Human immunodeficiency virus (HIV) is the virus that causes acquired immunodeficiency syndrome (AIDS). HIV can enter the bloodstream through contact with an infected person’s body fluids, such as blood or semen. This can happen during sex or by sharing needles used to inject drugs. An infected woman who is pregnant can pass the virus to her baby. Women with HIV who breastfeed also can pass the virus to their babies.
Once in the blood, HIV attacks the immune system. As the immune system weakens, the body becomes less able to resist disease and other infections. AIDS is diagnosed when a person with HIV begins to develop diseases that the immune system normally would fight off, such as pneumonia, certain types of cancer, and harmful infections.
There are two types of HIV: 1) HIV-1 and 2) HIV-2. Most people with HIV in the United States have HIV-1.
Reasons for Getting Tested
It can take months or years before HIV infection might develop into AIDS. Unless you are tested, you may not know you are infected with HIV until you get sick. Knowing your HIV status is critical for your health and the health of others. Early diagnosis and treatment with anti-HIV drugs can help people with HIV infection stay healthy for a long time and can decrease the chance of passing the virus to others. Women with HIV also can take steps to avoid unintended pregnancy. Women with HIV should be in the best possible health if they become pregnant. Those who receive treatment during pregnancy can reduce the risk of passing the virus to their babies.
Who Should Be Tested?
HIV testing is a routine part of health care. The Centers for Disease Control and Prevention and the American College of Obstetricians and Gynecologists recommend that everyone aged 13–64 years be tested for HIV at least once in their lifetime. HIV testing also is recommended for women who are pregnant or who are thinking about becoming pregnant. Retesting is recommended each year if you have any of the following risk factors for HIV infection:
- Inject (shoot) illegal drugs
- Have a sex partner who is an injection drug user or is infected with HIV
- Exchange sex for drugs or money
- Have had a male sex partner who has had sex with men since your most recent HIV test
- Have had more than one sex partner since your most recent HIV test
You can be tested for HIV again at any time, even if you do not have risk factors. If you are older than 64 years and you have risk factors for HIV, annual retesting is recommended. It also is a good idea for you and your partner to be tested before starting a new sexual relationship.
How HIV Testing Is Done
HIV testing can be done at a health care provider’s office (such as an obstetrician–gynecologist’s or a primary care provider’s office). HIV tests also are given at special HIV clinics.
The recommended HIV screening test looks for the presence of HIV antibodies and a specific HIV antigen called p24 in a sample of your blood. Antibodies are made by the immune system in response to infection with HIV. An antigen is a part of the virus. The test can detect the p24 antigen about 3 weeks after you are exposed to HIV. It takes a few days to get the results of this test.
There also are “rapid” HIV screening tests. With a rapid HIV screening test, results are ready quickly, ideally within 1 hour. Your obstetrician–gynecologist or primary care provider may offer rapid testing. Rapid tests also may be available at health clinics, local health department testing offices, hospitals, and community centers.
Home HIV screening test kits are available that test either a sample of oral fluid or a sample of blood that you obtain by pricking your finger. It is important to use only those home tests that are approved by the U.S. Food and Drug Administration and to carefully read the information and instructions that come with the kit. You must perform the test correctly to get an accurate result. The test that uses oral fluid looks for the presence of HIV antibodies only. It takes 3–6 months for the body to make antibodies after exposure to HIV. Test results may be negative if you perform the test early in the course of infection.
A “reactive” or positive screening test result does not necessarily mean that you are infected with HIV. No matter what kind of screening test you have, a confirming test must be done if you have a reactive or positive screening test result. The confirming test looks for the genetic material of the virus in a sample of your blood. Results take about 2 weeks. If the confirming test result is positive, you are infected with HIV.
What Happens If HIV Is Diagnosed
A positive HIV test result means that you have the virus and that you can infect others if you have unprotected sex or share needles to inject drugs. A positive test result does not tell you whether you have AIDS or if you will get sick. If you are infected with HIV, you should see a health care provider, even if you do not feel sick. You may be referred to a health care provider or group of health care providers who specialize in caring for people infected with HIV. Many drug therapies are now available that can help people infected with HIV stay healthy for a long time. The earlier treatment is started, the better for your long-term health. Early treatment also reduces your risk of giving the virus to uninfected sex partners.
Your health care provider will report your positive test results (but not your name) to your state health department. This is done to keep track of how many people in the United States have HIV. You should tell all of your sexual partners and needle-sharing partners about your HIV status so that they can be tested and begin treatment if they are HIV positive. Some state health departments have laws that pertain to people infected with HIV. You can find out information about your state by going to
Pregnant Women and HIV Testing
If you are pregnant, you will be given a routine test for HIV as early as possible in your pregnancy. If you are at an increased risk of HIV infection, you should be retested in the third trimester of pregnancy. You are at increased risk if you have any of the following risk factors:
- Have been given a diagnosis of another sexually transmitted infection in the past year
- Inject drugs or have a sex partner who injects drugs
- Exchange sex for money or drugs
- Live in an area with high numbers of people infected with HIV
- Have a new or more than one sex partner during this pregnancy
- Have a sex partner who is HIV positive or at high risk of being HIV positive
If you are pregnant and infected with HIV, the virus can be passed to your baby. The good news is that treatment during pregnancy and treating the baby after delivery can greatly reduce the chance of this happening. Treatment during pregnancy also can help you stay healthy. Treatment includes the following steps:
- Take a combination of anti-HIV drugs during your pregnancy as prescribed.
- Have a cesarean delivery if lab tests show that your level of HIV is high.
- Take anti-HIV drugs during labor and delivery as needed.
- Give an anti-HIV drug to your baby after birth.
- Do not breastfeed (if you live in the United States).
By following these guidelines, about 99% of HIV-infected women will not pass HIV on to their babies.
If you were not tested for HIV during pregnancy, it is recommended that you have a rapid HIV test when you go into labor. If this result is positive, you will need to have a confirming HIV test. While you are waiting for these results, you can receive anti-HIV drugs during labor, and the baby can be given anti-HIV drugs in the first few days after delivery. These precautions can greatly decrease the risk of transmitting the virus to the baby if it turns out that you are HIV positive. If the confirming test result is positive, both you and your baby will need ongoing treatment and follow-up. You can be treated with anti-HIV drugs to protect your own health, and your baby will continue anti-HIV drug treatment to decrease the chance of becoming infected. If the confirming test result is negative, it means that neither you nor the baby has HIV and treatment does not need to be continued.
For More Information
If you have questions about HIV, AIDS, or HIV testing, the following links may be helpful:
- National HIV and STD Testing Resources
Offers general information about HIV and sexually transmitted infection testing and gives testing locations.
- Centers for Disease Control and Prevention HIV/AIDS Resources
Provides comprehensive information about HIV and AIDS.
Network of web sites providing information about the federal government’s HIV/AIDS programs; also includes a testing and care locator service as well as information about living with HIV.
Acquired Immunodeficiency Syndrome (AIDS): A group of signs and symptoms, usually of severe infections, occurring in a person whose immune system has been damaged by infection with human immunodeficiency virus (HIV).
Antibodies: Proteins in the blood produced in reaction to foreign substances, such as bacteria and viruses that cause infection.
Antigen: A substance, such as an infection-causing organism or a protein found on the surface of blood cells, that can induce an immune response and cause the production of an antibody.
Cesarean Delivery: Delivery of a baby through surgical incisions made in the mother’s abdomen and uterus.
Human Immunodeficiency Virus (HIV): A virus that attacks certain cells of the body’s immune system and causes acquired immunodeficiency syndrome (AIDS).
Immune System: The body’s natural defense system against foreign substances and invading organisms, such as bacteria that cause disease.
Screening Test: A test that looks for possible signs of disease in people who do not have signs or symptoms.