AIDS (Acquired Immune Deficiency Syndrome) is the final and most serious stage of HIV disease, which causes severe damage to the immune system.
According to the Centers for Disease Control and Prevention, AIDS begins when a person with HIV infection has a CD4 cell count below 200. CD4 cells are also called "T-cells" or "helper cells"; they are a type of immune cell. AIDS is also defined by numerous opportunistic infections and cancers that occur in the presence of HIV infection.
Alternative Names
Acquired immune deficiency syndrome
Causes, incidence, and risk factors
AIDS is the fifth leading cause of death among persons between ages 25 and 44 in the United States, down from number one in 1995. About 25 million people worldwide have died from this infection since the start of the epidemic, and 40.3 million people are currently living with HIV/AIDS globally
Human immunodeficiency virus (HIV) causes AIDS. The virus attacks the immune system and leaves the body vulnerable to a variety of life-threatening infections and cancers.
Common bacteria, yeast, parasites, and viruses that ordinarily do not cause serious disease in people with healthy immune systems can cause fatal illnesses in people with AIDS.
HIV has been found in saliva, tears, nervous system tissue and spinal fluid, blood, semen (including pre-seminal fluid), vaginal fluid, and breast milk. However, only blood, semen, vaginal secretions, and breast milk generally transmit infection to others.
Transmission of the virus occurs:
Through sexual contact -- including oral, vaginal, and anal sex
Through blood -- via blood transfusions (now extremely rare in the U.S) or needle sharing
From mother to child -- a pregnant woman can transmit the virus to her fetus through their shared blood circulation, or a nursing mother can transmit it to her baby in her milk
Other transmission methods are rare and include accidental needle injury, artificial insemination with donated semen, and organ transplants.
HIV infection is not spread by casual contact such as hugging, by touching items previously touched by a person infected with the virus, during participation in sports, or by mosquitoes.
It is not transmitted to a person who DONATES blood or organs. Those who donate organs are not in direct contact with those who receive them. Likewise, a person who donates blood is not in contact with the person receiving it.
HIV infection (5 images)(Doctor-Reviewed information)
HIV infection is a disease caused by the human immunodeficiency virus (HIV. The condition gradually destroys the immune system, which makes it harder for the body to fight off infections. This article provides a general overview. For more detailed information, see: AIDS; Acute HIV infection; Asymptomatic HIV infection; Early symptomatic HIV infection. Reviewer: Kenneth M. Wener, M.D., Department of Infectious Diseases, Lahey Clinic, Burlington, MA. Review provided by VeriMed Healthcare Network.Date: 11/01/2007
Early symptomatic HIV infection (10 images)(Doctor-Reviewed information)
Early symptomatic HIV infection is a stage of infection with the human immunodeficiency virus when symptoms are present but AIDS has not yet developed. See also: Acute HIV infection; Asymptomatic HIV infection; HIV infection. Reviewer: Kenneth M. Wender, M.D., Dept. of Infectious Diseases, Lahey Clinic, Burlington, MA. Review provided by VeriMed Healthcare Network.Date: 11/01/2007
Acute HIV infection (4 images)(Doctor-Reviewed information)
Acute HIV infection is caused by the human immunodeficiency virus (HIV), a virus that gradually destroys the immune system. Reviewer: Kenneth M. Wener, M.D., Department of Infectious Diseases, Lahey Clinic, Burlington, MA. Review provided by VeriMed Healthcare Network.Date: 11/01/2007
HIV ELISA/Western blot (1 image)(Doctor-Reviewed information)
HIV ELISA/Western blot is a set of blood tests used in the diagnosis of chronic infection with human immunodeficiency virus (HIV. The HIV ELISA is a screening test for the diagnosis of HIV infection. If this test is positive, it must be confirmed with a second test called the Western blot, which is more specific and will confirm if someone is truly HIV positive (there are other conditions that may inaccurately produce a positive ELISA test result, including lupus, Lyme disease, and syphilis. Reviewer: Monica Gandhi MD, MPH, Assistant Professor, Division of Infectious Diseases, UCSF, San Francisco, CA. Review provided by VeriMed Healthcare Network.Date: 03/06/2006
Kaposi’s sarcoma (6 images)(Doctor-Reviewed information)
Kaposi's sarcoma is a cancerous tumor of the connective tissue, and is often associated with AIDS. Reviewer: Rita Nanda, MD, Department of Medicine, Section of Hematology/Oncology, University of Chicago Medical Center, Chicago, IL. Review provided by VeriMed Healthcare Network.Date: 09/11/2006
Pneumocystis carinii pneumonia (3 images)(Doctor-Reviewed information)
Pneumocystis carinii pneumonia (PCP) is a fungal infection of the lungs. Reviewer: Kenneth M. Wener, M.D., Department of Infectious Diseases, Lahey Clinic, Burlington, MA. Review provided by VeriMed Healthcare Network.Date: 11/01/2007
Pneumonia in immunocompromised host (4 images)(Doctor-Reviewed information)
Pneumonia in an immunocompromised host describes a lung infection that occurs in a person whose ability to fight infection is greatly reduced. See also: Hospital-acquired pneumonia; Mycoplasma pneumonia; Pneumonia - cytomegalovirus; Pneumonia; Viral pneumonia; Walking pneumonia. Reviewer: D. Scott Smith, MD., MSc., DTM., Prof. Medical Microbiology & Immunology, Dept. of Human Biology, Stanford Univ. School of Medicine, Stanford, CA. Review provided by VeriMed Healthcare Network. Date: 08/06/2007
Immunodeficiency disorders (1 image)(Doctor-Reviewed information)
Immunodeficiency disorders occur when the body's immune response is reduced or absent. See also: Autoimmune disorders Reviewer: Donald Accetta, MD, MPH, President, Allergy & Asthma Care, PC, Taunton, MA. Review provided by VeriMed Healthcare NetworDate: 05/30/2007
CMV - immunocompromised host (2 images)(Doctor-Reviewed information)
Cytomegalovirus (CMV) is a member of a group of herpes-type viruses that can cause disease in different parts of the body in persons with weakened immune systems. Reviewer: Kenneth M. Wener, M.D., Department of Infectious Diseases, Lahey Clinic, Burlington, MA. Review provided by VeriMed Healthcare Network.Date: 11/01/2007
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