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HIV AIDS Myths and Facts Slideshow Pictures Take the HIV/AIDS Quiz AIDS Retrospective Slideshow Pictures

Medical Author:

Mary D. Nettleman, MD, MS, MACP

Mary D. Nettleman, MD, MS, MACP

Mary D. Nettleman, MD, MS, MACP is the Chair of the Department of Medicine at Michigan State University. She is a graduate of Vanderbilt Medical School, and completed her residency in Internal Medicine and a fellowship in Infectious Diseases at Indiana University.

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Medical Author:

Daniel Havlichek, MD

Medical Editor:

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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What is HIV?

HIV is short for human immunodeficiency virus. This is the virus that causes the acquired immunodeficiency syndrome or AIDS. HIV is a complicated virus that uses RNA, not DNA, as its genetic messenger. It replicates primarily in specialized cells of the body's immune system called CD4 lymphocytes. During HIV replication, the CD4 cells are destroyed. As more and more cells are killed, the body loses the ability to fight many infections. If the number of CD4 cells falls below 200 per cubic millimeter, or if some other special conditions occur, the person is defined as having AIDS. These special conditions include infections and cancers that take advantage of the way that HIV suppresses the immune system. Regardless of the CD4 count, people with HIV infection carry the virus and can spread it to others through unprotected sex or contact with blood or some other body fluids.

More than 1 million Americans are currently infected with HIV. Over 250,000 of these Americans are not aware that they are infected. The U.S. Centers for Disease Control and Prevention (CDC) estimates that more than 50,000 new infections with HIV occur each year. Thus, HIV testing is important to diagnose those who are newly infected, to identify previously unrecognized infections, and to relieve the minds of those who are not infected. HIV testing is also used to reduce the risk of transmission during blood transfusions and tissue transplantation.

The CDC recommends routine HIV testing of adolescent and adult patients in all health-care settings and of all pregnant women. Thus, HIV testing is considered part of routine medical practice, similar to tests that screen for other diseases. People who are at high risk for HIV should be tested at least annually. Sometimes, doctors request or require testing as part of evaluation and treatment for other conditions, such as women undergoing treatment with assisted reproductive technologies for infertility. There is increasing concern that not enough people are being tested. Events such as National HIV Testing Day have been used to raise awareness and increase participation in testing.

In some cases, HIV testing may be required by law. This occurs for blood that is used for transfusions, organ donors, and military personnel. States may select additional populations for mandatory testing, such as prisoners or newborns.