Acquired Immune Deficiency Syndrome (AIDS), is a diseases or conditions that result from suppression of the immune system, related to infection with the human immuno deficiency virus (HIV). A person infected with HIV gradually loses immune function The human immuno deficiency virus (HIV) causes AIDS.
Infection with HIV does not necessarily mean that a person has AIDS, although people who are HIV-positive are often mistakenly said to have AIDS. In 1997 an estimated 30.6 million people worldwide were living with HIV or AIDS—29.5 million adults and 1.1 million children.
The progression from the point of HIV infection to the clinical diseases that define AIDS may take six to ten years or more, ihe person eventually enters the advanced AIDS phase.
Death from AIDS is generally due not to HIV infection itself, but to opportunistic infections that occur when the immune system can no longer protect the body against agents normally found in the environment.
HIV is spread through the exchange of body fluids, primarily semen, blood, and blood products. HIV is also spread by any sharing of needles or syringes that result in direct exposure to the blood of an infected individual. Although only about 25 to 35 percent of babies born by HIV-infected mothers worldwide actually become infected, this mode of transmission accounts for 90 percent of all cases of AIDS in children. There is also no risk of contracting HIV infection while donating blood.
HIV does not survive well when exposed to the environment. Researchers have recently identified a protein in saliva, known as secretory leukocyte protease inhibitor (SLPI) that prevents HIV from infecting white blood cells.
In the United States, HIV infection was initially concentrated in the homosexual community—where widespread transmission occurred because of high-risk sexual behavior—and in people with hemophilia and other individuals receiving blood products.
The major strain of HIV in the United States, Europe, and central Africa is known as HIV-1. In western Africa, AIDS is also caused by HIV-2, a strain of HIV closely related to HIV-1. Even in the case of HIV-2, spread outside Africa is rare. In 1985 the first blood test for HIV, developed by the research group led by Robert Gallo, was approved for use in blood banks. This test can detect whether a person’s blood contains antibodies against HIV, an indication of exposure to the virus.
However, for about four to eight weeks after exposure to HIV, an individual will continue to test negative for HIV infection because the immune system has not had enough time to make antibodies against HIV. This test can detect HIV antigens—proteins produced by the virus itself. Due to the major differences in the protein components of HIV-1 and HIV-2, separate tests were developed to detect these two related viruses.
Antiviral drugs that attack HIV exploit vulnerable spots in the viral replication cycle. One class of anti-HIV drugs, known as nucleosides, are all RT inhibitors. A second problem is the emergence of drug-resistant forms of HIV in people receiving these drugs. Because HIV replicates rapidly and mutates frequently during the earliest period of infection, an HIV-infected person carries many different strains of HIV, some of which may be drug-resistant. Although RT inhibitors were never considered a cure for HIV infection, it was hoped that they would slow the progression of AIDS, and AZT has been shown effective in reducing HIV transmission from pregnant women to their babies. Many people consider HIV infection and AIDS to be completely preventable because the routes of HIV transmission are so well known. Prevention programs that identify HIV-infected individuals and notify their sexual partners, as well as programs that promote HIV testing at the time of marriage or pregnancy, have been criticized for invading personal privacy.
In 1990 HIV-infected people were included in the Americans with Disabilities Act, making discrimination against peopple with AIDS for jobs, housing, and other social benefits illegal. The lack of effective vaccines and antiviral drugs for AIDS has spurred speculation that the funding for AIDS research is insufficient.