Drug respiratory tract infection that often recurs

acquired immune deficiency syndrome or acquiredimmunodeficiency syndrome (aids) is a disease of the human immune system caused by the humanimmunodeficiency virus (hiv). the illness interferes with the immune system making peoplewith aids much more likely to get infections, including opportunistic infections and tumorsthat do not affect people with working immune systems. this susceptibility gets worse asthe disease continues. hiv is transmitted in many ways, such as anal,vaginal or oral sex, blood transfusion, contaminated hypodermic needles, exchange between motherand baby during pregnancy, childbirth, and breastfeeding. it can be transmitted by anycontact of a mucous membrane or the bloodstream with a bodily fluid that has the virus init, such as the blood, semen,vaginal fluid,

preseminal fluid, or breast milk from an infectedperson. the virus and disease are often referred totogether as hiv/aids. the disease is a major health problem in many parts of the world,and is considered a pandemic, a disease outbreak that is not only present over a large areabut is actively spreading. in 2009, the world health organization (who) estimated that thereare 33.4 million people worldwide living with hiv/aids, with 2.7 million new hiv infectionsper year and 2.0 million annual deaths due to aids. in 2007,unaids estimated: 33.2 millionpeople worldwide had aids that year; aids killed 2.1 million people in the course ofthat year, including 330,000 children, and 76% of those deaths occurred in sub-saharanafrica. according to unaids 2009 report, worldwide

some 60 million people have been infectedsince the start of the pandemic, with some 25 million deaths, and 14 million orphanedchildren in southern africa alone. genetic research indicates that hiv originatedin west-central africa during the late nineteenth or early twentieth century. aids was firstrecognized by the u. s. centers for disease control and prevention in 1981 and its cause,hiv, identified in the early 1980s. although treatments for hiv/aids can slowthe course of the disease, there is no known cure or vaccine. antiretroviraltreatment reducesboth the deaths and new infections from hiv/aids, but these drugs are expensive and the medicationsarenot available in all countries. due to the difficulty in treating hiv infection, preventinginfection is a key aim in controlling the

aids pandemic, with health organizations promotingsafe sex and needle-exchange programmes in attempts to slow the spread of the virus.contents • 1 signs and symptomso 1.1 pulmonary o 1.2 gastrointestinalo 1.3 neurological and psychiatric o 1.4 tumorso 1.5 other infections • 2 causeo 2.1 sexual transmission o 2.2 blood productso 2.3 perinatal transmission • 3 pathophysiologyo 3.1 cells affected • 4 diagnosiso 4.1 who disease staging system

o 4.2 cdc classification systemo 4.3 hiv test • 5 preventiono 5.1 sexual contact o 5.2 body fluid exposureo 5.3 mother-to-child o 5.4 education• 6 management o 6.1 antiviral therapyo 6.2 complementary and alternative medicine • 7 prognosis• 8 epidemiology • 9 history and origin• 10 society and culture o 10.1 stigmao 10.2 economic impact o 10.3 religion and aidso 10.4 aids denialism

o 10.5 kgb disinformationo 10.6 government reaction • 11 research directions• 12 see also • 13 notes and references• 14 further reading • 15 external linkssigns and symptoms main symptoms of aids. x-ray of pneumocystis pneumonia (pcp). thereis increased white (opacity) in the lower lungs on both sides, characteristic of pcpthe symptoms of aids are primarily the result of conditions that do not normally developin individuals with healthy immune systems. most of these conditions are infections causedby bacteria, viruses, fungi and parasites

that are normally controlled by the elementsof the immune system that hiv damages. opportunistic infections are common in peoplewith aids. these infections affect nearly every organ system.people with aids also have an increased risk of developing various cancers such as kaposi'ssarcoma, cervical cancer and cancers of the immune system known as lymphomas. additionally,people with aids often have systemic symptoms of infection like fevers, sweats (particularlyat night), swollen glands, chills, weakness, and weight loss. the specific opportunisticinfections that aids patients develop depend in part on the prevalence of these infectionsin the geographic area in which the patient lives.pulmonary

pneumocystis pneumonia (originally known aspneumocystis carinii pneumonia, and still abbreviated as pcp, which now stands for pneumocystispneumonia) is relatively rare in healthy, immunocompetent people, but common among hiv-infectedindividuals. it is caused by pneumocystis jirovecii.before the advent of effective diagnosis, treatment and routine prophylaxis in westerncountries, it was a common immediate cause of death. in developing countries, it is stillone of the first indications of aids in untested individuals, although it does not generallyoccur unless the cd4 count is less than 200 cells per âµl of blood.tuberculosis (tb) is unique among infections associated with hiv because it is transmissibleto immunocompetent people via the respiratory

route, and is not easily treatable once identified.multidrug resistance is a serious problem. tuberculosiswith hiv co-infection (tb/hiv)is a major world health problem according to the world health organization: in 2007,456,000 deaths among incident tb cases were hiv-positive, a third of all tb deaths andnearly a quarter of the estimated 2 million hiv deaths in that year. even though its incidencehas declined because of the use of directly observed therapy and other improved practicesin western countries, this is not the case in developing countries where hiv is mostprevalent. in early-stage hiv infection (cd4 count >300 cells per âµl), tb typically presentsas a pulmonary disease. in advanced hiv infection, tb often presents atypically with extrapulmonary(systemic) disease a common feature. symptoms

are usually constitutional and are not localizedto one particular site, often affecting bone marrow, bone, urinary and gastrointestinaltracts, liver, regional lymph nodes, and the central nervous system.gastrointestinal esophagitis is an inflammation of the liningof the lower end of the esophagus (gullet or swallowing tube leading to thestomach).in hiv-infected individuals, this is normally due to fungal (candidiasis) or viral (herpessimplex-1 orcytomegalovirus) infections. in rare cases, it could be due to mycobacteria.unexplained chronic diarrhea in hiv infection is due to many possible causes, includingcommon bacterial (salmonella, shigella, listeria or campylobacter) and parasitic infections;and uncommon opportunistic infections such

as cryptosporidiosis, microsporidiosis, mycobacteriumavium complex (mac) and viruses,astrovirus, adenovirus, rotavirus and cytomegalovirus,(the latter as a course of colitis). in some cases, diarrhea may be a side effectof several drugs used to treat hiv, or it may simply accompany hiv infection, particularlyduring primary hiv infection. it may also be a side effect of antibiotics used to treatbacterial causes of diarrhea (common for clostridium difficile). in the later stages of hiv infection,diarrhea is thought to be a reflection of changes in the way the intestinal tract absorbsnutrients, and may be an important component of hiv-related wasting.neurological and psychiatric hiv infection may lead to a variety of neuropsychiatricsequelae, either by infection of the now susceptible

nervous system by organisms, or as a directconsequence of the illness itself. toxoplasmosis is a disease caused by the single-celledparasite called toxoplasma gondii; it usually infects the brain, causing toxoplasma encephalitis,but it can also infect and cause disease in the eyes and lungs. cryptococcal meningitisis an infection of the meninx (the membrane covering the brain and spinal cord) by thefungus cryptococcus neoformans. it can cause fevers, headache, fatigue, nausea, and vomiting.patients may also develop seizures and confusion; left untreated, it can be lethal.progressive multifocal leukoencephalopathy (pml) is a demyelinating disease, in whichthe gradual destruction of the myelin sheath covering the axons of nerve cells impairsthe transmission of nerve impulses. it is

caused by a virus called jc virus which occursin 70% of the population in latent form, causing disease only when the immune system has beenseverely weakened, as is the case for aids patients. it progresses rapidly, usually causingdeath within months of diagnosis. aids dementia complex (adc) is a metabolicencephalopathy induced by hiv infection and fueled by immune activation of hiv infectedbrain macrophages andmicroglia. these cells are productively infected by hiv and secreteneurotoxins of both host and viral origin. specific neurological impairments are manifestedby cognitive, behavioral, and motor abnormalities that occur after years of hiv infection andare associated with low cd4+ t cell levels and high plasma viral loads.prevalence is 10--20% in western countries

but only 1--2% of hiv infections in india.this difference is possibly due to the hiv subtype in india. aids related mania is sometimesseen in patients with advanced hiv illness; it presents with more irritability and cognitiveimpairment and less euphoria than a manic episodeassociated with true bipolar disorder.unlike the latter condition, it may have a more chronic course. this syndrome is lessoften seen with the advent of multi-drug therapy. tumors kaposi's sarcomapatients with hiv infection have substantially increased incidence of several cancers. thisis primarily due to co-infection with an oncogenic dna virus, especially epstein-barr virus (ebv),kaposi's sarcoma-associated herpesvirus (kshv)

(also known as human herpesvirus-8 ), andhuman papillomavirus (hpv). kaposi's sarcoma (ks) is the most common tumorin hiv-infected patients. the appearance of this tumor in young homosexual men in 1981was one of the first signals of the aids epidemic. caused by a gammaherpes virus called kaposi'ssarcoma-associated herpes virus (kshv), it often appears as purplish nodules on the skin,but can affect other organs, especially the mouth, gastrointestinal tract, and lungs.high-grade b cell lymphomas such as burkitt's lymphoma, burkitt's-like lymphoma, diffuselarge b-cell lymphoma (dlbcl), and primary central nervous system lymphoma present moreoften in hiv-infected patients. these particular cancers often foreshadow a poor prognosis.epstein-barr virus (ebv) or kshv cause many

of these lymphomas. in hiv-infected patients,lymphoma often arises in extranodal sites such as the gastrointestinal tract. when theyoccur in an hiv-infected patient, ks and aggressive b cell lymphomas confer a diagnosis of aids.invasive cervical cancer in hiv-infected women is also considered aids-defining, it is causedby human papillomavirus (hpv). in addition to the aids-defining tumors listedabove, hiv-infected patients are at increased risk of certain other tumors, notably hodgkin'sdisease, anal and rectal carcinomas, hepatocellular carcinomas, head and neck cancers, and lungcancer. some of these are causes by viruses, such as hodgkin's disease (ebv), anal/rectalcancers (hpv), head and neck cancers (hpv), and hepatocellular carcinoma (hepatitis bor c). other contributing factors include

exposure to carcinogens (cigarette smoke forlung cancer), or living for years with subtle immune defects.interestingly, the incidence of many common tumors, such as breast cancer or colon cancer,does not increase in hiv-infected patients. in areas where haart is extensively used totreat aids, the incidence of many aids-related malignancies has decreased, but at the sametime malignant cancers overall have become the most common cause of death of hiv-infectedpatients. in recent years, an increasing proportion of these deaths have been from non-aids-definingcancers. other infectionsaids patients often develop opportunistic infections that present with non-specificsymptoms, especially low-grade fevers and

weight loss. these include opportunistic infectionwith mycobacterium avium-intracellulare and cytomegalovirus (cmv). cmv can cause colitis,as described above, and cmv retinitis can causeblindness.penicilliosis due to penicillium marneffei is now the third most common opportunisticinfection (after extrapulmonary tuberculosis and cryptococcosis) in hiv-positive individualswithin the endemic area of southeast asia. an infection that often goes unrecognizedin aids patients is parvovirus b19. its main consequence is anemia, which is difficultto distinguish from the effects of antiretroviral drugs used to treat aids itself.cause for more details on this topic, see hiv.

scanning electron micrograph of hiv-1, coloredgreen, budding from a cultured lymphocyte. a generalized graph of the relationship betweenhiv 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/mmâ³) hiv rna copies per ml of plasma aids is the ultimate clinical consequenceof infection with hiv. hiv is a retrovirus that primarily infects vital organs of thehuman immune system such as cd4+ t cells (a subset of t cells), macrophages and dendriticcells. it directly and indirectly destroys cd4+ t cells.once the number of cd4+ t cells per microliter (âµl) of blood drops below 200, cellular immunityis lost. acute hiv infection usually progresses

over time to clinical latent hiv infectionand then to early symptomatic hiv infection and later to aids, which is identified eitheron the basis of the amount of cd4+ t cells remaining in the blood, and/or the presenceof 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 mediansurvival time after developing aids is only 9.2 months. however, the rate of clinicaldisease 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'sability to defend against hiv such as the infected person's general immune function.older people have weaker immune systems, and

therefore have a greater risk of rapid diseaseprogression than younger people. poor access to health care and the existenceof coexisting infections such as tuberculosis also may predispose people to faster diseaseprogression. the infected person's genetic inheritance plays an important role and somepeople areresistant to certain strains of hiv. an example of this is people with thehomozygous ccr5-î”32 variation are resistant to infection with certain strains of hiv.hiv is genetically variable and exists as different strains, which cause different ratesof clinical disease progression. there are a number hiv and aids misconceptions.three of the most common are that aids can spread through casual contact, that sexualintercourse with a virgin will cure aids,

and that hiv can infect only homosexual menand drug users. other misconceptions are that any act of anal intercourse between gay mencan lead to aids infection, and that open discussion of homosexuality and hiv in schoolswill lead to increased rates of homosexuality and aids.sexual transmission main article: sexually transmitted diseasesexual transmission occurs with the contact between sexual secretions of one person withthe rectal, genital or oral mucous membranes of another. unprotected sexual acts are riskierfor the receptive partner than for the insertive partner, and the risk for transmitting hivthrough unprotected anal intercourse is greater than the risk from vaginal intercourse ororal sex.

however, oral sex is not entirely safe, ashiv can be transmitted through both insertive and receptive oral sex. sexual assault greatlyincreases the risk of hiv transmission as condoms are rarely employed and physical traumato the vagina or rectum occurs frequently, facilitating the transmission of hiv.drug use has been studied as a possible predictor of hiv transmission. perry n. halkitis foundthat methamphetamine usage does significantly relate to unprotected sexual behavior. thestudy found methamphetamine users to be at a higher risk for contracting hiv.other sexually transmitted infections (sti) increase the risk of hiv transmission andinfection, because they cause the disruption of the normal epithelial barrier bygenitalulceration and/or microulceration; and by

accumulation of pools of hiv-susceptible orhiv-infected cells (lymphocytes and macrophages) in semen and vaginal secretions. epidemiologicalstudies from sub-saharan africa, europe and north america suggest that genital ulcers,such as those caused by syphilis and/orchancroid, increase the risk of becoming infected withhiv by about fourfold. there is also a significant although lesser increase in risk from stissuch as gonorrhea,chlamydia and trichomoniasis, which all cause local accumulations of lymphocytesand macrophages. transmission of hiv depends on the infectiousnessof the index case and the susceptibility of the uninfected partner. infectivity seemsto vary during the course of illness and is not constant between individuals. an undetectableplasma viral load does not necessarily indicate

a low viral load in the seminal liquid orgenital secretions. however, each 10-fold increase in the levelof hiv in the blood is associated with an 81% increased rate of hiv transmission. womenare more susceptible to hiv-1 infection due to hormonal changes, vaginal microbial ecologyand physiology, and a higher prevalence of sexually transmitted diseases.people who have been infected with one strain of hiv can still be infected later on in theirlives by other, more virulent strains. infection is unlikely in a single encounter.high rates of infection have been linked to a pattern of overlapping long-term sexualrelationships. this allows the virus to quickly spread to multiple partners who in turn infecttheir partners. a pattern of serial monogamy

or occasional casual encounters is associatedwith lower rates of infection. hiv spreads readily through heterosexual sexin africa, but less so elsewhere. one possibility being researched is that schistosomiasis,which affects up to 50% of women in parts of africa, damages the lining of the vagina.blood products cdc poster from 1989 highlighting the threatof aids associated with drug use this transmission route is particularly relevantto intravenous drug users, hemophiliacs and recipients of blood transfusionsand bloodproducts. sharing and reusing syringes contaminated with hiv-infected blood represents a majorrisk for infection with hiv. needle sharing is the cause of one third ofall new hiv-infections in north america, china,

and eastern europe. the risk of being infectedwith hiv from a single prick with a needle that has been used on an hiv-infected personis thought to be about 1 in 150 (see table above). post-exposure prophylaxis with anti-hivdrugs can further reduce this risk. this route can also affect people who giveand receive tattoos and piercings. universal precautions are frequently not followed inboth sub-saharan africa and much of asia because of both a shortage of supplies and inadequatetraining. the who estimates that approximately 2.5%of all hiv infections in sub-saharan africa are transmitted through unsafe healthcareinjections. because of this, the united nations general assembly has urged the nations ofthe world to implement precautions to prevent

hiv transmission by health workers.the risk of transmitting hiv to blood transfusion recipients is extremely low in developed countrieswhere improved donor selection and hiv screening is performed. however, according to the who,the overwhelming majority of the world's population does not have access to safe blood and between5% and 10% of the world's hiv infections come from transfusion of infected blood and bloodproducts. perinatal transmissionthe transmission of the virus from the mother to the child can occur in utero during thelast weeks of pregnancy and at childbirth. in the absence of treatment, the transmissionrate between a mother and her child during pregnancy, labor and delivery is 25%.however, when the mother takes antiretroviral

therapy and gives birth by caesarean section,the rate of transmission is just 1%. the risk of infection is influenced by the viral loadof the mother at birth, with the higher the viral load, the higher the risk. breastfeedingalso increases the risk of transmission by about 4 %.pathophysiology this section may require cleanup to meet wikipedia'squality standards. no cleanup reason has been specified. please help improve this sectionif you can. (april 2008) the pathophysiology of aids is complex, asis the case with all syndromes. ultimately, hiv causes aids by depleting cd4+ t helperlymphocytes. this weakens the immune system and allows opportunistic infections. t lymphocytesare essential to the immune response and without

them, the body cannot fight infections orkill cancerous cells. the mechanism of cd4+ t cell depletion differs in the acute andchronic phases. during the acute phase, hiv-induced cell lysisand killing of infected cells by cytotoxic t cells accounts for cd4+ t cell depletion,although apoptosis may also be a factor. during the chronic phase, the consequences of generalizedimmune activation coupled with the gradual loss of the ability of the immune system togenerate new t cells appear to account for the slow decline in cd4+ t cell numbers.although the symptoms of immune deficiency characteristic of aids do not appear for yearsafter a person is infected, the bulk of cd4+ t cell loss occurs during the first weeksof infection, especially in the intestinal

mucosa, which harbors the majority of thelymphocytes found in the body. the reason for the preferential loss of mucosal cd4+t cells is that a majority of mucosal cd4+ t cells express the ccr5 coreceptor, whereasa small fraction of cd4+ t cells in the bloodstream do so.hiv seeks out and destroys ccr5 expressing cd4+ cells during acute infection. a vigorousimmune response eventually controls the infection and initiates the clinically latent phase.however, cd4+ t cells in mucosal tissues remain depleted throughout the infection, althoughenough remain to initially ward off life-threatening infections.continuous hiv replication results in a state of generalized immune activation persistingthroughout the chronic phase. immune activation,

which is reflected by the increased activationstate of immune cells and release of proinflammatory cytokines, results from the activity of severalhiv gene products and the immune response to ongoing hiv replication. another causeis the breakdown of the immune surveillance system of the mucosal barrier caused by thedepletion of mucosal cd4+ t cells during the acute phase of disease.this results in the systemic exposure of the immune system to microbial components of thegut's normal flora, which in a healthy person is kept in check by the mucosal immune system.the activation and proliferation of t cells that results from immune activation providesfresh targets for hiv infection. however, direct killing by hiv alone cannot accountfor the observed depletion of cd4+ t cells

since only 0.01--0.10% of cd4+ t cells inthe blood are infected. a major cause of cd4+ t cell loss appearsto result from their heightened susceptibility to apoptosis when the immune system remainsactivated. although new t cells are continuously produced by the thymus to replace the oneslost, the regenerative capacity of the thymus is slowly destroyed by direct infection ofitsthymocytes by hiv. eventually, the minimal number of cd4+ t cells necessary to maintaina sufficient immune response is lost, leading to aidscells affected the virus, entering through which ever route,acts primarily on the following cells: • lymphoreticular system:• cd4+ t-helper cells

• macrophages• monocytes • b-lymphocytes• certain endothelial cells • central nervous system:• microglia of the nervous system • astrocytes• oligodendrocytes • neurones -- indirectly by the action ofcytokines and the gp-120 the effectthe virus has cytopathic effects but how it does it is still not quite clear. it can remaininactive in these cells for long periods, though. this effect is hypothesized to bedue to the cd4-gp120 interaction. • the most prominent effect of hiv is itst-helper cell suppression and lysis. the cell

is simply killed off or deranged to the pointof being function-less (they do not respond to foreign antigens). the infected b-cellscan not produce enough antibodies either. thus the immune system collapses leading tothe familiar aids complications, like infections and neoplasms (vide supra).• infection of the cells of the cns cause acute aseptic meningitis, subacute encephalitis,vacuolar myelopathy and peripheral neuropathy. later it leads to even aids dementia complex.• the cd4-gp120 interaction (see above) is also permissive to other viruses like cytomegalovirus,hepatitis virus, herpes simplex virus, etc. these viruses lead to further cell damagei. e. cytopathy. molecular basisfor details, see:

• structure and genome of hiv• hiv replication cycle • hiv tropismdiagnosis the diagnosis of aids in a person infectedwith hiv is based on the presence of certain signs or symptoms. since june 5, 1981, manydefinitions have been developed for epidemiological surveillance such as the bangui definitionand the 1994 expanded world health organization aids case definition. however, clinical stagingof patients was not an intended use for these systems as they are neither sensitive, norspecific. in developing countries, the world health organizationstaging system for hivinfection and disease, using clinical and laboratory data, is used and in developedcountries, the centers for disease control

(cdc) classification system is used.who disease staging system main article: who disease staging system forhiv infection and disease in 1990, the world health organization (who)grouped these infections and conditions together by introducing a staging system for patientsinfected with hiv-1.an update took place in september 2005. most of these conditions areopportunistic 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 respiratorytract infections • stage iii: includes unexplained chronicdiarrhea 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 main article: cdc classification system forhiv infection there are two main definitions for aids, bothproduced by the centers for disease control and prevention (cdc). the older definitionis to referring to aids using the diseases that were associated with it, for example,lymphadenopathy, the disease after which the discoverers of hiv originally named the virus.in 1993, the cdc expanded their definition of aids to include all hiv positive peoplewith a cd4+ t cell count below 200 per âµl

of blood or 14% of all lymphocytes. the majorityof new aids cases in developed countries use either this definition or the pre-1993 cdcdefinition. the aids diagnosis still stands even if, after treatment, the cd4+ t cellcount rises to above 200 per âµl of blood or other aids-defining illnesses are cured.hiv test main article: hiv testmany people are unaware that they are infected with hiv. less than 1% of the sexually activeurban population in africa has been tested, and this proportion is even lower in ruralpopulations. furthermore, only 0.5% of pregnant women attending urban health facilities arecounseled, tested or receive their test results. again, this proportion is even lower in ruralhealth facilities. therefore, donor blood

and blood products used in medicine and medicalresearch are screened for hiv. hiv tests are usually performed on venousblood. many laboratories use fourth generation screening tests which detect anti-hiv antibody(igg and igm) and the hiv p24 antigen. the detection of hiv antibody or antigen in apatient previously known to be negative is evidence of hiv infection. individuals whosefirst specimen indicates evidence of hiv infection will have a repeat test on a second bloodsample to confirm the results. the window period (the time between initialinfection and the development of detectable antibodies against the infection) can varysince it can take 3--6 months toseroconvert and to test positive. detection of the virususing polymerase chain reaction (pcr) during

the window period is possible, and evidencesuggests that an infection may often be detected earlier than when using a fourth generationeia screening test. positive results obtained by pcr are confirmedby antibody tests. routinely used hiv tests for infection in neonates and infants (i.e., patients younger than 2 years), born to hiv-positive mothers, have no value becauseof the presence of maternal antibody to hiv in the child's blood. hiv infection can onlybe diagnosed by pcr, testing for hiv pro-viral dna in the children's lymphocytes.prevention estimated per act risk for acquisitionof hiv by exposure route (us only) exposure route estimated infectionsper 10,000 exposures

to an infected sourceblood transfusion 9,000 childbirth (to child) 2,500needle-sharing injection drug use 67 percutaneous needle stick 30receptive anal intercourse* 50 insertive anal intercourse* 6.5receptive penile-vaginal intercourse* 10 insertive penile-vaginal intercourse* 5receptive oral intercourse*⧠1 insertive oral intercourse*⧠0.5* assuming no condom use ⧠source refers to oral intercourseperformed on a man the three main transmission routes of hivare sexual contact, exposure to infected body fluids or tissues, and from mother to fetusor child during perinatal period. it is possible

to find hiv in the saliva, tears, andurineof infected individuals, but there are no recorded cases of infection by these secretions,and the risk of infection is negligible. anti-retroviral treatment of infected patients also significantlyreduces their ability to transmit hiv to others, by reducing the amount of virus in their bodilyfluids to undetectable levels. sexual contactthe majority of hiv infections are acquired through unprotected sexual relations betweenpartners, one of whom has hiv. the primary mode of hiv infection worldwide is throughsexual contact between members of the opposite sex.during a sexual act, only male or female condoms can reduce the risk of infection with hivand other stds. the best evidence to date

indicates that typical condom use reducesthe risk of heterosexual hiv transmission by approximately 80% over the long-term, thoughthe benefit is likely to be higher if condoms are used correctly on every occasion.the male latex condom, if used correctly without oil-based lubricants, is the single most effectiveavailable technology to reduce the sexual transmission of hiv and other sexually transmittedinfections. manufacturers recommend that oil-based lubricants such as petroleum jelly, butter,and lard not be used with latex condoms, because they dissolve the latex, making the condomsporous. if lubrication is desired, manufacturers recommend using water-based lubricants. oil-basedlubricants can be used withpolyurethane condoms. female condoms are commonly made from polyurethane,but are also made from nitrile and latex.

they are larger than male condoms and havea stiffened ring-shaped opening with an inner ring designed to be inserted into the vaginakeeping the condom in place; inserting the female condom requires squeezing this ring.female condoms have been shown to be an important hiv prevention strategy by preliminary studieswhich suggest that overall protected sexual acts increase relative to unprotected sexualacts where female condoms are available. at present, availability of female condoms isvery low and the price remains prohibitive for many women.studies on couples where one partner is infected show that with consistent condom use, hivinfection rates for the uninfected partner are below 1% per year.prevention strategiesare well known in developed countries, but

epidemiological and behavioral studies ineurope and north america suggest that a substantial minority of young people continue to engagein high-risk practices despite hiv/aids knowledge, underestimating their own risk of becominginfected with hiv. randomized controlled trials have shown thatmale circumcision lowers the risk of hiv infection among heterosexual men by up to 60%. it isexpected that this procedure will be actively promoted in many of the countries affectedby hiv, although doing so will involve confronting a number of practical, cultural and attitudinalissues. however, programs to encourage condom use, including providing them free to thosein poverty, are estimated to be 95 times more cost effective than circumcision at reducingthe rate of hiv in sub-saharan africa.

some experts fear that a lower perceptionof vulnerability among circumcised men may result in more sexual risk-taking behavior,thus negating its preventive effects. however, one randomized controlled trial indicatedthat adult male circumcision was not associated with increased hiv risk behavior.studies of hiv infection rates among women who have undergone female genital cutting(fgc) have reported mixed results; for details see female genital cutting.a three-year study in south africa, completed in 2010, found that an anti-microbial vaginalgel could reduce infection rates among women by 50% after one year of use, and by 39% aftertwo and a half years. the results of the study, which was conducted by the centre for theaids programme of research in south africa

(caprisa), were published in science magazinein july 2010, and were then presented at an international aids conference in vienna.body fluid exposure health care workers can reduce exposure tohiv by employing precautions to reduce the risk of exposure to contaminated blood. theseprecautions include barriers such as gloves, masks, protective eyeware or shields, andgowns or aprons which prevent exposure of the skin or mucous membranes to blood bornepathogens. frequent and thorough washing of the skin immediately after being contaminatedwith blood or other bodily fluids can reduce the chance of infection. finally, sharp objectslike needles, scalpels and glass, are carefully disposed of to prevent needlestick injurieswith contaminated items. since intravenous

drug use is an important factor in hiv transmissionin developed countries, harm reduction strategies such as needle-exchange programmes are usedin attempts to reduce the infections caused by drug abuse.mother-to-child current recommendations state that when replacementfeeding, as with a wet nurse, is acceptable, feasible, affordable, sustainable and safe,hiv-infected mothers should avoid breast-feeding their infant. however, if this is not thecase, exclusive breast-feeding is recommended during the first months of life and discontinuedas soon as possible. educationone way to change risky behavior is health education. several studies have shown thepositive impact of education and health literacy

on cautious sex behavior. education worksonly if it leads to higher health literacy and general cognitive ability. this abilityis relevant to understand the relationship between own risky behavior and possible outcomeslike hiv-transmission. in july 2010, a unaids inter-agency task team (iatt) on educationcommissioned literature review found there was a need for more research into non-african(especially non-south african contexts), more research on the actual implementation of sex-educationprogrammes (such as teacher training, access to related services through schools and thecommunity, or parental attitudes to hiv and aids education) and more longitudinal studieson the deeper complexities of the relationship between education and hiv.management

see also hiv treatment and antiretroviraldrug. there is currently no publicly available vaccinefor hiv or cure for hiv or aids. the only known methods of prevention are based on avoidingexposure to the virus or, failing that, an antiretroviral treatment directly after ahighly significant exposure, called post-exposure prophylaxis (pep). pep has a very demandingfour week schedule of dosage. it also has very unpleasant side effects including diarrhea,malaise, nausea and fatigue. antiviral therapy abacavir -- a nucleoside analog reverse transcriptaseinhibitor (narti or nrti) the chemical structure of abacavircurrent treatment for hiv infection consists

of highly active antiretroviral therapy, orhaart. this has been highly beneficial to many hiv-infected individuals since its introductionin 1996 when the protease inhibitor-based haart initially became available. currentoptimal haart options consist of combinations (or "cocktails") consisting of at least threedrugs belonging to at least two types, or "classes, " of antiretroviral agents.typical regimens consist of two nucleoside analogue reverse transcriptase inhibitors(nartis or nrtis) plus either aprotease inhibitor or a non-nucleoside reverse transcriptaseinhibitor (nnrti). because hiv disease progression in children is more rapid than in adults,and laboratory parameters are less predictive of risk for disease progression, particularlyfor young infants, treatment recommendations

are more aggressive for children than foradults. in developed countries where haart is available, doctors assess the viral load,cd4 counts, rapidity of cd4 decline and patient readiness while deciding when to recommendinitiating treatment. traditionally, treatment has been recommended for otherwise asymptomaticpatients when cd4 cell counts fall to 200--250 cells per microliter of blood. however, beginningtreatment earlier (at a cd4 level of 350 cells/microliter) may significantly reduce the risk of death.standard goals of haart include improvement in the patient's quality of life, reductionin complications, and reduction of hiv viremia below the limit of detection, but it doesnot cure the patient of hiv nor does it prevent the return, once treatment is stopped, ofhigh blood levels of hiv, often haart resistant.

moreover, it would take more than the lifetimeof an individual to be cleared of hiv infection using haart.despite this, many hiv-infected individuals have experienced remarkable improvements intheir general health and quality of life, which has led to the plummeting of hiv-associatedmorbidity and mortality. in the absence of haart, progression from hiv infection to aidsoccurs at a median of between nine to ten years and the median survival time after developingaids is only 9.2 months. haart is thought to increase survival time by between 4 and12 years. for some patients, which can be more thanfifty percent of patients, haart achieves far less than optimal results, due to medicationintolerance/side effects, prior ineffective

antiretroviral therapy and infection witha drug-resistant strain of hiv. non-adherence and non-persistence with therapy are the majorreasons why some people do not benefit from haart. the reasons for non-adherence and non-persistenceare varied. major psychosocial issues include poor access to medical care, inadequate socialsupports, psychiatric disease and drug abuse. haart regimens can also be complex and thushard to follow, with large numbers of pills taken frequently.side effects can also deter people from persisting with haart, these include lipodystrophy, dyslipidaemia,diarrhoea, insulin resistance, an increase incardiovascular risks and birth defects.anti-retroviral drugs are expensive, and the majority of the world's infected individualsdo not have access to medications and treatments

for hiv and aids. however, the costs of anti-retroviraldrugs have fallen recently in low-income countries. moreover, patients' quality of life indicesbenefit from anti-retroviral treatment especially if healthcare services are adequate. in theabsence of a cure for aids, anti-retroviral treatment is likely to be a cost-effectivestrategy for enhancing well-being of aids patients and their dependents.complementary and alternative medicine in the us, approximately 60% of hiv patientsuse various forms of complementary or alternative medicine (cam). despite the widespread useof cam by people living with hiv/aids, the effectiveness of these therapies has not beenestablished. a 2005 cochrane review of existing high-quality scientific evidence concluded:"there is insufficient evidence to support

the use of herbal medicines in hiv-infectedindividuals and aids patients. " acupuncture has only been proposed for symptomatic relief,but not to treat or cure hiv or aids. vitamin or mineral supplementation has shownbenefit in some studies. daily doses of selenium can suppress hiv viral burden with an associatedimprovement of the cd4 count. selenium can be used as an adjunct therapy to standardantiviral treatments, but cannot itself cure the infection. more evidence is needed beforeit can be established that selenium supplementation reduces mortality rates. there is some evidencethat vitamin a supplementation in children reduces mortality and improves growth. a largetanzanian trial in immunologically and nutritionally compromised pregnant and lactating women showeda number of benefits to daily multivitamin

supplementation for both mothers and children.dietary intake of micronutrients at rda levels by hiv-infected adults is recommended by theworld health organization (who). the who further states that several studies indicate thatsupplementation of vitamin a, zinc, and iron can produce adverse effects in hiv positiveadults. prognosiswithout treatment, the net median survival time after infection with hiv is estimatedto be 9 to 11 years, depending on the hiv subtype, and the median survival rate afterdiagnosis of aids in resource-limited settings where treatment is not available ranges between6 and 19 months, depending on the study. in areas where it is widely available, the developmentof haart as effective therapy for hiv infection

and aids reduced the death rate from thisdisease by 80%, and raised the life expectancy for a newly diagnosed hiv-infected personto about 20 years. as new treatments continue to be developedand because hiv continues to evolve resistance to treatments, estimates of survival timeare likely to continue to change. without antiretroviral therapy, death normally occurswithin a year after the individual progresses to aids. most patients die from opportunisticinfections or malignancies associated with the progressive failure of the immune system.the rate of clinical disease progression varies widely between individuals and has been shownto be affected by many factors such as host susceptibility and immune function healthcare and co-infections, as well as which particular

strain of the virus is involved.even with anti-retroviral treatment, over the long term hiv-infected patients may experienceneurocognitive disorders, osteoporosis, neuropathy, cancers,nephropathy, and cardiovascular disease.it is not always clear whether these conditions result from the infection, related complications,or are side effects of treatment. the largest cause of aids morbidity today,globally, is tuberculosis co-infection, see aids#pulmonary infections. in africa, hivis the single most important factor contributing to the increase in the incidence of tb since1990. epidemiologymain article: aids pandemic this article is outdated. please update thissection to reflect recent events or newly

available information. (december 2009) estimated prevalence of hiv among young adults(15--49) per country at the end of 2005. estimated number of people living with hiv/aidsby country disability-adjusted life year for hiv andaids per 100,000 inhabitants as of 2004. no data≤ 10 10--2525--50 50--100100--500 500--10001000--2500 2500--50005000--7500

7500-1000010000-50000 ≥ 50000the aids pandemic can also be seen as several epidemics of separate subtypes; the majorfactors in its spread are sexual transmission and vertical transmission from mother to childat birth and through breast milk. despite recent, improved access to antiretroviraltreatment and care in many regions of the world, the aids pandemic claimed an estimated2.1 million (range 1.9--2.4 million) lives in 2007 of which an estimated 330,000 werechildren under 15 years. globally, an estimated 33.2 million people lived with hiv in 2007,including 2.5 million children. an estimated 2.5 million (range 1.8--4.1 million) peoplewere newly infected in 2007, including 420,000

children.sub-saharan africa remains by far the worst affected region. in 2007 it contained an estimated68% of all people living with aids and 76% of all aids deaths, with 1.7 million new infectionsbringing the number of people living with hiv to 22.5 million, and with 11.4 millionaids orphans living in the region. unlike other regions, most people living with hivin sub-saharan africa in 2007 (61%) were women. adult prevalence in 2007 was an estimated5.0%, and aids continued to be the single largest cause of mortality in this region.south africa has the largest population of hiv patients in the world, followed by nigeriaand india. south & south east asia are second worst affected; in 2007 this region containedan estimated 18% of all people living with

aids, and an estimated 300,000 deaths fromaids. india has an estimated 2.5 million infections and an estimated adult prevalence of 0.36%.life expectancy has fallen dramatically in the worst-affected countries; for example,in 2006 it was estimated that it had dropped from 65 to 35 years in botswana.in the united states, young african-american women are also at unusually high risk forhiv infection. african americans make up 10% of the population but about half of the hiv/aidscases nationwide. this is due in part to a lack of information about aids and a perceptionthat they are not vulnerable, as well as to limited access to health-care resources anda higher likelihood of sexual contact with at-risk male sexual partners.there are also geographic disparities in aids

prevalence in the united states, where itis most common in rural areas and in the southern states, particularly in the appalachian andmississippi delta regions and along the border with mexico.approximately 1.1 million personsare living with hiv/aids in the united states, and more than 56,000 new infections occurevery single year. history and originmain article: origin of aids aids was first reported june 5, 1981, whenthe u. s. centers for disease control (cdc) recorded a cluster of pneumocystis cariniipneumonia(now still classified as pcp but known to be caused by pneumocystis jirovecii) in fivehomosexual men inlos angeles. in the beginning, the cdc did not have an official name forthe disease, often referring to it by way

of the diseases that were associated withit, for example, lymphadenopathy, the disease after which the discoverers of hiv originallynamed the virus. they also used kaposi's sarcoma and opportunistic infections, the name bywhich a task force had been set up in 1981. in the general press, the term grid, whichstood for gay-related immune deficiency, had been coined. the cdc, in search of a name,and looking at the infected communities coined "the 4h disease, " as it seemed to singleout haitians,homosexuals, hemophiliacs, and heroin users. however, after determining thataids was not isolated to the gay community, the term grid became misleading and aids wasintroduced at a meeting in july 1982. by september 1982 the cdc started using the name aids,and properly defined the illness.

the earliest known positive identificationof the hiv-1 virus comes from the congo in 1959 and 1960 though genetic studies indicatethat it passed into the human population from chimpanzees around fifty years earlier. arecent study states that a strain of hiv-1 probably moved from africa to haiti and thenentered the united states around 1969. the hiv virus descends from the related simianimmunodeficiency virus (siv), which infects apes and monkeys in africa. there is evidencethat humans who participate in bushmeat activities, either as hunters or as bushmeat vendors,commonly acquire siv. however, only a few of these infections were able to cause epidemicsin humans, and all did so in the late 19th—early 20th century. to explain why hiv became epidemiconly by that time, there are several theories,

each invoking specific driving factors thatmay have promoted siv adaptation to humans, or initial spread: social changes followingcolonialism, rapid transmission ofsiv through unsafe or unsterile injections (that is, injectionsin which the needle is reused without being sterilised), colonial abuses and unsafe smallpoxvaccinationsor injections, or prostitution and the concomitant high frequency of genital ulcer diseases (suchas syphilis) in nascent colonial cities. see the main article origin of aids.one of the first high profile victims of aids was the american actor rock hudson, a knownhomosexual who had been married and divorced earlier in life, who died on 2 october 1985having announced that he was suffering from the virus on 25 july that year. it had beendiagnosed during 1984. a notable british casualty

of aids that year was nicholas eden, a memberof parliament and son of the late prime minister anthony eden. eden junior, a lifelong bachelor,was also a known homosexual. the virus claimed perhaps its most famous victim yet on 24 november1991, when british rock star freddie mercury, lead singer of the bandqueen, died from anaids related illness having only announced that he was suffering from the illness theprevious day. however he had been diagnosed as hiv positive during 1987. one of the firsthigh profile heterosexual victims of the virus was arthur ashe, the american tennis player.he was diagnosed as hiv positive on 31 august 1988, having contracted the virus from bloodtransfusions during heart surgery earlier in the 1980s. further tests within 24 hoursof the initial diagnosis revealed that ashe

had aids, but he did not tell the public abouthis diagnosis until april 1992. he died, aged 49, as a result of the aids virus on 6 february1993. a more controversial theory known as the opvaids hypothesis suggests that the aids epidemic was inadvertently started in the late 1950sin the belgian congo byhilary koprowski's research into a poliomyelitis vaccine.according to scientific consensus, this scenario is not supported by the available evidence.society and culture stigma ryan white became aposter child for hiv afterbeing expelled from school because of his infection.main article: discrimination against people

with hiv/aidsaids stigma exists around the world in a variety of ways, including ostracism, rejection, discriminationand avoidance of hiv infected people; compulsory hiv testing without prior consent or protectionof confidentiality; violence against hiv infected individuals or people who are perceived tobe infected with hiv; and the quarantine of hiv infected individuals. stigma-related violenceor the fear of violence prevents many people from seeking hiv testing, returning for theirresults, or securing treatment, possibly turning what could be a manageable chronic illnessinto 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 likelyto be associated with any deadly and transmissible illness.• symbolic aids stigma—the use of hiv/aids to express attitudes toward the social groupsor lifestyles perceived to be associated with the disease.• courtesy aids stigma—stigmatization of people connected to the issue of hiv/aidsor hiv- positive people. often, aids stigma is expressed in conjunctionwith one or more other stigmas, particularly those associated with homosexuality,bisexuality,promiscuity, prostitution, and intravenous drug use.in many developed countries, there is an association between aids and homosexuality or bisexuality,and this association is correlated with higher

levels of sexual prejudice such as anti-homosexualattitudes. there is also a perceived association between aids and all male-male sexual behavior,including sex between uninfected men. economic impactmain article: economic impact of aids changes in life expectancy in some hard-hitafrican countries. botswana zimbabwe kenya south africa ugandahiv and aids affects economic growth by reducing the availability of human capital. withoutproper nutrition, health care and medicine that is available in developed countries,large numbers of people suffer and die from aids-related complications. they will notonly be unable to work, but will also require significant medical care. the forecast isthat this will probably cause a collapse of

economies and societies in countries witha significant aids population. in some heavily infected areas, the epidemic has left behindmany orphans cared for by elderly grandparents. the increased mortality has results in a smallerskilled population and labor force. this smaller labor force consists of increasingly youngerpeople, with reduced knowledge and work experience leading to reduced productivity. an increasein workers' time off to look after sick family members or for sick leave lowers productivity.increased mortality reduces the mechanisms that generate human capital and investmentin people, through loss of income and the death of parents.by affecting mainly young adults, aids reduces the taxable population, in turn reducing theresources available for public expenditures

such as education and health services notrelated to aids resulting in increasing pressure for the state's finances and slower growthof the economy. this results in a slower growth of the tax base, an effect that is reinforcedif there are growing expenditures on treating the sick, training (to replace sick workers),sick pay and caring for aids orphans. this is especially true if the sharp increase inadult mortality shifts the responsibility and blame from the family to the governmentin caring for these orphans. on the level of the household, aids resultsin both the loss of income and increased spending on healthcare by the household. the incomeeffects of this lead to spending reduction as well as a substitution effect away fromeducation and towards healthcare and funeral

spending. a study in cã´te d'ivoire showedthat households with an hiv/aids patient spent twice as much on medical expenses as otherhouseholds. religion and aidsmain article: religion and aids the topic of religion and aids has becomehighly controversial in the past twenty years, primarily because many prominent religiousleaders have publicly declared their opposition to the use of condoms, which scientists feelis currently the only means of stopping the epidemic. however, there is a growing opennessto faith-based methods due to the failure rates associated with condoms. other issuesinvolve religious participation in global health care services and collaboration withsecular organizations such as unaids and the

world health organization.the religious approach to prevent the spread of aids according to a report by americanhealth expert matthew hanley titled the catholic church and the global aids crisis argues thatcultural changes are needed including a re-emphasis on fidelity within marriage and sexual abstinenceoutside of it. aids denialismmain article: aids denialism a small number of activists question the connectionbetween hiv and aids, the existence of hiv, or the validity of current treatment methods(even going so far as to claim that the drug therapy itself was the cause of aids deaths).though these claims have been examined and thoroughly rejected by the scientific community,they continue to be promulgated through the

internet and have had a significant politicalimpact. in south africa, former president thabo mbeki'sembrace of aids denialism resultedin an ineffective governmental response to the aids epidemic that has been blamed forhundreds of thousands of aids-related deaths. kgb disinformationmain article: operation infektion operation infektion was a worldwide sovietactive measures operation to spread information that the united states had created hiv/aids.surveys show that a significant number of people believed -- and continue to believe-- in such claims. government reactionthe examples and perspective in this article may not represent a worldwide view of thesubject. please improve this article and discuss

the issue on the talk page. (december 2010)in 2010, former us president bill clinton said that countries receiving aid to combatthe epidemic should redirect funding to local organizations who could spend it most effectivelyand efficiently. he said, "in too many countries, too much money goesto pay for too many people to go to too many meetings, get on too many airplanes. "research directions "aids research" redirects here. for the journalformerly known as aids research, see aids research and human retroviruses.it has been postulated that only a vaccine can halt the pandemic because a vaccine wouldpossibly cost less, thus being affordable for developing countries, and would not requiredaily treatments. however, even after almost

30 years of research, hiv-1 remains a difficulttarget for a vaccine. research to improve current treatments includesdecreasing side effects of current drugs, further simplifying drug regimens to improveadherence, and determining the best sequence of regimens to manage drug resistance. a numberof studies have shown that measures to prevent opportunistic infections can be beneficialwhen treating patients with hiv infection or aids. vaccination against hepatitis a andb is advised for patients who are not infected with these viruses and are at risk of becominginfected. patients with substantial immunosuppression are also advised to receive prophylactic therapyfor pneumocystis jiroveci pneumonia (pcp), and many patients may benefit from prophylactictherapy for toxoplasmosis and cryptococcus

meningitis as well.researchers have discovered an abzyme that can destroy the protein gp120 cd4 bindingsite. this protein is common to all hiv variants as it is the attachment point for b lymphocytesand subsequent compromising of the immune system.researchers from the hebrew university of jerusalem have also discovered that a combinationof peptides that stimulate integration together with the protease inhibitor ro 31-8959 causedapoptotic cell death of hiv-infected cells with total extermination of the virus butdid not harm healthy cells. it could take several years before a commercial treatmentbased on this discovery becomes available. reactivation of the retrocyclin pseudogenehas been proposed as a possible prevention

method, as was demonstrated in a proof-of-conceptstudy in tissue culture cells. in berlin, germany, a 42-year-old leukemiapatient, timothy ray brown (also referred to as the "berlin patient"), infected withhiv for more than a decade was given an experimental transplant of bone marrow with cells thatcontained an unusual natural variant of the ccr5 cell-surface receptor. this ccr5-î”32variant has been shown to make some cells from people who are born with it resistantto infection with some strains of hiv. almost two years after the transplant, and even afterthe patient reportedly stopped taking antiretroviral medications, hiv has not been detected inthe patient's blood. as of december 2010, three years after the transplant, brown wasstill free of any detectable hiv in his blood

and was described, in a paper in the journalblood, as "cured. "