I need the information for a school project Acquired immune deficiency syndrome or acquired immunodeficiency syndrome (AIDS or Aids) is a collection of symptoms and infections resulting from the specific damage to the immune system caused by the human immunodeficiency virus (HIV) in humans,[1] and similar viruses in other species (SIV, FIV, etc.). The late stage of the condition leaves individuals susceptible to opportunistic infections and tumors. Although treatments for AIDS and HIV exist to decelerate the virus's progression, there is currently no known cure. HIV, et al., are transmitted through direct contact of a mucous membrane or the bloodstream with a bodily fluid containing HIV, such as blood, semen, vaginal fluid, preseminal fluid, and breast milk.[2][3] This transmission can come in the form of anal, vaginal or oral sex, blood transfusion, contaminated hypodermic needles, exchange between mother and baby during pregnancy, childbirth, or breastfeeding, or other exposure to one of the above bodily fluids.
Most researchers believe that HIV originated in sub-Saharan Africa during the twentieth century;[4] it is now a pandemic, with an estimated 33.2 million people now living with the disease worldwide.[5] As of January 2006, the Joint United Nations Programme on HIV/AIDS (UNAIDS) and the World Health Organization (WHO) estimate that AIDS has killed more than 25 million people since it was first recognized on June 5, 1981, making it one of the most destructive epidemics in recorded history. In 2005 alone, AIDS claimed an estimated 2.4鈥?.3 million lives, of which more than 570,000 were children.[6] A third of these deaths are occurring in sub-Saharan Africa, retarding economic growth and destroying human capital. Antiretroviral treatment reduces both the mortality and the morbidity of HIV infection, but routine access to antiretroviral medication is not available in all countries.[7] AIDS death toll in Africa may reach 90-100 million by 2025.[8][9]
HIV/AIDS stigma is more severe than that associated with other life-threatening conditions and extends beyond the disease itself to providers and even volunteers involved with the care of people living with HIV.
Contents [hide]
1 Infection by HIV
2 Diagnosis
2.1 WHO disease staging system for HIV infection and disease
2.2 CDC classification system for HIV infection
2.3 HIV test
3 Symptoms and complications
3.1 Major pulmonary illnesses
3.2 Major gastro-intestinal illnesses
3.3 Major neurological illnesses
3.4 Major HIV-associated malignancies
3.5 Other opportunistic infections
4 Transmission and prevention
4.1 Sexual contact
4.2 Exposure to infected body fluids
4.3 Mother-to-child transmission (MTCT)
5 Treatment
6 Epidemiology
7 Economic impact
8 Stigma
9 Origin of HIV
10 Alternative hypotheses
11 HIV and AIDS misconceptions
12 Notes and references
13 External links
Infection by HIV
For more details on this topic, see HIV.
Scanning electron micrograph of HIV-1 budding from cultured lymphocyte.AIDS is the most severe acceleration of infection with HIV. HIV is a retrovirus that primarily infects vital organs of the human immune system such as CD4+ T cells (a subset of T cells), macrophages and dendritic cells. It directly and indirectly destroys CD4+ T cells.[10] CD4+ T cells are required for the proper functioning of the immune system. When HIV kills CD4+ T cells so that there are fewer than 200 CD4+ T cells per microliter (碌L) of blood, cellular immunity is lost. In some countries, such as the United States, this leads to a diagnosis of AIDS. In other jurisdictions, such as in Canada, AIDS is only diagnosed when a person infected with HIV is diagnosed with one or more of several AIDS-related opportunistic infections or cancers.[11][12][13] Acute HIV infection progresses over time to clinical latent HIV infection and then to early symptomatic HIV infection and later to AIDS, which is identified either on the basis of the amount of CD4+ T cells in the blood, and/or the presence of certain infections, as noted above.
In the absence of antiretroviral therapy, the median time of progression from HIV infection to AIDS is nine to ten years, and the median survival time after developing AIDS is only 9.2 months.[14] However, the rate of clinical disease progression varies widely between individuals, from two weeks up to 20 years. Many factors affect the rate of progression. These include factors that influence the body's ability to defend against HIV such as the infected person's general immune function.[15][16] Older people have weaker immune systems, and therefore have a greater risk of rapid disease progression than younger people. Poor access to health care and the existence of coexisting infections such as tuberculosis also may predispose people to faster disease progression.[14][17][18] The infected person's genetic inheritance plays an important role and some people are resistant to certain strains of HIV. An example of this is people with the homozygous CCR5-螖32 variation are resistant to infection with certain strains of HIV.[19] HIV is genetically variable and exists as different strains, which cause different rates of clinical disease progression.[20][21][22] The use of highly active antiretroviral therapy prolongs both the median time of progression to AIDS and the median survival time.
Diagnosis
Since June 5, 1981, many definitions have been developed for epidemiological surveillance such as the Bangui definition and the 1994 expanded World Health Organization AIDS case definition. However, clinical staging of patients was not an intended use for these systems as they are neither sensitive, nor specific. In developing countries, the World Health Organization staging system for HIV infection and disease, using clinical and laboratory data, is used and in developed countries, the Centers for Disease Control (CDC) Classification System is used.
WHO disease staging system for HIV infection and disease
Main article: WHO Disease Staging System for HIV Infection and Disease
In 1990, the World Health Organization (WHO) grouped these infections and conditions together by introducing a staging system for patients infected with HIV-1.[23] An update took place in September 2005. Most of these conditions are opportunistic infections that are easily treatable in healthy people.
Stage I: HIV infection is asymptomatic and not categorized as AIDS
Stage II: includes minor mucocutaneous manifestations and recurrent upper respiratory tract infections
Stage III: includes unexplained chronic diarrhea for longer than a month, severe bacterial infections and pulmonary tuberculosis
Stage IV: includes toxoplasmosis of the brain, candidiasis of the esophagus, trachea, bronchi or lungs and Kaposi's sarcoma; these diseases are indicators of AIDS.
CDC classification system for HIV infection
Main article: CDC Classification System for HIV Infection
In the beginning, the Centers for Disease Control and Prevention (CDC) did not have an official name for the disease, often referring to it by way of the diseases that were associated with it, for example, lymphadenopathy, the disease after which the discoverers of HIV originally named the virus.[24][25] They also used Kaposi's Sarcoma and Opportunistic Infections, the name by which a task force had been set up in 1981.[26] In the general press, the term GRID, which stood for Gay-related immune deficiency, had been coined.[27] However, after determining that AIDS was not isolated to the homosexual community,[26] the term GRID became misleading and AIDS was introduced at a meeting in July 1982.[28] By September 1982 the CDC started using the name AIDS, and properly defined the illness.[29] In 1993, the CDC expanded their definition of AIDS to include all HIV positive people with a CD4+ T cell count below 200 per 碌L of blood or 14% of all lymphocytes.[30] The majority of new AIDS cases in developed countries use either this definition or the pre-1993 CDC definition. The AIDS diagnosis still stands even if, after treatment, the CD4+ T cell count rises to above 200 per 碌L of blood or other AIDS-defining illnesses are cured.
HIV test
Main article: HIV test
Many people are unaware that they are infected with HIV.[31] Less than 1% of the sexually active urban population in Africa has been tested, and this proportion is even lower in rural populations. Furthermore, only 0.5% of pregnant women attending urban health facilities are counseled, tested or receive their test results. Again, this proportion is even lower in rural health facilities.[31] Therefore, donor blood and blood products used in medicine and medical research are screened for HIV. Typical HIV tests, including the HIV enzyme immunoassay and the Western blot assay, detect HIV antibodies in serum, plasma, oral fluid, dried blood spot or urine of patients. However, the window period (the time between initial infection and the development of detectable antibodies against the infection) can vary. This is why it can take 3鈥? months to seroconvert and test positive. Commercially available tests to detect other HIV antigens, HIV-RNA, and HIV-DNA in order to detect HIV infection prior to the development of detectable antibodies are available. For the diagnosis of HIV infection these assays are not specifically approved, but are nonetheless routinely used in developed countries.
Symptoms and complications
A generalized graph of the relationship between HIV copies (viral load) and CD4 counts over the average course of untreated HIV infection; any particular individual's disease course may vary considerably.
CD4+ T Lymphocyte count (cells/mm鲁)
HIV RNA copies per mL of plasmaThe symptoms of AIDS are primarily the result of conditions that do not normally develop in individuals with healthy immune systems. Most of these conditions are infections About 25 million apparently. |
