HIV and acquired immunodeficiency syndrome (HIV / AIDS) is a spectrum of diseases caused by infection with
After initial infection, a person may not notice any symptoms or may experience a brief period of influenza illness.Typically, this is followed by a prolonged period without symptoms.As infection progresses, more interferes with the immune system, increasing the risk common infections such as tuberculosis and other opportunistic infections and tumors that rarely affects people who work late systems.These immune symptoms of infection are known as AIDS.This stage often also associated with weight loss .
is spread primarily through unprotected sex (including anal and oral sex), contaminated blood transfusions, hypodermic needles, and from mother to child during pregnancy, childbirth or breastfeeding. Some body fluids, such as saliva and tears, do not transmit HIV. Prevention methods include safe sex, needle exchange programs, treatment of infected persons, and male circumcision. A baby disease can often be prevented by giving both mother and child medication.There antiretroviral no cure or vaccine; However, antiretroviral treatment can slow the course of the disease and can lead to an almost normal life expectancy.Treatment is recommended as soon as the diagnosis is made. Without treatment, the average survival time after infection is 11 years.
In 2014 some 36.9 million people were living with
HIV and the result was 1.2 million deaths. Most of those infected live in sub-Saharan Africa. Between its discovery and 2014
AIDS has caused an estimated 39 million deaths worldwide.
HIV / AIDS is considered a pandemic, an outbreak of a disease that is present in a large area and is spreading actively. HIV is thought to have originated in West Africa Central during the late 19th or early 20th century AIDS was first identified by the Centers for Disease Control and Prevention (CDC) in 1981 and its cause infection HIV-was identified in the early part of the decade.
HIV / AIDS has had a major impact on society, both as a disease and as a source of discrimination. The disease also has great economic impacts.There are many misconceptions about HIV /
AIDS, such as the belief that can be transmitted by casual non-sexual contact. The disease has become the subject of many controversies involving religion including the decision of the Catholic Church does not support the use of condoms as prevention.It has attracted medical attention and international politics, as well as large-scale financing since it was identified in the 1980s
The second most frequent mode of transmission of
HIV through blood and blood products. transmission via blood can be through sharing needles during intravenous drug use, pricked with a needle, transfusion of contaminated blood or blood products or medical injections with unsterilized equipment. The risk of sharing a needle during injection drug use is between 0.63 and 2.4% for each event, with an average of 0.8% .The risk of contracting HIV from a needle stick from a HIV-infected person is estimated at 0.3% (about 1 in 333) for each act and risk after exposure of mucous membranes to infected blood as 0.09% (about 1 in 1000) per act. In the United States injecting drug users make up 12% of all new HIV cases in 2009, and in some areas more than 80% of people who inject drugs are HIV positive.
HIV is transmitted in approximately 93% of blood transfusions using infected blood. In developed countries, the risk of contracting
HIV from a blood transfusion is extremely low (less than one half million), which takes place a better selection of donors and HIV screening; For example, in the UK the risk is reported at one and five million in the United States was one of 1.5 million in 2008 in low-income countries, only half the transfusions you can properly screened (from 2008), and it is estimated that up to 15% of HIV infections in these areas come from transfusion of infected blood and blood products, representing between 5% and 10% Although the global infections is rare due to the detection, it is possible to get
HIV from organ and tissue transplantation.
unsafe medical injections play an important role in the spread of HIV in sub-Saharan Africa. In 2007, between 12 and 17% of infections in this region is attributed to the use of medical syringe. The World Health Organization estimates that the risk of transmission as a result of a medical injection in Africa at 1.2% .Significant risks are also associated with invasive procedures, assisted delivery, and dental care in this area of the world.
People give or receive tattoos, piercings, and scarification are theoretically the risk of infection, but there are no confirmed cases they have been documented. It is not possible for mosquitoes or other insects transmit HIV.
HIV is the cause of the spectrum of the 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 Retroviridae.Lentiviruses family share many morphological and biological characteristics. Many species of mammals are infected by lentiviruses, which are characteristically responsible for long-term illnesses with a long incubation period. Lentiviruses are transmitted as positive-sense single-stranded, enveloped RNA viruses. Upon entry into the target cell, the viral RNA genome is converted (reverse transcription) in double-stranded DNA by a virally encoded reverse transcriptase that is transported along with the viral genome into the virus particle. The resulting viral DNA is then imported into the cell nucleus and integrates into cellular DNA encoded by a virus integrase and host cofactors. Once integrated, the virus may become latent, allowing the virus and its host cell to avoid detection by the immune system. Alternatively, the virus can be transcribed, the production of new RNA genomes and viral proteins that are packaged and released from the cell as new virus particles that begin the replication cycle again.
HIV now cases of transmission between T CD4 + cells by two parallel paths are known: the free propagation cells and spread from cell to cell, that is, hybrid mechanisms diffusion is used In diffusion cell free particles virus outbreak of infection. T cells enter the blood / extracellular fluid and then infect other T cell after a chance encounter. [81] HIV may also spread by direct transmission from one cell to another by a process of spreading from cell to cell. [82] [83] hybrid mechanisms spread of HIV contributes to the continuous replication of virus with antiretroviral therapies.
They have characterized two types of HIV: HIV-1 and HIV-2. HIV-1 is the virus that was originally discovered (and initially also referred to as LAV or HTLV-III). It is more virulent, more infectious, [85] and is the cause of most HIV infections in the world. The lower infectivity of HIV-2 compared to HIV-1 implies that fewer of those exposed to HIV-2 were infected by exposure. Because of its relatively low capacity transmission, HIV-2 is largely confined to West Africa.
pathophysiology
Main article: Pathophysiology of HIV / AIDS
File: HIV and AIDS explained in a simple way.webm
HIV / AIDS explained in a simple manner
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 decrease in the number of circulating CD4 + T cells. Viremia acute almost invariably associated with is the activation of CD8 + T cells that kill cells infected by HIV, and subsequently with antibody production, or seroconversion. The response of CD8 + T cells is thought to be important in controlling virus levels, which peak and then decreases as the CD4 + T cells recover. A good response of CD8 + T cells has been linked to progression of disease slower and prognosis, although 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 for immune response and without them, the body can not fight infections or kill cancer cells. The mechanism of cell depletion CD4 + T difference in the acute and chronic phases. During the acute phase, HIV induced cell-lysis and death of cells infected by cytotoxic T cells accounts for the depletion of CD4 + T cells, despite apoptosis may also be a factor. During the chronic phase, the consequences of generalized immune activation coupled with the gradual loss of the ability of the immune system to generate new T cells appear to account for the slow decline in the number of CD4 + T cells.
Although symptoms characteristic immunodeficiency AIDS do not appear for years after a person is infected, most of the loss of CD4 + T cells occurs during the first few weeks of infection, especially in the intestinal mucosa, which houses most lymphocytes are found in the body. The reason for the preferential loss of T cells of mucosal CD4 + is most T cells of mucosal CD4 + expressing CCR5 protein that HIV uses as a co-receptor for accessing cells while only a small fraction of CD4 + T cells in the bloodstream do so. A specific genetic change that alters the CCR5 protein when present on both chromosomes very effectively prevents HIV-1
HIV seeks out and destroys CCR5 cells expressing CD4 + T during acute infection. A vigorous immune response eventually controls infection and clinically latent phase starts. CD4 + T cells in mucosal tissues remain HIV replication affected.Continuous particularly causes a state of persistent along phase.Immune chronic immune activation generalized activation, reflected in the increased activation status of immune cells and the release of pro-inflammatory cytokines, the results of the activity of several HIV gene products and the immune response to HIV continuous replication. It is also linked to the breakdown of immune surveillance system gastrointestinal mucosal barrier caused by the depletion of CD4 + T cells lining during the acute phase of the disease.
