A human immunodeficiency virus (HIV) test detects HIV antibodies or antigens or the genetic material (DNA or RNA) of HIV in the blood or another type of sample. This determines whether an HIV infection is present (HIV-positive). HIV infects white blood cells called CD4+ cells, which are part of the body's immune system that help fight infections. HIV can progress to acquired immunodeficiency syndrome (AIDS).
After the original infection, it takes about 4 to 12 weeks for HIV antibodies or antigens to appear in the blood. The period between becoming infected with HIV and the point at which antibodies or antigens to HIV can be detected in the blood is called the seroconversion or "window" period. During this period, an HIV-infected person can still spread the disease, even though a test will not detect any antibodies or antigens in his or her blood.
Several tests can find antibodies to or genetic material (RNA) of the HIV virus. These tests include:
If HIV antibodies or antigens are not found, the test may be repeated in a few months.
If you have a positive test result, contact your sex partners to inform them. They may want to be tested. You may be able to get help from your local health unit to do this.
A test for the human immunodeficiency virus (HIV) is done to:
This test is not done to determine if a person has AIDS. A diagnosis of AIDS means a person is HIV-positive and other problems are present.
You do not need to do anything before you have this test.
A test for HIV infection can't be done without your consent. Most doctors offer counseling before and after the test to discuss:
Before the test, it is important to tell your doctor how and where to contact you when your test results are ready. If your doctor has not contacted you within 1 to 2 weeks of your test, call and ask for your results.
The health professional drawing blood will:
You may feel nothing at all from the needle puncture, or you may feel a brief sting or pinch as the needle goes through the skin. Some people feel a stinging pain while the needle is in the vein. But many people do not feel any pain (or have only minor discomfort) once the needle is positioned in the vein. The amount of pain you feel depends on the skill of the health professional drawing the blood, the condition of your veins, and your sensitivity to pain.
There is very little risk of complications from having blood drawn from a vein.
A human immunodeficiency virus (HIV) test detects HIV antibodies or antigens, or the genetic material (DNA or RNA) of HIV in blood or another type of sample. ELISA results are usually available in 2 to 4 days. Results of other tests may take longer to be available.
No HIV antibodies or antigens are found. Normal results are called negative.
If a test is done during the seroconversion period and is negative, repeat testing is needed. Most people have HIV antibodies or antigens within 3 months after becoming infected. If a repeat test is negative, there is no infection.
A PCR test to look for genetic material does not detect any RNA or DNA of HIV.
Test results do not clearly show whether a person has an HIV infection. This is usually called an indeterminate result. It may occur before HIV antibodies or antigens develop or when some other type of antibody or antigen is interfering with the results. If this occurs, a PCR test, which detects HIV RNA or DNA, may be done to see if the virus is present.
A person who still has indeterminate results for 3 months or longer is called "stable indeterminate" and is not considered to be infected with HIV.
HIV antibodies or antigens are found. These results are called positive.
A positive ELISA is repeated using the same blood sample. If two or more ELISA results are positive, they must be confirmed by another test, such as a PCR test.
A PCR test finds genetic material (RNA or DNA) of HIV.
Reasons you may not be able to have the test or why the results may not be helpful include:
Other Works Consulted
Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
Pagana KD, Pagana TJ (2010). Mosby's Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.
U.S. Department of Health and Human Services Panel on Antiretroviral Guidelines for Adults and Adolescents (2015). Guidelines for the use of antiretroviral agents in HIV-1-infected adults and adolescents. U.S. Department of Health and Human Services. http://aidsinfo.nih.gov/contentfiles/lvguidelines/adultandadolescentgl.pdf. Accessed May 5, 2015.
ByHealthwise StaffPrimary Medical ReviewerE. Gregory Thompson, MD - Internal MedicineBrian O'Brien, MD, FRCPC - Internal MedicineAdam Husney, MD - Family MedicinePeter Shalit, MD, PhD - Internal Medicine, Infectious Disease
Current as ofNovember 18, 2017
Current as of: November 18, 2017
E. Gregory Thompson, MD - Internal Medicine
& Brian O'Brien, MD, FRCPC - Internal Medicine & Adam Husney, MD - Family Medicine & Peter Shalit, MD, PhD - Internal Medicine, Infectious Disease
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