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Frequently Asked Questions (FAQs) About HIV and AIDS (FAQ Home)

HIV Testing

Are antibody tests as accurate on young children as adults? Return to top

Theoretically, the accuracy of testing for infants should be the same as for adults and children. However, diagnosis is hampered by the fact that infants born to HIV-infected mothers can test positive for antibodies passively acquired from their mothers for as long as 15 months, although only a portion of them (current estimates range from 30 percent to 50 percent) are actually infected with HIV. In this case, a positive antibody test alone is not sufficient to confirm that the infant is infected with HIV.

Are there other tests available? Return to top

The EIA (enzyme immunoassay) is the standard screening test used to detect the presence of antibodies to HIV. The EIA should be used with a confirmatory test such as the Western blot. Tests that detect other signs of HIV are available for special purposes, such as for additional testing of the blood supply and conducting research. Because some tests are expensive or require sophisticated equipment and specialized training, their use is limited. In addition to the EIA, other tests now available include:

  • Radioimmunoprecipitation assay (RIPA): A confirmatory blood test that may be used when antibody levels are very low or difficult to detect or when Western blot test results are uncertain. An expensive test, the RIPA requires time and expertise to perform.

  • Rapid latex agglutination assay: A simplified, inexpensive blood test that may prove useful in medically disadvantaged areas where there is a high prevalence of HIV infection.

  • Dot-blot immunobinding assay: A rapid-screening blood test that is cost-effective and that may become an alternative to conventional EIA and Western blot testing.

  • p24 antigen capture assay: Also known as the HIV-1 antigen capture assay. This blood test was added as an interim measure by the Food and Drug Administration (FDA) in 1996 to HIV-antibody testing to protect the blood supply further until other tests become available to detect early HIV infection before antibodies are fully developed. Because some activity of p24 antigen is unpredictable, this test is not useful for helping people find out if they have HIV.

  • Polymerase chain reaction (PCR): A specialized blood test that looks for HIV genetic information. Although expensive and labor-intensive, the test can detect the virus even in someone only recently infected. To further protect the blood supply, the FDA has indicated that the development and implementation of tests for HIV genetic material such as PCR is warranted.

Are there tests that don't involve drawing blood, like urine or oral fluids? Return to top


HIV antibodies can be detected in the urine through a screening EIA test. Urine samples repeatedly reactive to the EIA may be further tested with a supplemental urine Western blot test. These FDA-approved tests must be ordered by a physician, and results are reported to the ordering physician or someone under his or her supervision.

Because urine collection is not invasive, it offers an alternative for patients reluctant to have blood drawn. Urine testing also minimizes laboratory worker risk for HIV exposure because it involves no needles or lancets and because urine has not been shown to transmit HIV.

Urine testing for HIV antibodies is not as sensitive or specific as blood testing and is not to be used for screening potential blood donors. Patients must sign or initial a Subject Information Brochure before being tested.

Orasure© is currently the only FDA approved oral fluid test. This product uses a device to collect oral fluids from inside the mouth. The sample is then tested for HIV antibodies using an EIA test and if repeatedly reactive, may then be tested with a supplemental Western Blot test.

Oral fluid tests are offered at many clinics and HIV testing locations. Contact the location near you to find out if this test is available.

How long after a possible exposure should I wait to get tested for HIV? Return to top

The tests commonly used to detect HIV infection actually look for antibodies produced by your body to fight HIV. Most people will develop detectable antibodies within 3 months after infection, the average being 25 days. In rare cases, it can take up to 6 months. For this reason, the CDC currently recommends testing 6 months after the last possible exposure (unprotected vaginal, anal, or oral sex or sharing needles). It would be extremely rare to take longer than 6 months to develop detectable antibodies. It is important, during the 6 months between exposure and the test, to protect yourself and others from further possible exposures to HIV.

If you have personal issues concerning HIV and AIDS and wish to speak to an information specialist to discuss risk factors and how to prevent HIV transmission, you may call the CDC National STD and AIDS Hotline 24 hours a day, 365 days a year at:

  • 1-800-342-AIDS (1-800-342-2437)
  • 1-800-AIDS-TTY (1-800-243-7889) TTY
  • 1-800-344-SIDA (1-800-344-7432) Spanish

If I test HIV negative, does that mean that my partner is HIV negative also? Return to top

No. Your HIV test result reveals only your HIV status. Your negative test result does not tell you whether your partner has HIV.

HIV is not necessarily transmitted every time there is an exposure. Therefore, your taking an HIV test should not be seen as a method to find out if your partner is infected. Testing should never take the place of protecting yourself from HIV infection. If your behaviors are putting you at risk for exposure to HIV, it is important to reduce your risks.

What are rapid HIV tests? Return to top

A rapid test for detecting antibody to HIV is a screening test that produces very quick results, usually in 5 to 30 minutes. In comparison, results from the commonly used HIV antibody screening test, the EIA (enzyme immunoassay), are not available for 1-2 weeks.

The only rapid HIV test currently licensed by the Food and Drug Administration for use in the United States in the Single Use Diagnostic System for HIV-1 (SUDS), manufactured by Murex. The availability of rapid HIV tests may differ from one place to another. The rapid HIV test is considered to be just as accurate as the EIA.

Both the rapid test and the EIA look for the presence of antibodies to HIV. As is true for all screening tests (including the EIA), a reactive rapid HIV test result must be confirmed before a diagnosis of infection can be given.

What if I test positive for HIV? Return to top

If you test positive for HIV, the sooner you take steps to protect your health, the better. Early medical treatment and a healthy lifestyle can help you stay well. Prompt medical care may delay the onset of AIDS and prevent some life-threatening conditions. There are a number of important steps you can take immediately to protect your health:

  • See a doctor, even if you do not feel sick. Try to find a doctor who has experience treating HIV. There are now many drugs to treat HIV infection and help you maintain your health. It is never too early to start thinking about treatment possibilities.
  • Have a TB (tuberculosis) test done. You may be infected with TB and not know it. Undetected TB can cause serious illness, but it can be successfully treated if caught early.
  • Smoking cigarettes, drinking too much alcohol, or using illegal drugs (such as cocaine) can weaken your immune system. There are programs available that can help you reduce or stop using these substances.
There is much you can do to stay healthy. Learn all that you can about maintaining good health.

If you have personal issues concerning HIV and AIDS and wish to speak to an information specialist to discuss risk factors and how to prevent HIV transmission, you may call the CDC National STD and AIDS Hotline 24 hours a day, 365 days a year at:

  • 1-800-342-AIDS (1-800-342-2437)
  • 1-800-AIDS-TTY (1-800-243-7889) TTY
  • 1-800-344-SIDA (1-800-344-7432) Spanish

What is an HIV antibody test? Return to top

When HIV enters the bloodstream, it begins to attack certain white blood cells called T4 lymphocyte cells (helper cells). The immune system then produces antibodies to fight off the infection. Although these antibodies are ineffective in destroying HIV, their presence in the blood is used to confirm HIV infection.

Two types of tests are commonly used to detect HIV infection. The most commonly used initial test is a type of enzyme immune assay (EIA) called enzyme-linked immunosorbent assay (ELISA). This test looks for the presence of HIV antibodies; it does not test for the virus itself.

If the ELISA test results are reactive, the test is repeated on the same blood sample. If the sample is repeatedly reactive, the results are "confirmed" using a second antibody screening test such as the Western blot. This more specific (and more expensive) second test can differentiate between HIV antibodies and other antibodies that react to the ELISA that cause positive results even when the person is not actually infected with HIV. Although false positive ELISA results are uncommon, they can occur when the test mistakes other antibodies that the body has manufactured to fight foreign substances for those produced to fight HIV. A repeatedly reactive result from the ELISA, confirmed by the Western blot test, indicates the presence of HIV antibodies; the individual tested is considered to be infected.

Where can I get tested for HIV infection? (Download PDF Version) Return to top

Many places provide testing for HIV infection. Common testing locations include local health departments, offices of private doctors, hospitals, and sites specifically set up to provide HIV testing.

It is important to seek testing at a place that also provides counseling about HIV and AIDS. Counselors can answer any questions you might have about risky behavior and ways you can protect yourself and others in the future. In addition, they can help you understand the meaning of the test results and describe what AIDS-related resources are available in the local area.

The CDC National STD and AIDS Hotline can answer questions about testing and can refer you to testing sites in your area or go to the HIV Testing Sites database for a list of sites in your area. You may call the CDC National STD and AIDS Hotline 24 hours a day, 365 days a year at:

  • 1-800-342-AIDS (1-800-342-2437)
  • 1-800-AIDS-TTY (1-800-243-7889) TTY
  • 1-800-344-SIDA (1-800-344-7432) Spanish

Consumer-controlled test kits (popularly known as "home test kits") were first licensed in 1997. Although home HIV tests are sometimes advertised through the Internet, currently only the Home Access test is approved by the Food and Drug Administration. (The accuracy of home test kits other than Home Access cannot be verified.) The Home Access test kit can be found at most local drug stores. The testing procedure involves pricking your finger with a special device, placing drops of blood on a specially treated card, then mailing the card in to be tested at a licensed laboratory. Customers are given an identification number to use when phoning for the test results. Callers may speak to a counselor before taking the test, while waiting for the test result, and when getting the result.

Who should get an HIV test? Return to top

Counseling and early diagnosis of HIV infection are recommended for: persons attending sexually transmitted disease and drug treatment clinics, the spouses and sex or needle-sharing partners of IV drug users, women of childbearing age who are at risk of infection, tuberculosis patients, and selected patients who received transfusions of blood or blood components between early 1978 and mid-1985. In addition, persons considering marriage should have ready access to information and educational materials about AIDS and voluntary counseling and testing. The President also has mandated the screening of immigrants entering the United States, foreign service personnel, and inmates of Federal prisons.

Why is CDC recommending that all pregnant women be tested for HIV? Return to top

There are now medical therapies available to lower the chance of an HIV-infected pregnant woman passing HIV to her infant before, during, or after birth. ZDV (zidovudine, also known as AZT or Retrovir) is the only drug which has been proven to reduce perinatal transmission. In 1998, the U.S. Public Health Services released updated recommendations for offering antiretroviral therapy to HIV positive pregnant women.

HIV testing and counseling provides an opportunity for infected women to find out they are infected and to gain access to medical treatment that may help to delay disease progression. For women who are not infected, HIV counseling provides an opportunity to learn important prevention information to reduce the possibility of future exposures.

Why isn't HIV testing mandatory in the United States? Return to top

The PHS program to prevent the spread of HIV/AIDS is based on testing, counseling, and education. Through these three activities, individuals who have engaged in high-risk behavior are encouraged to seek voluntary HIV antibody testing for themselves and their partners.

Except in the military and some institutional settings, mandatory HIV testing has not been implemented in the United States. The Public Health Service (PHS) does not recommend mandatory HIV testing of individuals for several reasons. Although tests for HIV are highly accurate, persons who have recently been infected with HIV can test HIV negative. This situation may create a false sense of security, making people less willing to practice the protective behaviors necessary to prevent HIV transmission to other persons. Widespread mandatory testing is expensive and difficult to manage and has the potential to violate the civil rights and confidentiality of infected persons.