• Enzyme-Linked Immunosorbent Assay (ELISA) determines HIV antibodies' presence in blood or oral fluids. When people show HIV antibodies on two or more ELISA tests, they undergo an independent, highly specific supplemental test (most commonly, the Western Blot test) to validate ELISA's results (3).
• Western Blot: a highly specific supplemental test that detects the presence of HIV antibodies in the blood. The Western Blot test is less sensitive than the Elisa test but it hardly ever gives a false positive result; therefore, it is used for confirming the Elisa test.
• Rapid serum HIV antibody tests, saliva- and urine- based antibody tests, and home HIV antibody testing kits have been approved by the Food and Drug Administration (FDA) and are commercially available (3). The rapid HIV tests can be administered outside of a traditional laboratory setting and processed in as little as 20 minutes (4).
• HIV RNA tests are being used in research and healthcare settings to diagnose HIV infection very early after exposure, before antibodies are even formed (3). These tests look for bits of HIV RNA in the blood.

Benefits of HIV Testing

HIV testing is useful for:

HIV-infected people, who may be able to reduce their symptoms and increase their life spans through treatment, and can reduce their risk of transmitting HIV. HIV-negative people, who may learn how to reduce their risk of acquiring HIV. Researchers and healthcare workers seeking to learn more about the epidemiology of HIV infection and the mechanisms of HIV transmission (5).

Most HIV testing is combined with HIV risk reduction counseling and referral for HIV/AIDS treatment (if the person does have HIV). Counseling, Testing, and Referral (CTR), also known as Voluntary Counseling and Testing (VCT), is acknowledged around the world as an important and cost-effective strategy for getting people to change those behaviors that put them at risk for contracting HIV. Getting tested is also many people's first step on the way to getting treatment for HIV/AIDS (6, 7).

Increasing Access to HIV Testing

In the United States, many HIV-infected individuals do not get tested until late in their infections. As a result, they are already very sick when they first learn that they are HIV+. For example, of the 104,780 people who tested positive for HIV between 1994 and 1999, 41% developed AIDS within one year. (8) Additionally, many people who are tested do not return to learn their test results.

An emphasis on expanding access to testing and on providing prevention and care services for people infected with HIV can reduce new infections and lead to reductions in HIV-associated morbidity and mortality (8). Strategies to increase access to HIV testing include making HIV testing a routine part of medical care, and implementing new models for diagnosing HIV infections outside medical settings (4).

References:
1. San Francisco AIDS Foundation. AIDS 101: HIV Testing. Francisco AIDS Foundation, 1998. Retrieved on January 15, 2004 from http://www.sfaf.org/aids101/hiv_testing.html.

2. Institutes of Allergy and Infectious Diseases (NIAID). HIV Infection and AIDS: An Overview. National Institutes of Allergy and Infectious Diseases, National Institutes of Health, U.S. Department of Health and Human Services, October 2003. Retrieved on January 14, 2004 from http://www.niaid.nih.gov/factsheets/hivinf.htm.

3. Constantine, N. HIV Antibody Assays. HIV InSite Knowledge Base Chapter. San Francisco, CA: Center for HIV Information, University of California, San Francisco, 2001. Retrieved on December 1, 2003 from http://www.hivinsite.com/InSite.jsp?page=kb-02&doc=kb-02-02-01.

4. Centers for Disease Control and Prevention (CDC). Advancing HIV prevention: The science behind the new initiative. 2003. Retrieved on January 27, 2004 from http://www.cdc.gov/hiv/partners/ahp_science.htm.

5. Roland, M.E., Fine, R., and Volberding, P.A. HIV antibody testing: Indications and interpretations. HIV InSite Knowledge Base Chapter. San Francisco, CA: Center for HIV Information, University of California San Francisco, 1998. Retrieved on December 1, 2003 from http://hivinsite.ucsf.edu/InSite?page=kbr-07-01-04&doc=kb-03-01-02.

6. Centers for Disease Control and Prevention (CDC). Revised Guidelines for HIV Counseling, Testing, and Referral: Technical Expert Panel Review of CDC HIV Counseling, Testing, and Referral Guidelines, 2001. Retrieved on December 4, 2003 from http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5019a1.htm.

7. Family Health International (FHI). Fact Sheet: Voluntary Counseling and Testing for HIV, 2003. Retrieved on December 9, 2003 from http://www.fhi.org/en/hivaids/factsheets/vctforhiv.htm.

8. Centers for Disease Control and Prevention (CDC) . Advancing HIV prevention: New strategies for a changing epidemic – United States, 2003. MMWR 52(15): 329-332, 2003.