If you're worried that you might have been exposed to human immunodeficiency virus ( HIV) -- the virus that causes AIDS -- it's important to get tested as soon as possible. Although the prospect of being diagnosed with the disease can be scary, today you can live a long and full life with HIV, especially if you start treatment early. Knowing you are infected can also help you take precautions so that you don't pass the virus to other people.
HIV Tests: Getting a Diagnosis
You are at risk for HIV infection and should be tested for it if:
- You’ve had several sexual partners
- You had unprotected sex with someone who is or could be HIV-positive.
- You have used injected drugs or steroids or shared needles or other equipment during drug use
- You have had any sexually transmitted disease, including herpes, hepatitis, or TB
- You have had sex for drugs or money
- You’ve had sex with someone who has a history of any of the above -- or with someone whose sexual history you don’t know
There are several tests used to diagnose HIV infection:
Antibody tests. If you are infected with the HIV virus, your body will start to produce infection-fighting proteins against the virus, called antibodies. HIV antibody tests look for these proteins in the blood or other body fluids.
The most common HIV test, the enzyme-linked immunosorbent assay, or ELISA (also called EIA), is used to detect HIV antibodies in a sample of the blood. Other versions of the antibody HIV test use a sample of saliva or urine.
Although HIV tests are very sensitive, they can produce false-positive results. So ELISA HIV tests must be confirmed with another HIV test, such as a Western blot or indirect immunofluorescence assay (IFA).
Antibodies won't show up in the blood or body fluid immediately after you've been infected. There is a "window period" of six to 12 weeks, and sometimes several months, before the body starts producing antibodies to the virus. So even if you tested negative within a few weeks of being exposed to HIV, you should get tested again at three months and six months. Important note: The HIV virus is transmissible during the window period, even though the test may come back as negative.
Rapid HIV tests are based on the same principles as other antibody HIV tests, but they can detect antibodies in blood or saliva much faster -- within about 20 minutes. The results of a rapid HIV test also must be confirmed with a follow-up test before doctors can firmly diagnose HIV. One rapid HIV test, done in a doctor's office, can show HIV antigens as well as antibodies. Antigens appear sooner -- 2 to 4 weeks after being infected -- than antibodies. So, this test can diagnose HIV more quickly after a person is exposed.