISA) - test that detects antibodies, such as HIV
False negative - a negative test result when the blood sample is infected with HIV
False positive - a positive test result when the blood sample is not infected with HIV
Immune system - the body's defence system against attack from viruses, bacteria and other harmful organisms
Incidence - the number of new infections per year in a given population
Informed consent - when a person agrees voluntarily to be tested after they have fully understood what the test involves and what the result may mean
Mandatory testing - when a person is tested without being given a choice
Opportunistic infections - common infections in people whose immune system is damaged, that do not usually affect people with a healthy immune system
Polymerase chain reaction (PCR) - a test that can detect the viral genetic material of HIV
Prevalence - the percentage of a population that has a particular disease at a particular point in time
Prophylaxis - measures taken to prevent a disease or illness
Rapid assays or tests - HIV tests that can be performed in less than 10 minutes
Reagent - an agent capable of producing a chemical reaction
Routine testing - where people are tested as a matter of course, sometimes without their knowledge, unless they specifically refuse testing
Screening - systematic testing of particular groups of people, or of donated blood, tissue and organs before use in transfusions or transplants
Sensitivity - the likelihood (expressed as a percentage) that a test result will be positive when antibodies to HIV are present
Seronegative - when a blood sample has been tested for HIV and shows no antibodies to HIV
Seropositive - when a blood sample has been tested for HIV, and the result has been confirmed, and shows antibodies to HIV
Seroprevalence - the percentage of a population infected with HIV
Serostatus (HIV status) - the status of a person's blood - whether the blood has antibodies to HIV (seropositive) or not (seronegative)
Serum - the part of the blood that contains antibodies
Simple assays or tests - HIV tests that can be performed in 30 minutes to 2 hours
Specificity - the likelihood (expressed as a percentage) that a test result will be negative if HIV antibodies are not present
Supplementary test - a test used to confirm an initial positive diagnosis of HIV infection
Surveillance - anonymous unlinked testing of specific groups of people to detect levels of HIV infection in a population. Surveillance is normally used to identify trends in the epidemic and to plan allocation of resources.
Testing - refers in this publication to testing for HIV Viral culture - a test that detects the virus itself, by trying to culture (grow) the virus from a blood sample
Voluntary testing - HIV testing of a person who has given informed consent
Western blot - a type of supplementary test used to confirm a diagnosis of HIV, usually when the results of screening are indeterminate (unclear)
Window period - the time between a person being infected with HIV and their body producing enough HIV antibodies for a test to detect
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