HIV, or human immunodeficiency virus, is the virus that causes AIDS (acquired immune deficiency syndrome). HIV weakens a person's immune system, reducing his or her ability to fight infections and cancers. A person can get HIV by coming into contact with an infected person's body fluids (blood, semen, vaginal fluids, breast milk), and HIV can be spread through:
Vaginal, oral, or anal sex
Sharing unclean needles to take drugs
Pregnancy (from an infected mother to baby)
Blood transfusions (since 1985, blood donations have been routinely tested for HIV, so infection from blood transfusions is rare)
You cannot get HIV from:
Did You Know?
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Sharing cups, utensils, telephones, or other personal items
How Can I Know If I Have HIV?
There are several types of tests that screen blood (and sometimes saliva) to see if you are infected with HIV.
Newer tests can detect the presence of HIV antigen, a protein, up to 20 days earlier than standard tests. This helps prevent spread of the virus to others and start treatment earlier. It is done with a pinprick to the finger.
Here's a look at available HIV tests:
Standard tests. These blood tests check for HIV antibodies. Your body makes antibodies in response to the HIV infection. These tests can't detect HIV in the blood soon after infection because it takes time for your body to make these antibodies. It generally takes two to 8 weeks for your body to produce antibodies, but in some cases it can take up to six months.
In standard tests, a small sample of your blood is drawn and sent to a lab for testing. Some of the standard tests use urine or fluids that are collected from the mouth to screen for antibodies.
Rapid antibody tests. Most of these are blood tests for HIV antibodies. Some can detect antibodies in saliva. Results are available in under 30 minutes and are as accurate as standard tests.
Antibody/antigen tests. These tests can detect HIV up to 20 days earlier than standard tests. They check for HIV antigen, a part of the virus that shows up 2-4 weeks after infection. These tests can also detect HIV antibodies. A positive result for the antigen allows treatment to begin earlier and the patient to avoid infecting others. These are blood tests only.