Human Immunodeficiency Virus (HIV)

  • Medical Author:
    Eric S. Daar, MD

    Dr. Daar received his undergraduate degree from UCLA and medical degree from Georgetown University School of Medicine. He completed an internship and residency in internal medicine at Cedars-Sinai Medical Center and his clinical and research fellowship in infectious diseases at Cedars-Sinai Medical Center and UCLA.

  • Medical Editor: Jay W. Marks, MD
    Jay W. Marks, MD

    Jay W. Marks, MD

    Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

HIV/AIDS Myths and Facts

Quick GuideHIV AIDS Pictures Slideshow: Myths and Facts on Symptoms and Treatments

HIV AIDS Pictures Slideshow: Myths and Facts on Symptoms and Treatments

What is the history of HIV, and when was HIV discovered?

The history of the human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS) dates back to 1981, when homosexual men with symptoms and signs of a disease that now are considered typical of AIDS were first described in Los Angeles and New York. The men had an unusual type of lung infection (pneumonia) called Pneumocystis carinii (now known as Pneumocystis jiroveci) pneumonia (PCP) and rare skin tumors called Kaposi's sarcomas. The patients were noted to have a severe reduction in a type of cell in the blood (CD4 cells) that is an important part of the immune system. These cells, often referred to as T cells, help the body fight infections. Shortly thereafter, this disease was recognized throughout the United States, Western Europe, and Africa. In 1983, researchers in the United States and France described the virus that causes AIDS, now known as HIV, belonging to the group of viruses called retroviruses. While HIV infection is required to develop AIDS, the actual definition of AIDS is the development of a low CD4 cell count (<200 cells/mm3) or any one of a long list of complications of HIV infection ranging from a variety of so-called "opportunistic infections," cancers, neurologic symptoms, and wasting syndromes.

What tests are used in the diagnosis of HIV?

In 1985, a blood test became available that measures antibodies to HIV that are the body's immune response to the HIV. The test that for decades had been most commonly used for diagnosing infection with HIV was referred to as an ELISA. If the ELISA found HIV antibodies, the results needed to be confirmed, typically by a test called a Western blot. Recently, tests have become available to look for these same antibodies in saliva, some providing results within one to 20 minutes of testing. As a result, the FDA has approved home HIV antibody testing that is self-administered using saliva. Antibodies to HIV typically develop within several weeks of infection. During this interval, patients have virus in their body but will test negative by the standard antibody test, the so-called "window period." In this setting, the diagnosis can be made if a test is used that actually detects the presence of virus in the blood rather than the antibodies, such as tests for HIV RNA or p24 antigen. A relatively new test has been approved that measures both HIV antibodies and p24 antigen, shrinking the duration of the window period from infection to diagnosis. New federal guidelines now recommend that HIV screening tests be performed with these assays and, if they are positive, that a confirmatory antibody test be performed that will determine if the patient has HIV-1, the most common form of HIV circulating around the world, or HIV-2, a related virus that occurs most frequently in Western Africa. If the confirmatory antibody test is negative, then there remains the possibility that the original test detected viral p24 antigen and not antibodies. Therefore, the recommendations are that if the confirmatory antibody test is negative a test for HIV RNA, a test for the presence of virus be performed. If the antibody is negative and the viral test is positive, the patient is diagnosed with acute or primary HIV infection and will develop a positive antibody test over the ensuing weeks.

Although the tests for detecting HIV infection continue to improve, they still require that people volunteer for testing. It is estimated that approximately 15% of those infected with HIV in the United States are unaware of their infection because they have never been tested. In order to decrease the number that are unaware of their HIV infection status, in 2006, the Centers for Disease Control and Prevention recommended that all people between 13 and 64 years of age be provided HIV testing whenever they encounter the health-care system for any reason. In addition, resources are available to facilitate people finding local HIV testing centers (http://www.hivtest.org).

Medically Reviewed by a Doctor on 12/17/2015

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