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1、AIDSAcquired immunodeficiency syndrome (AIDS)Classification and external resourcesThe Red ribbon is a symbol for solidarity with HIV-positive people and those living with AIDS.ICD-10B24.ICD-9042DiseasesDB5938MedlinePlus000594eMedicineemerg/253MeSHD000163List of abbreviations used in this articleAIDS
2、: Acquired immune deficiency syndromeHIV: Human immunodeficiency virusCD4+: CD4+ T helper cellsCCR5: Chemokine (C-C motif) receptor 5CDC: Centers for Disease Control and PreventionWHO: World Health OrganizationPCP: Pneumocystis pneumoniaTB: TuberculosisMTCT: Mother-to-child transmissionHAART: Highly
3、 active antiretroviral therapySTI/STD: Sexually transmitted infection/diseaseAcquired immune deficiency syndrome or acquired immunodeficiency syndrome (AIDS) is a disease of the human immune system caused by the human immunodeficiency virus (HIV).123This condition progressively reduces the effective
4、ness of the immune system and leaves individuals susceptible to opportunistic infections and tumors. HIV is 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.45This tra
5、nsmission can involve 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.AIDS is now a pandemic.6 In 2007, it was estimated that 33.2millio
6、n people lived with the disease worldwide, and that AIDS had killed an estimated 2.1million people, including 330,000 children.7 Over three-quarters of these deaths occurred in sub-Saharan Africa,7 retarding economic growth and destroying human capital.8Genetic research indicates that HIV originated
7、 in west-central Africa during the late nineteenth or early twentieth century.910 AIDS was first recognized by the U.S. Centers for Disease Control and Prevention in 1981 and its cause, HIV, identified in the early 1980s.11Although treatments for AIDS and HIV can slow the course of the disease, ther
8、e is currently no vaccine or cure. Antiretroviral treatment reduces both the mortality and the morbidity of HIV infection, but these drugs are expensive and routine access to antiretroviral medication is not available in all countries.12 Due to the difficulty in treating HIV infection, preventing in
9、fection is a key aim in controlling the AIDS epidemic, with health organizations promoting safe sex and needle-exchange programmes in attempts to slow the spread of the virus.SymptomsA generalized graph of the relationship between HIV copies (viral load) and CD4 counts over the average course of unt
10、reated HIV infection; any particular individuals disease course may vary considerably. CD4+ T Lymphocyte count (cells/mm) 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
11、conditions are infections caused by bacteria, viruses, fungi and parasites that are normally controlled by the elements of the immune system that HIV damages.Opportunistic infections are common in people with AIDS.13 HIV affects nearly every organ system.People with AIDS also have an increased risk
12、of developing various cancers such as Kaposis sarcoma, cervical cancer and cancers of the immune system known as lymphomas. Additionally, people with AIDS often have systemic symptoms of infection like fevers, sweats (particularly at night), swollen glands, chills, weakness, and weight loss.1415 The
13、 specific opportunistic infections that AIDS patients develop depend in part on the prevalence of these infections in the geographic area in which the patient lives.Main symptoms of AIDS.Pulmonary infectionsX-ray of Pneumocystis pneumonia (PCP). There is increased white (opacity) in the lower lungs
14、on both sides, characteristic of PCPPneumocystis pneumonia (originally known as Pneumocystis carinii pneumonia, and still abbreviated as PCP, which now stands for Pneumocystis pneumonia) is relatively rare in healthy, immunocompetent people, but common among HIV-infected individuals. It is caused by
15、 Pneumocystis jirovecii.Before the advent of effective diagnosis, treatment and routine prophylaxis in Western countries, it was a common immediate cause of death. In developing countries, it is still one of the first indications of AIDS in untested individuals, although it does not generally occur
16、unless the CD4 count is less than 200 cells per L of blood.16Tuberculosis (TB) is unique among infections associated with HIV because it is transmissible to immunocompetent people via the respiratory route, is easily treatable once identified, may occur in early-stage HIV disease, and is preventable with drug therapy. How
