Overview of HIV/AIDS

Human immunodeficiency virus (HIV) is one of two retroviruses (HIV-1, which is more prevalent, and HIV-2). A retrovirus is a virus that stores its genetic information in RNA, rather than in DNA, which is characteristic of ordinary viruses.

As of 2012, the World Health Organization (WHO) estimates that 35.3 million people worldwide were living with HIV and that the virus had caused about 36 million deaths.

HIV is transmitted through body fluids such as blood, semen, vaginal secretions, and breast milk. It can be present in any of the body's fluids. It is not transmitted casually, but through intimate contact such as heterosexual and homosexual intercourse and sharing needles. High-risk behaviors such as intravenous drug abuse and unprotected sex (particularly with multiple partners) should be avoided.

HIV attacks and destroys components of the body's immune system, particularly lymphocytes (a type of white blood cell) known as T cells. HIV infection slowly attacks and ultimately destroys the immune system, leaving the body susceptible to many diseases and disorders, including infections and cancers.

Soon after being infected with HIV, a person may experience mononucleosis-like symptoms, such as fevers, chills, sore throat, fatigue, muscle aches, swollen lymph nodes, and a skin rash. Typically, the patient appears to recover and symptoms often disappear for a time. In reality, the virus remains latent in the body, often for years. During this period, the virus multiplies and begins to affect the body in various ways. Eventually, as the body weakens and the virus increases in numbers, a variety of disorders emerge. These range from swollen lymph nodes, yeast infections, fatigue, night sweats, diarrhea, cancers such as Kaposi's sarcoma, central nervous system disorders, gastrointestinal disorders, and mental derangement.

HIV can be detected through laboratory tests such as the ELISA test and the Western blot test. Such testing is critically important, as early detection and treatment may delay the progression of HIV to acquired immune deficiency syndrome (AIDS).

The Centers for Disease Control and Prevention (CDC) defines the progression from HIV to AIDS as either:

  • infection with HIV and a T4 cell count of less than 200, or
  • infection with HIV and one of 26 opportunistic infections or neoplasms. An opportunistic infection is a normally benign microbe or virus that causes disease in people with a suppressed immune system.

Generally, an absolute T cell count of less than 500 (less than 200 particularly) is associated with many of the disorders resulting from HIV infection and AIDS.

Western treatment of HIV includes potent combinations of two or more antiretroviral drugs to fight HIV infection and other drugs to treat specific opportunistic infections or diseases. Drugs are sometimes used prophylactically to prevent opportunist infections. Antiretroviral drugs have increased the life span of many patients with AIDS. Treatment is crucial to survival and without treatment all cases of HIV will progress to AIDS.

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 01 Jan 2001

Last Modified: 22 Sep 2015