HIV ELISA/Western blot is a set of blood tests used to diagnose chronic infection with human immunodeficiency virus (HIV).
Alternative NamesHIV testing
How the test is performedA blood sample is needed. For information on how this is done, see: Venipuncture.
How to prepare for the testNo preparation is necessary.
How the test will feelWhen the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the test is performedTesting for HIV infection is done for many reasons, including:
A negative test result is normal. However, people with early HIV infection (termed acute HIV infection or primary HIV infection) often have a negative test result.
What abnormal results meanA positive result on the ELISA screening test does not necessarily mean that the person has HIV infection. Certain conditions may lead to a false positive result, such as Lyme disease, syphilis, and lupus.
A positive ELISA test is always followed by a Western blot test. A positive Western blot confirms an HIV infection. A negative Western blot test means the ELISA test was a false positive test. The Western blot test can also be unclear, in which case more testing is done.
Negative tests do not rule out HIV infection. There is a period of time (called the "window period") between HIV infection and the appearance of anti-HIV antibodies that can be measured.
If a person might have acute or primary HIV infection, and is in the "window period," a negative HIV ELISA and Western blot will not rule out HIV infection. More tests for HIV will need to be done.
What the risks areVeins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
People who are at high risk (men who have sex with men, injection drug users and their sexual partners, commercial sex workers) should be regularly tested for HIV.
If the health care provider suspects early acute HIV infection, other tests (such as HIV viral load) will be needed to confirm this diagnosis, because the HIV ELISA/Western blot test will often be negative during this window period.
ReferencesDewar R, Goldstein D, Maldarelli F. Diagnosis of human immunodeficiency virus infection. In: Mandell GL, Bennett GE, Dolin R, eds. Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2009:chap 119.
Sax PE, Walker BD. Immunopathogenesis of human immunodeficiency infection. In: Goldman L, Ausiello D, eds. Cecil Medicine.23rd ed. Philadelphia, PA: Saunders Elsevier; 2007:chap 408.
Reviewed ByReview Date: 06/09/2011
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School, Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
HIV ELISA/Western blot is a set of blood tests used to diagnose chronic infection with human immunodeficiency virus (HIV).
Alternative NamesHIV testing
How the test is performedBlood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.
Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.
How to prepare for the testNo preparation is necessary.
How the test will feelWhen the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the test is performedTesting for HIV infection is done for many reasons, including:
A negative test result is normal. However, early HIV infection (termed acute HIV infection or primary HIV infection) often results in a negative test.
What abnormal results meanA positive result on the ELISA screening test does not necessarily mean that the person has HIV infection. There are certain conditions that may lead to a false positive result, such as Lyme disease, syphilis, and lupus.
A positive ELISA test is always followed by a Western blot test. A positive Western blot confirms an HIV infection. A negative Western blot test means the ELISA test was a false positive test. The Western blot test can also be "indeterminate," in which case additional testing is done to clarify the situation.
Negative tests do not rule out HIV infection. There is a period of time (called the "window period") between HIV infection and the appearance of anti-HIV antibodies that can be measured.
If a person might have acute or primary HIV infection, and is in the "window period," a negative HIV ELISA and Western blot will not rule out HIV infection. More tests for HIV will need to be done.
What the risks areVeins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
People who are at high risk (men who have sex with men, injection drug users and their sexual partners, commercial sex workers) should be regularly tested for HIV.
If the health care provider suspects early (acute or primary) HIV infection, other tests (such as HIV viral load) will be needed to confirm this diagnosis, because the HIV ELISA/Western blot test will often be negative during this window period.
ReferencesGoldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, PA: Saunders Elsevier; 2007: sect XXIV.
Yes, 20-45 days after infection. PCR diagnostic test can detect within two weeks of infection
The first test licensed for HIV testing was the ELISA test in 1985. ELISA detects antobodies to the HIV virus, which indicates that the person has been exposed to the virus.
The first blood test for AIDS was developed in 1985. At present, patients who are being tested for HIV infection are usually given an enzyme-linked immunosorbent assay (ELISA) test for the presence of HIV antibody in their blood.
ELISA is an acronym for Enzyme Linked ImmunoSorbent Assay and is used in a wide variety of applications, including detecting antibodies from HIV. See the related link for more information.(Answer by Syama S.):ELISA is a technique used to determine the presence of antigen or antibody in a sample. ELISA is used in diagnosis of HIV... ELISA is of three types: direct method, indirect method and sandwich method. The principle of three methods are same.ELISA is a technique used to determine the presence of antigen or antibody in a sample. ELISA is used in diagnosis of HIV... ELISA is of three types: direct method, indirect method and sandwich method. The principle of three methods are same.
ELISA is a technique used to determine the presence of antigen or antibody in a sample. ELISA is used in diagnosis of HIV... ELISA is of three types: direct method, indirect method and sandwich method. The principle of three methods are same.
The ELISA test is usually the first test given; quick results and inexpensive. See the related link.
You can not conform the presence of HIv with the blood test, you need to go with ELISA, tridot and also western blotting.
Western Blot and ELISA
The ELISA Assay is used quite a lot in testing HIV
The first test performed is ELISA (or EIA) is a test that screens for the presence of HIV antibodies in the blood. This test is not a test for HIV/AIDS its a very sensitive and will be reactive even if there are only 1 or 2 antibodies in that person blood sample. If the results are reactive that test will be followed by a second test called confirmatory test which is highly accurate test in which it's is used to confirm the results of the ELISA.
western blot test
ELISA
I think this would be helpful for you Because early HIV infection often causes no symptoms, a healthcare provider usually can diagnose it by testing blood for the presence of antibodies (disease-fighting proteins) to HIV. The most common test for AIDS is the ELISA (Enzyme-Linked Immuno-Sorbent Assay), which is performed on a blood sample. This test is very sensitive and detects almost all persons infected with the human immunodeficiency virus (HIV) except during the first few weeks of infection. The ELISA test detects the body's immune response to HIV. * In the early 1980s when the HIV/AIDS epidemic began, people with AIDS were not likely to live longer than a few years. With the development of safe and effective drugs, however, people infected with HIV now have longer and healthier lives. * Currently, there are 30 antiretroviral drugs approved by the Food and Drug Administration to treat people infected with HIV. * The best way of self-protection is to learn as much as possible about HIV infection, avoid risky behavior, and follow guidelines for protection. Abstinence, non-penetrative sex or a stable relationship between mutually faithful partners is optimal.