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HIV/AIDS

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Human immunodeficiency virus infection and acquired immune deficiency syndrome ( HIV/AIDS ) is a spectrum of conditions caused by infection with the human immunodeficiency virus (HIV). Following initial infection a person may not notice any symptoms, or may experience a brief period of influenza-like illness. Typically, this is followed by a prolonged period with no symptoms. If the infection progresses, it interferes more with the immune system, increasing the risk of developing common infections such as tuberculosis, as well as other opportunistic infections, and tumors which are otherwise rare in people who have normal immune function. These late symptoms of infection are referred to as acquired immunodeficiency syndrome (AIDS). This stage is often also associated with unintended weight loss. HIV is spread primarily by unprotected sex (including anal and oral sex), contaminated blood transfusions, hypodermic needles, and from mother to child during pregnancy, delivery, or breastf...

Signs and symptoms

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There are three main stages of HIV infection: acute infection, clinical latency, and AIDS. Acute infection The initial period following the contraction of HIV is called acute HIV, primary HIV or acute retroviral syndrome. Many individuals develop an influenza-like illness or a mononucleosis-like illness 2–4 weeks after exposure while others have no significant symptoms. Symptoms occur in 40–90% of cases and most commonly include fever, large tender lymph nodes, throat inflammation, a rash, headache, tiredness, and/or sores of the mouth and genitals. The rash, which occurs in 20–50% of cases, presents itself on the trunk and is maculopapular, classically. Some people also develop opportunistic infections at this stage. Gastrointestinal symptoms, such as vomiting or diarrhea may occur. Neurological symptoms of peripheral neuropathy or Guillain–Barré syndrome also occurs. The duration of the symptoms varies, but is usually one or two weeks. Owing to their nonspecific character, these symp...

Transmission

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Average per act risk of getting HIV by exposure route to an infected source Exposure route Chance of infection Blood transfusion 90% Childbirth (to child) 25% clarification needed Needle-sharing injection drug use 0.67% Percutaneous needle stick 0.30% Receptive anal intercourse* 0.04–3.0% Insertive anal intercourse* 0.03% Receptive penile-vaginal intercourse* 0.05–0.30% Insertive penile-vaginal intercourse* 0.01–0.38% Receptive oral intercourse*§ 0–0.04% Insertive oral intercourse*§ 0–0.005% * assuming no condom use § source refers to oral intercourse performed on a man HIV is spread by three main routes: sexual contact, significant exposure to infected body fluids or tissues, and from mother to child during pregnancy, delivery, or breastfeeding (known as vertical transmission). There is no risk of acquiring HIV if exposed to feces, nasal secretions, saliva, sputum, sweat, tears, urine, or vomit unless these are contaminated with blood. It is also...

Virology

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HIV is the cause of the spectrum of disease known as HIV/AIDS. HIV is a retrovirus that primarily infects components of the human immune system such as CD4+ T cells, macrophages and dendritic cells. It directly and indirectly destroys CD4+ T cells. HIV is a member of the genus Lentivirus , part of the family Retroviridae . Lentiviruses share many morphological and biological characteristics. Many species of mammals are infected by lentiviruses, which are characteristically responsible for long-duration illnesses with a long incubation period. Lentiviruses are transmitted as single-stranded, positive-sense, enveloped RNA viruses. Upon entry into the target cell, the viral RNA genome is converted (reverse transcribed) into double-stranded DNA by a virally encoded reverse transcriptase that is transported along with the viral genome in the virus particle. The resulting viral DNA is then imported into the cell nucleus and integrated into the cellular DNA by a virally encoded integrase and ...

Pathophysiology

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After the virus enters the body there is a period of rapid viral replication, leading to an abundance of virus in the peripheral blood. During primary infection, the level of HIV may reach several million virus particles per milliliter of blood. This response is accompanied by a marked drop in the number of circulating CD4+ T cells. The acute viremia is almost invariably associated with activation of CD8+ T cells, which kill HIV-infected cells, and subsequently with antibody production, or seroconversion. The CD8+ T cell response is thought to be important in controlling virus levels, which peak and then decline, as the CD4+ T cell counts recover. A good CD8+ T cell response has been linked to slower disease progression and a better prognosis, though it does not eliminate the virus. Ultimately, HIV causes AIDS by depleting CD4+ T cells. This weakens the immune system and allows opportunistic infections. T cells are essential to the immune response and without them, the body cannot figh...

Diagnosis

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Days after exposure needed for the test to be accurate Blood test Days Antibody test (rapid test, ELISA 3rd gen) 23–90 Antibody and p24 antigen test (ELISA 4th gen) 18–45 PCR 10–33 HIV/AIDS is diagnosed via laboratory testing and then staged based on the presence of certain signs or symptoms. HIV screening is recommended by the United States Preventive Services Task Force for all people 15 years to 65 years of age, including all pregnant women. Additionally, testing is recommended for those at high risk, which includes anyone diagnosed with a sexually transmitted illness. In many areas of the world, a third of HIV carriers only discover they are infected at an advanced stage of the disease when AIDS or severe immunodeficiency has become apparent. HIV testing Most people infected with HIV develop specific antibodies (i.e. seroconvert) within three to twelve weeks after the initial infection. Diagnosis of primary HIV before seroconversion is done by measuring HIV-RNA or p2...

Prevention

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Sexual contact Consistent condom use reduces the risk of HIV transmission by approximately 80% over the long term. When condoms are used consistently by a couple in which one person is infected, the rate of HIV infection is less than 1% per year. There is some evidence to suggest that female condoms may provide an equivalent level of protection. Application of a vaginal gel containing tenofovir (a reverse transcriptase inhibitor) immediately before sex seems to reduce infection rates by approximately 40% among African women. By contrast, use of the spermicide nonoxynol-9 may increase the risk of transmission due to its tendency to cause vaginal and rectal irritation. Circumcision in Sub-Saharan Africa "reduces the acquisition of HIV by heterosexual men by between 38% and 66% over 24 months". Owing to these studies, both the World Health Organization and UNAIDS recommended male circumcision in 2007 as a method of preventing female-to-male HIV transmission in areas with high ra...

Treatment

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There is currently no cure, nor an effective HIV vaccine. Treatment consists of highly active antiretroviral therapy (HAART) which slows progression of the disease. As of 2010update more than 6.6 million people were receiving this in low- and middle-income countries. Treatment also includes preventive and active treatment of opportunistic infections. As of March 2020update, two persons have been successfully cleared of HIV. Rapid initiation of anti-retroviral therapy within one week of diagnosis appear to improve treatment outcomes in low and medium-income settings. Antiviral therapy Current HAART options are combinations (or "cocktails") consisting of at least three medications belonging to at least two types, or "classes", of antiretroviral agents. Initially, treatment is typically a non-nucleoside reverse transcriptase inhibitor (NNRTI) plus two nucleoside analog reverse transcriptase inhibitors (NRTIs). Typical NRTIs include: zidovudine (AZT) or tenofovir (TDF) ...

Prognosis

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HIV/AIDS has become a chronic rather than an acutely fatal disease in many areas of the world. Prognosis varies between people, and both the CD4 count and viral load are useful for predicted outcomes. Without treatment, average survival time after infection with HIV is estimated to be 9 to 11 years, depending on the HIV subtype. After the diagnosis of AIDS, if treatment is not available, survival ranges between 6 and 19 months. HAART and appropriate prevention of opportunistic infections reduces the death rate by 80%, and raises the life expectancy for a newly diagnosed young adult to 20–50 years. This is between two thirds and nearly that of the general population. If treatment is started late in the infection, prognosis is not as good: for example, if treatment is begun following the diagnosis of AIDS, life expectancy is ~10–40 years. Half of infants born with HIV die before two years of age without treatment. The primary causes of death from HIV/AIDS are opportunistic infections and...

Epidemiology

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HIV/AIDS is a global pandemic. As of 2016update approximately 36.7 million people worldwide have HIV, the number of new infections that year being about 1.8 million. This is down from 3.1 million new infections in 2001. Slightly over half the infected population are women and 2.1 million are children. It resulted in about 1 million deaths in 2016, down from a peak of 1.9 million in 2005. Sub-Saharan Africa is the region most affected. In 2010, an estimated 68% (22.9 million) of all HIV cases and 66% of all deaths (1.2 million) occurred in this region. This means that about 5% of the adult population is infected and it is believed to be the cause of 10% of all deaths in children. Here, in contrast to other regions, women comprise nearly 60% of cases. South Africa has the largest population of people with HIV of any country in the world at 5.9 million. Life expectancy has fallen in the worst-affected countries due to HIV/AIDS; for example, in 2006 it was estimated that it had dropped fro...

History

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Discovery The first news story on the disease appeared May 18, 1981 in the gay newspaper New York Native . AIDS was first clinically reported on June 5, 1981, with five cases in the United States. The initial cases were a cluster of injecting drug users and gay men with no known cause of impaired immunity who showed symptoms of Pneumocystis carinii pneumonia (PCP), a rare opportunistic infection that was known to occur in people with very compromised immune systems. Soon thereafter, an unexpected number of homosexual men developed a previously rare skin cancer called Kaposi's sarcoma (KS). Many more cases of PCP and KS emerged, alerting U.S. Centers for Disease Control and Prevention (CDC) and a CDC task force was formed to monitor the outbreak. In the early days, the CDC did not have an official name for the disease, often referring to it by way of diseases associated with it, such as lymphadenopathy, the disease after which the discoverers of HIV originally named the virus. They...

Society and culture

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Stigma AIDS stigma exists around the world in a variety of ways, including ostracism, rejection, discrimination and avoidance of HIV-infected people; compulsory HIV testing without prior consent or protection of confidentiality; violence against HIV-infected individuals or people who are perceived to be infected with HIV; and the quarantine of HIV-infected individuals. Stigma-related violence or the fear of violence prevents many people from seeking HIV testing, returning for their results, or securing treatment, possibly turning what could be a manageable chronic illness into a death sentence and perpetuating the spread of HIV. AIDS stigma has been further divided into the following three categories: Instrumental AIDS stigma —a reflection of the fear and apprehension that are likely to be associated with any deadly and transmissible illness. Symbolic AIDS stigma —the use of HIV/AIDS to express attitudes toward the social groups or lifestyles perceived to be associated with the diseas...

Research

HIV/AIDS research includes all medical research which attempts to prevent, treat, or cure HIV/AIDS, along with fundamental research about the nature of HIV as an infectious agent, and about AIDS as the disease caused by HIV. Many governments and research institutions participate in HIV/AIDS research. This research includes behavioral health interventions such as sex education, and drug development, such as research into microbicides for sexually transmitted diseases, HIV vaccines, and antiretroviral drugs. Other medical research areas include the topics of pre-exposure prophylaxis, post-exposure prophylaxis, and circumcision and HIV. Public health officials, researchers, and programs can gain a more comprehensive picture of the barriers they face, and the efficacy of current approaches to HIV treatment and prevention, by tracking standard HIV indicators. Use of common indicators is an increasing focus of development organizations and researchers.