See stuff ooo....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. As the infection progresses, it interferes more with the immune system, increasing the risk of common infections like tuberculosis, as well as other opportunistic infections, and tumors that rarely affect people who have working immune systems. These late symptoms of infection are referred to as AIDS. This stage is often also associated with 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 breastfeeding. Some bodily fluids, such as saliva and tears, do not transmit HIV. Methods of prevention include safe sex, needle-exchange programs, treating those who are infected, and male circumcision. Disease in a baby can often be prevented by giving both the mother and child antiretroviral medication. There is no cure or vaccine; however, antiretroviral treatment can slow the course of the disease and may lead to a near-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 about 36.9 million people were living with HIV and it resulted in 1.2 million deaths.[8] Most of those infected live in sub-Saharan Africa. Between its discovery and 2014 AIDS has caused an estimated 39 million deaths worldwide.[15] HIV/AIDS is considered a pandemic—a disease outbreak which is present over a large area and is actively spreading. HIV is believed to have originated in west-central Africa during the late 19th or early 20th century. AIDS was first recognized by the United States Centers for Disease Control and Prevention (CDC) in 1981 and its cause—HIV infection—was identified in the early part of the decade.
HIV/AIDS has had a great impact on society, both as an illness and as a source of discrimination. The disease also has large economic impacts. There are many misconceptions about HIV/AIDS such as the belief that it can be transmitted by casual non-sexual contact. The disease has become subject to many controversies involving religion including the Catholic church's decision not to support condom use as prevention. It has attracted international medical and political attention as well as large-scale funding since it was identified in the 1980s.
Acute infection
Main symptoms of acute HIV infection
Due to their nonspecific character, these symptoms are not often recognized as signs of HIV infection. Even cases that do get seen by a family doctor or a hospital are often misdiagnosed as one of the many common infectious diseases with overlapping symptoms. Thus, it is recommended that HIV be considered in people presenting an unexplained fever who may have risk factors for the infection.[25]
Clinical latency
The initial symptoms are followed by a stage called clinical latency, asymptomatic HIV, or chronic HIV.[2] Without treatment, this second stage of the natural history of HIV infection can last from about three years[27] to over 20 years[28] (on average, about eight years).[29] While typically there are few or no symptoms at first, near the end of this stage many people experience fever, weight loss, gastrointestinal problems and muscle pains.[2] Between 50 and 70% of people also develop persistent generalized lymphadenopathy, characterized by unexplained, non-painful enlargement of more than one group of lymph nodes (other than in the groin) for over three to six months.[3]Although most HIV-1 infected individuals have a detectable viral load and in the absence of treatment will eventually progress to AIDS, a small proportion (about 5%) retain high levels of CD4+ T cells (T helper cells) without antiretroviral therapy for more than 5 years.[25][30] These individuals are classified as HIV controllers or long-term nonprogressors (LTNP).[30] Another group consists of those who maintain a low or undetectable viral load without anti-retroviral treatment, known as "elite controllers" or "elite suppressors". They represent approximately 1 in 300 infected persons.[31]
Acquired immunodeficiency syndrome
Main symptoms of AIDS.
Opportunistic infections may be caused by bacteria, viruses, fungi, and parasites that are normally controlled by the immune system.[32] Which infections occur depends partly on what organisms are common in the person's environment.[25] These infections may affect nearly every organ system.[33]
People with AIDS have an increased risk of developing various viral-induced cancers, including Kaposi's sarcoma, Burkitt's lymphoma, primary central nervous system lymphoma, and cervical cancer.[26] Kaposi's sarcoma is the most common cancer occurring in 10 to 20% of people with HIV.[34] The second most common cancer is lymphoma, which is the cause of death of nearly 16% of people with AIDS and is the initial sign of AIDS in 3 to 4%.[34] Both these cancers are associated with human herpesvirus 8.[34] Cervical cancer occurs more frequently in those with AIDS because of its association with human papillomavirus (HPV).[34] Conjunctival cancer (of the layer that lines the inner part of eyelids and the white part of the eye) is also more common in those with HIV.[35]
Additionally, people with AIDS frequently have systemic symptoms such as prolonged fevers, sweats (particularly at night), swollen lymph nodes, chills, weakness, and unintended weight loss.[36] Diarrhea is another common symptom, present in about 90% of people with AIDS.[37] They can also be affected by diverse psychiatric and neurological symptoms independent of opportunistic infections and cancers.[38]
Transmission
Risk of transmission increases in the presence of many sexually transmitted infections[55] and genital ulcers.[49] Genital ulcers appear to increase the risk approximately fivefold.[49] Other sexually transmitted infections, such as gonorrhea, chlamydia, trichomoniasis, and bacterial vaginosis, are associated with somewhat smaller increases in risk of transmission.[54]
The viral load of an infected person is an important risk factor in both sexual and mother-to-child transmission.[56] During the first 2.5 months of an HIV infection a person's infectiousness is twelve times higher due to this high viral load.[54] If the person is in the late stages of infection, rates of transmission are approximately eightfold greater.[49]
Commercial sex workers (including those in pornography) have an increased rate of HIV.[57][58] Rough sex can be a factor associated with an increased risk of transmission.[59] Sexual assault is also believed to carry an increased risk of HIV transmission as condoms are rarely worn, physical trauma to the vagina or rectum is likely, and there may be a greater risk of concurrent sexually transmitted infections.[60]
Body fluids
HIV is transmitted in about 93% of blood transfusions using infected blood.[61] In developed countries the risk of acquiring HIV from a blood transfusion is extremely low (less than one in half a million) where improved donor selection and HIV screening is performed;[10] for example, in the UK the risk is reported at one in five million[63] and in the United States it was one in 1.5 million in 2008.[64] In low income countries, only half of transfusions may be appropriately screened (as of 2008),[65] 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% of global infections.[10][66] Although rare because of screening, it is possible to acquire HIV from organ and tissue transplantation.[67]
Unsafe medical injections play a significant role in HIV spread in sub-Saharan Africa. In 2007, between 12 and 17% of infections in this region were attributed to medical syringe use.[68] The World Health Organization estimates the risk of transmission as a result of a medical injection in Africa at 1.2%.[68] Significant risks are also associated with invasive procedures, assisted delivery, and dental care in this area of the world.[68]
People giving or receiving tattoos, piercings, and scarification are theoretically at risk of infection but no confirmed cases have been documented.[69] It is not possible for mosquitoes or other insects to transmit HIV.[70]
Mother-to-child
Main articles: HIV and pregnancy and HIV and breastfeeding
HIV can be transmitted from mother to child during pregnancy, during
delivery, or through breast milk resulting in infection in the baby.[71][72] This is the third most common way in which HIV is transmitted globally.[10] In the absence of treatment, the risk of transmission before or during birth is around 20% and in those who also breastfeed 35%.[71] As of 2008, vertical transmission accounted for about 90% of cases of HIV in children.[71] With appropriate treatment the risk of mother-to-child infection can be reduced to about 1%.[71] Preventive treatment involves the mother taking antiretrovirals during pregnancy and delivery, an elective caesarean section, avoiding breastfeeding, and administering antiretroviral drugs to the newborn.[73] Antiretrovirals when taken by either the mother or the infant decrease the risk of transmission in those who do breastfeed.[74] Many of these measures are however not available in the developing world.[73] If blood contaminates food during pre-chewing it may pose a risk of transmission.[69]
Virology
Diagram of a HIV virion structure
Prevention
Main article: Prevention of HIV/AIDS
AIDS Clinic, McLeod Ganj, Himachal Pradesh, India, 2010
Sexual contact
Consistent condom use reduces the risk of HIV transmission by approximately 80% over the long term.[103] 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.[104] There is some evidence to suggest that female condoms may provide an equivalent level of protection.[105] 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.[106] By contrast, use of the spermicide nonoxynol-9 may increase the risk of transmission due to its tendency to cause vaginal and rectal irritation.[107]Circumcision in Sub-Saharan Africa "reduces the acquisition of HIV by heterosexual men by between 38% and 66% over 24 months".[108] Based on these studies, the World Health Organization and UNAIDS both recommended male circumcision as a method of preventing female-to-male HIV transmission in 2007.[109] Whether it protects against male-to-female transmission is disputed[110][111] and whether it is of benefit in developed countries and among men who have sex with men is undetermined.[112][113][114] The International Antiviral Society, however, does recommend for all sexually active heterosexual males and that it be discussed as an option with men who have sex with men.[115] Some experts fear that a lower perception of vulnerability among circumcised men may cause more sexual risk-taking behavior, thus negating its preventive effects.[116]
Programs encouraging sexual abstinence do not appear to affect subsequent HIV risk.[117] Evidence of any benefit from peer education is equally poor.[118] Comprehensive sexual education provided at school may decrease high risk behavior.[119] A substantial minority of young people continues to engage in high-risk practices despite knowing about HIV/AIDS, underestimating their own risk of becoming infected with HIV.[120] Voluntary counseling and testing people for HIV does not affect risky behavior in those who test negative but does increase condom use in those who test positive.[121] It is not known whether treating other sexually transmitted infections is effective in preventing HIV.[55]
Pre-exposure
Antiretroviral treatment among people with HIV whose CD4 count ≤ 550 cells/µL is a very effective way to prevent HIV infection of their partner (a strategy known as treatment as prevention, or TASP).[122] TASP is associated with a 10 to 20 fold reduction in transmission risk.[122][123] Pre-exposure prophylaxis (PrEP) with a daily dose of the medications tenofovir, with or without emtricitabine, is effective in a number of groups including men who have sex with men, couples where one is HIV positive, and young heterosexuals in Africa.[106] It may also be effective in intravenous drug users with a study finding a decrease in risk of 0.7 to 0.4 per 100 person years.[124]Universal precautions within the health care environment are believed to be effective in decreasing the risk of HIV.[125] Intravenous drug use is an important risk factor and harm reduction strategies such as needle-exchange programmes and opioid substitution therapy appear effective in decreasing this risk.[126][127]
Post-exposure
A course of antiretrovirals administered within 48 to 72 hours after exposure to HIV-positive blood or genital secretions is referred to as post-exposure prophylaxis (PEP).[128] The use of the single agent zidovudine reduces the risk of a HIV infection five-fold following a needle-stick injury.[128] As of 2013, the prevention regimen recommended in the United States consists of three medications—tenofovir, emtricitabine and raltegravir—as this may reduce the risk further.[129]PEP treatment is recommended after a sexual assault when the perpetrator is known to be HIV positive, but is controversial when their HIV status is unknown.[130] The duration of treatment is usually four weeks[131] and is frequently associated with adverse effects—where zidovudine is used, about 70% of cases result in adverse effects such as nausea (24%), fatigue (22%), emotional distress (13%) and headaches (9%).[46]
Mother-to-child
Main article: HIV and pregnancy
Programs to prevent the vertical transmission of HIV (from mothers to children) can reduce rates of transmission by 92–99%.[71][126]
This primarily involves the use of a combination of antiviral
medications during pregnancy and after birth in the infant and
potentially includes bottle feeding rather than breastfeeding.[71][132]
If replacement feeding is acceptable, feasible, affordable,
sustainable, and safe, mothers should avoid breastfeeding their infants;
however exclusive breastfeeding is recommended during the first months
of life if this is not the case.[133]
If exclusive breastfeeding is carried out, the provision of extended
antiretroviral prophylaxis to the infant decreases the risk of
transmission.[134] In 2015, Cuba became the first country in the world to eradicate mother-to-child transmission of HIV.[135]Vaccination
Main article: HIV vaccine
Currently, there is no licensed vaccine for HIV or AIDS.[12] The most effective vaccine trial to date, RV 144,
was published in 2009 and found a partial reduction in the risk of
transmission of roughly 30%, stimulating some hope in the research
community of developing a truly effective vaccine.[136] Further trials of the RV 144 vaccine are ongoing.[137][138]Treatment
There is currently no cure or effective HIV vaccine. Treatment consists of highly active antiretroviral therapy (HAART) which slows progression of the disease.[139] As of 2010 more than 6.6 million people were taking them in low and middle income countries.[140] Treatment also includes preventive and active treatment of opportunistic infections.Antiviral therapy
Stribild - a common once-daily ART regime consisting of elvitegravir, emtricitabine, tenofovir and the booster cobicistat
The World Health Organization and United States recommends antiretrovirals in people of all ages including pregnant women as soon as the diagnosis is made regardless of CD4 count.[13][115][143] Once treatment is begun it is recommended that it is continued without breaks or "holidays".[26] Many people are diagnosed only after treatment ideally should have begun.[26] The desired outcome of treatment is a long term plasma HIV-RNA count below 50 copies/mL.[26] Levels to determine if treatment is effective are initially recommended after four weeks and once levels fall below 50 copies/mL checks every three to six months are typically adequate.[26] Inadequate control is deemed to be greater than 400 copies/mL.[26] Based on these criteria treatment is effective in more than 95% of people during the first year.[26]
Benefits of treatment include a decreased risk of progression to AIDS and a decreased risk of death.[144] In the developing world treatment also improves physical and mental health.[145] With treatment there is a 70% reduced risk of acquiring tuberculosis.[141] Additional benefits include a decreased risk of transmission of the disease to sexual partners and a decrease in mother-to-child transmission.[141] The effectiveness of treatment depends to a large part on compliance.[26] Reasons for non-adherence include poor access to medical care,[146] inadequate social supports, mental illness and drug abuse.[147] The complexity of treatment regimens (due to pill numbers and dosing frequency) and adverse effects may reduce adherence.[148] Even though cost is an important issue with some medications,[149] 47% of those who needed them were taking them in low and middle income countries as of 2010[140] and the rate of adherence is similar in low-income and high-income countries.[150]
Specific adverse events are related to the antiretroviral agent taken.[151] Some relatively common adverse events include: lipodystrophy syndrome, dyslipidemia, and diabetes mellitus, especially with protease inhibitors.[3] Other common symptoms include diarrhea,[151][152] and an increased risk of cardiovascular disease.[153] Newer recommended treatments are associated with fewer adverse effects.[26] Certain medications may be associated with birth defects and therefore may be unsuitable for women hoping to have children.[26]
Treatment recommendations for children are somewhat different from those for adults. The World Health Organisation recommends treating all children less than 5 years of age; children above 5 are treated like adults.[154] The United States guidelines recommend treating all children less than 12 months of age and all those with HIV RNA counts greater than 100,000 copies/mL between one year and five years of age.[155
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