AIDS

AIDS

Overview


Acquired immune deficiency syndrome or acquired immunodeficiency syndrome (AIDS) is a disease of the human immune system
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...

 caused by the human immunodeficiency virus
HIV
Human immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive...

 (HIV). The illness interferes with the immune system making people with AIDS much more likely to get infections, including opportunistic infections and tumors that do not affect people with working immune systems. This susceptibility gets worse as the disease continues.

HIV is transmitted
Transmission (medicine)
In medicine and biology, transmission is the passing of a communicable disease from an infected host individual or group to a conspecific individual or group, regardless of whether the other individual was previously infected...

 in many ways, such as anal
Anal sex
Anal sex is the sex act in which the penis is inserted into the anus of a sexual partner. The term can also include other sexual acts involving the anus, including pegging, anilingus , fingering, and object insertion.Common misconception describes anal sex as practiced almost exclusively by gay men...

, vaginal
Sexual intercourse
Sexual intercourse, also known as copulation or coitus, commonly refers to the act in which a male's penis enters a female's vagina for the purposes of sexual pleasure or reproduction. The entities may be of opposite sexes, or they may be hermaphroditic, as is the case with snails...

 or oral
Oral sex
Oral sex is sexual activity involving the stimulation of the genitalia of a sex partner by the use of the mouth, tongue, teeth or throat. Cunnilingus refers to oral sex performed on females while fellatio refer to oral sex performed on males. Anilingus refers to oral stimulation of a person's anus...

 sex
Sexual intercourse
Sexual intercourse, also known as copulation or coitus, commonly refers to the act in which a male's penis enters a female's vagina for the purposes of sexual pleasure or reproduction. The entities may be of opposite sexes, or they may be hermaphroditic, as is the case with snails...

, blood transfusion
Blood transfusion
Blood transfusion is the process of receiving blood products into one's circulation intravenously. Transfusions are used in a variety of medical conditions to replace lost components of the blood...

, contaminated hypodermic needle
Hypodermic needle
A hypodermic needle is a hollow needle commonly used with a syringe to inject substances into the body or extract fluids from it...

s, exchange between mother and baby during pregnancy
Pregnancy
Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...

, childbirth
Childbirth
Childbirth is the culmination of a human pregnancy or gestation period with the birth of one or more newborn infants from a woman's uterus...

, and breastfeeding
Breastfeeding
Breastfeeding is the feeding of an infant or young child with breast milk directly from female human breasts rather than from a baby bottle or other container. Babies have a sucking reflex that enables them to suck and swallow milk. It is recommended that mothers breastfeed for six months or...

.
Discussion
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Recent Discussions
Quotations

In the end one cannot avoid the conclusion that AIDS unites certain human themes — homosexuality, sexual disease, and death — about which society actively resists enlightenment. These are things that we are unwilling to address or even think about. We don't want to understand them. We would rather fear them.

Martin Amis, "Making Sense of AIDS" (1985), in The Moronic Inferno and Other Visits to America (1986)

As individual and unpredictable as this illness seems to be, the one thing I found I could say with certainty was this: AIDS makes things more intensely what they already are.

Mark Doty|Mark Doty Heaven’s Cost

On December 22,1986, finding I was body positive, I set myself a target: I would disclose my secret and survive Margaret Thatcher. I did. Now I have set my sights on the millennium and a world where we are all equal.

Derek Jarman At Your Own Risk

There are many who wish to believe that premarital sex causes venereal diseases, that homosexuality causes AIDS... This is simply not true; infectious diseases are caused by infectious agents.

P. Skrabanek, "Preventive Medicine and Morality," Lancet 1 (8473)(1986): 143.
Encyclopedia
List of abbreviations used in this article

AIDS: Acquired immune deficiency syndrome

HIV: Human immunodeficiency virus
HIV
Human immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive...



CD4+: CD4+ T helper cells
T helper cell
T helper cells are a sub-group of lymphocytes, a type of white blood cell, that play an important role in the immune system, particularly in the adaptive immune system. These cells have no cytotoxic or phagocytic activity; they cannot kill infected host cells or pathogens. Rather, they help other...

 

CCR5: Chemokine (C-C motif) receptor 5
CCR5
C-C chemokine receptor type 5, also known as CCR5, is a protein that in humans is encoded by the CCR5 gene. CCR5 is a member of the beta chemokine receptors family of integral membrane proteins...



CDC: Centers for Disease Control and Prevention
Centers for Disease Control and Prevention
The Centers for Disease Control and Prevention are a United States federal agency under the Department of Health and Human Services headquartered in Druid Hills, unincorporated DeKalb County, Georgia, in Greater Atlanta...



WHO: World Health Organization
World Health Organization
The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...



PCP: Pneumocystis pneumonia
Pneumocystis pneumonia
Pneumocystis pneumonia or pneumocystosis is a form of pneumonia, caused by the yeast-like fungus Pneumocystis jirovecii...



TB: Tuberculosis
Tuberculosis
Tuberculosis, MTB, or TB is a common, and in many cases lethal, infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis. Tuberculosis usually attacks the lungs but can also affect other parts of the body...



MTCT: Mother-to-child transmission

HAART: Highly active antiretroviral therapy
Antiretroviral drug
Antiretroviral drugs are medications for the treatment of infection by retroviruses, primarily HIV. When several such drugs, typically three or four, are taken in combination, the approach is known as Highly Active Antiretroviral Therapy, or HAART...



STI/STD: Sexually transmitted infection
Sexually transmitted disease
Sexually transmitted disease , also known as a sexually transmitted infection or venereal disease , is an illness that has a significant probability of transmission between humans by means of human sexual behavior, including vaginal intercourse, oral sex, and anal sex...

/disease


Acquired immune deficiency syndrome or acquired immunodeficiency syndrome (AIDS) is a disease of the human immune system
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...

 caused by the human immunodeficiency virus
HIV
Human immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive...

 (HIV). The illness interferes with the immune system making people with AIDS much more likely to get infections, including opportunistic infections and tumors that do not affect people with working immune systems. This susceptibility gets worse as the disease continues.

HIV is transmitted
Transmission (medicine)
In medicine and biology, transmission is the passing of a communicable disease from an infected host individual or group to a conspecific individual or group, regardless of whether the other individual was previously infected...

 in many ways, such as anal
Anal sex
Anal sex is the sex act in which the penis is inserted into the anus of a sexual partner. The term can also include other sexual acts involving the anus, including pegging, anilingus , fingering, and object insertion.Common misconception describes anal sex as practiced almost exclusively by gay men...

, vaginal
Sexual intercourse
Sexual intercourse, also known as copulation or coitus, commonly refers to the act in which a male's penis enters a female's vagina for the purposes of sexual pleasure or reproduction. The entities may be of opposite sexes, or they may be hermaphroditic, as is the case with snails...

 or oral
Oral sex
Oral sex is sexual activity involving the stimulation of the genitalia of a sex partner by the use of the mouth, tongue, teeth or throat. Cunnilingus refers to oral sex performed on females while fellatio refer to oral sex performed on males. Anilingus refers to oral stimulation of a person's anus...

 sex
Sexual intercourse
Sexual intercourse, also known as copulation or coitus, commonly refers to the act in which a male's penis enters a female's vagina for the purposes of sexual pleasure or reproduction. The entities may be of opposite sexes, or they may be hermaphroditic, as is the case with snails...

, blood transfusion
Blood transfusion
Blood transfusion is the process of receiving blood products into one's circulation intravenously. Transfusions are used in a variety of medical conditions to replace lost components of the blood...

, contaminated hypodermic needle
Hypodermic needle
A hypodermic needle is a hollow needle commonly used with a syringe to inject substances into the body or extract fluids from it...

s, exchange between mother and baby during pregnancy
Pregnancy
Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...

, childbirth
Childbirth
Childbirth is the culmination of a human pregnancy or gestation period with the birth of one or more newborn infants from a woman's uterus...

, and breastfeeding
Breastfeeding
Breastfeeding is the feeding of an infant or young child with breast milk directly from female human breasts rather than from a baby bottle or other container. Babies have a sucking reflex that enables them to suck and swallow milk. It is recommended that mothers breastfeed for six months or...

. It can be transmitted by any contact of a mucous membrane
Mucous membrane
The mucous membranes are linings of mostly endodermal origin, covered in epithelium, which are involved in absorption and secretion. They line cavities that are exposed to the external environment and internal organs...

 or the bloodstream with a bodily fluid that has the virus in it, such as the blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

, semen
Semen
Semen is an organic fluid, also known as seminal fluid, that may contain spermatozoa. It is secreted by the gonads and other sexual organs of male or hermaphroditic animals and can fertilize female ova...

, vaginal fluid
Vaginal lubrication
Vaginal lubrication is a lubricating fluid that is naturally produced in a woman's vagina. Vaginal lubrication or moistness is present at all times, but production increases significantly during a woman's sexual arousal in anticipation of sexual intercourse...

, preseminal fluid
Pre-ejaculate
Pre-ejaculate is the clear, colorless, viscous fluid that emits from the urethra of a man's penis when he is sexually aroused. It is similar in composition to semen, but has some significant chemical differences...

, or breast milk from an infected person.

The virus and disease are often referred to together as HIV/AIDS. The disease is a major health problem in many parts of the world, and is considered a pandemic
Pandemic
A pandemic is an epidemic of infectious disease that is spreading through human populations across a large region; for instance multiple continents, or even worldwide. A widespread endemic disease that is stable in terms of how many people are getting sick from it is not a pandemic...

, a disease outbreak that is not only present over a large area but is actively spreading. In 2009, the World Health Organization
World Health Organization
The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...

 (WHO) estimated that there are 33.4 million people worldwide living with HIV/AIDS, with 2.7 million new HIV infections per year and 2.0 million annual deaths due to AIDS. In 2007, UNAIDS
Joint United Nations Programme on HIV/AIDS
The Joint United Nations Programme on HIV and AIDS, or UNAIDS, is the main advocate for accelerated, comprehensive and coordinated global action on the HIV epidemic....

 estimated: 33.2 million people worldwide had AIDS that year; AIDS killed 2.1 million people in the course of that year, including 330,000 children, and 76% of those deaths occurred in sub-Saharan Africa
Sub-Saharan Africa
Sub-Saharan Africa as a geographical term refers to the area of the African continent which lies south of the Sahara. A political definition of Sub-Saharan Africa, instead, covers all African countries which are fully or partially located south of the Sahara...

. According to UNAIDS 2009 report, worldwide some 60 million people have been infected since the start of the pandemic, with some 25 million deaths, and 14 million orphaned children in southern Africa alone.

Genetic research indicates that HIV originated in west-central Africa during the late nineteenth or early twentieth century. AIDS was first recognized by the U. S. Centers for Disease Control and Prevention
Centers for Disease Control and Prevention
The Centers for Disease Control and Prevention are a United States federal agency under the Department of Health and Human Services headquartered in Druid Hills, unincorporated DeKalb County, Georgia, in Greater Atlanta...

 in 1981 and its cause, HIV, identified in the early 1980s.

Although treatments for HIV/AIDS can slow the course of the disease, there is no known cure or HIV vaccine
HIV vaccine
An HIV vaccine that protects vaccinated individuals from HIV infection is the goal of many HIV research programmes. Currently, there is no effective vaccine against HIV, the virus that causes AIDS...

. Antiretroviral
Antiretroviral drug
Antiretroviral drugs are medications for the treatment of infection by retroviruses, primarily HIV. When several such drugs, typically three or four, are taken in combination, the approach is known as Highly Active Antiretroviral Therapy, or HAART...

 treatment reduces both the deaths
Mortality rate
Mortality rate is a measure of the number of deaths in a population, scaled to the size of that population, per unit time...

 and new infections from HIV/AIDS, but these drugs are expensive and the medications are not available in all countries. Due to the difficulty in treating HIV infection, preventing infection is a key aim in controlling the AIDS pandemic
AIDS pandemic
The acquired immune deficiency syndrome pandemic is a widespread disease caused by the human immunodeficiency virus .Since AIDS was first recognized in 1981, it has led to the deaths of more than 25 million people, making it one of the most destructive diseases in recorded history.Despite recent...

, with health organizations promoting safe sex
Safe sex
Safe sex is sexual activity engaged in by people who have taken precautions to protect themselves against sexually transmitted diseases such as AIDS. It is also referred to as safer sex or protected sex, while unsafe or unprotected sex is sexual activity engaged in without precautions...

 and needle-exchange programme
Needle-exchange programme
A Needle & syringe programme or syringe-exchange programme is a social policy based on the philosophy of harm reduction where injecting drug users can obtain hypodermic needles and associated injection equipment at little or no cost. Many programmes are called "exchanges" because some require...

s in attempts to slow the spread of the virus.

Signs and symptoms




The symptoms of AIDS are primarily the result of conditions that do not normally develop in individuals with healthy immune system
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...

s. Most of these conditions are infections caused by bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

, virus
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...

es, fungi
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...

 and parasite
Parasitism
Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites...

s that are normally controlled by the elements of the immune system that HIV damages.

Opportunistic infection
Opportunistic infection
An opportunistic infection is an infection caused by pathogens, particularly opportunistic pathogens—those that take advantage of certain situations—such as bacterial, viral, fungal or protozoan infections that usually do not cause disease in a healthy host, one with a healthy immune system...

s are common in people with AIDS. These infections affect nearly every organ system
Biological system
In biology, a biological system is a group of organs that work together to perform a certain task. Common systems, such as those present in mammals and other animals, seen in human anatomy, are those such as the circulatory system, the respiratory system, the nervous system, etc.A group of systems...

.

People with AIDS also have an increased risk of developing various cancers such as Kaposi's sarcoma
Kaposi's sarcoma
Kaposi's sarcoma is a tumor caused by Human herpesvirus 8 , also known as Kaposi's sarcoma-associated herpesvirus . It was originally described by Moritz Kaposi , a Hungarian dermatologist practicing at the University of Vienna in 1872. It became more widely known as one of the AIDS defining...

, cervical cancer
Cervical cancer
Cervical cancer is malignant neoplasm of the cervix uteri or cervical area. One of the most common symptoms is abnormal vaginal bleeding, but in some cases there may be no obvious symptoms until the cancer is in its advanced stages...

 and cancers of the immune system known as lymphoma
Lymphoma
Lymphoma is a cancer in the lymphatic cells of the immune system. Typically, lymphomas present as a solid tumor of lymphoid cells. Treatment might involve chemotherapy and in some cases radiotherapy and/or bone marrow transplantation, and can be curable depending on the histology, type, and stage...

s. Additionally, people with AIDS often have systemic symptoms of infection like fever
Fever
Fever is a common medical sign characterized by an elevation of temperature above the normal range of due to an increase in the body temperature regulatory set-point. This increase in set-point triggers increased muscle tone and shivering.As a person's temperature increases, there is, in...

s, sweats (particularly at night), swollen glands, chills, weakness, and weight loss
Weight loss
Weight loss, in the context of medicine, health or physical fitness, is a reduction of the total body mass, due to a mean loss of fluid, body fat or adipose tissue and/or lean mass, namely bone mineral deposits, muscle, tendon and other connective tissue...

. The specific opportunistic infections that AIDS patients develop depend in part on the prevalence of these infections in the geographic area in which the patient lives.

Pulmonary


Pneumocystis pneumonia (originally known as Pneumocystis carinii pneumonia, and still abbreviated as PCP, which now stands for Pneumocystis pneumonia) is relatively rare in healthy, immunocompetent
Immunocompetence
Immunocompetence is the ability of the body to produce a normal immune response following exposure to an antigen. Immunocompetence is the opposite of immunodeficiency or immuno-incompetent or immuno-compromised...

 people, but common among HIV-infected individuals. It is caused by Pneumocystis jirovecii.

Before the advent of effective diagnosis, treatment and routine prophylaxis
Preventive medicine
Preventive medicine or preventive care refers to measures taken to prevent diseases, rather than curing them or treating their symptoms...

 in Western countries, it was a common immediate cause of death. In developing countries, it is still one of the first indications of AIDS in untested individuals, although it does not generally occur unless the CD4 count is less than 200 cells per µL of blood.

Tuberculosis
Tuberculosis
Tuberculosis, MTB, or TB is a common, and in many cases lethal, infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis. Tuberculosis usually attacks the lungs but can also affect other parts of the body...

 (TB) is unique among infections associated with HIV because it is transmissible to immunocompetent people via the respiratory route, and is not easily treatable once identified. Multidrug resistance is a serious problem. Tuberculosis
Tuberculosis
Tuberculosis, MTB, or TB is a common, and in many cases lethal, infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis. Tuberculosis usually attacks the lungs but can also affect other parts of the body...

 with HIV
HIV
Human immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive...

 co-infection (TB/HIV) is a major world health problem according to the World Health Organization
World Health Organization
The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...

: in 2007, 456,000 deaths among incident TB cases were HIV-positive, a third of all TB deaths and nearly a quarter of the estimated 2 million HIV deaths in that year. Even though its incidence has declined because of the use of directly observed therapy and other improved practices in Western countries, this is not the case in developing countries where HIV is most prevalent. In early-stage HIV infection (CD4 count >300 cells per µL), TB typically presents as 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 localized to one particular site, often affecting bone marrow
Bone marrow
Bone marrow is the flexible tissue found in the interior of bones. In humans, bone marrow in large bones produces new blood cells. On average, bone marrow constitutes 4% of the total body mass of humans; in adults weighing 65 kg , bone marrow accounts for approximately 2.6 kg...

, bone
Bone
Bones are rigid organs that constitute part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue...

, urinary and gastrointestinal tracts, liver
Liver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...

, regional lymph node
Lymph node
A lymph node is a small ball or an oval-shaped organ of the immune system, distributed widely throughout the body including the armpit and stomach/gut and linked by lymphatic vessels. Lymph nodes are garrisons of B, T, and other immune cells. Lymph nodes are found all through the body, and act as...

s, and the central nervous system
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...

.

Gastrointestinal


Esophagitis
Esophagitis
Esophagitis is inflammation of the esophagus. It may be acute or chronic. The acute esophagitis can be catarrhal or phlegmonous, whereas the chronic esophagitis may be hypertrophic or atrophic.-Infectious:...

 is an inflammation of the lining of the lower end of the esophagus
Esophagus
The esophagus is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. During swallowing, food passes from the mouth through the pharynx into the esophagus and travels via peristalsis to the stomach...

 (gullet or swallowing tube leading to the stomach
Stomach
The stomach is a muscular, hollow, dilated part of the alimentary canal which functions as an important organ of the digestive tract in some animals, including vertebrates, echinoderms, insects , and molluscs. It is involved in the second phase of digestion, following mastication .The stomach is...

). In HIV-infected individuals, this is normally due to fungal (candidiasis
Candidiasis
Thrush redirects here. For the hoof infection see Thrush .Candidiasis or thrush is a fungal infection of any of the Candida species , of which Candida albicans is the most common...

) or viral (herpes simplex-1
Herpes simplex virus
Herpes simplex virus 1 and 2 , also known as Human herpes virus 1 and 2 , are two members of the herpes virus family, Herpesviridae, that infect humans. Both HSV-1 and HSV-2 are ubiquitous and contagious...

 or cytomegalovirus
Cytomegalovirus
Cytomegalovirus is a viral genus of the viral group known as Herpesviridae or herpesviruses. It is typically abbreviated as CMV: The species that infects humans is commonly known as human CMV or human herpesvirus-5 , and is the most studied of all cytomegaloviruses...

) infections. In rare cases, it could be due to mycobacteria
Mycobacterium
Mycobacterium is a genus of Actinobacteria, given its own family, the Mycobacteriaceae. The genus includes pathogens known to cause serious diseases in mammals, including tuberculosis and leprosy...

.

Unexplained chronic diarrhea
Diarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...

 in HIV infection is due to many possible causes, including common bacterial (Salmonella
Salmonella
Salmonella is a genus of rod-shaped, Gram-negative, non-spore-forming, predominantly motile enterobacteria with diameters around 0.7 to 1.5 µm, lengths from 2 to 5 µm, and flagella which grade in all directions . They are chemoorganotrophs, obtaining their energy from oxidation and reduction...

, Shigella
Shigella
Shigella is a genus of Gram-negative, nonspore forming, non-motile, rod-shaped bacteria closely related to Escherichia coli and Salmonella. The causative agent of human shigellosis, Shigella causes disease in primates, but not in other mammals. It is only naturally found in humans and apes. During...

, Listeria or Campylobacter
Campylobacter
Campylobacter is a genus of bacteria that are Gram-negative, spiral, and microaerophilic. Motile, with either unipolar or bipolar flagella, the organisms have a characteristic spiral/corkscrew appearance and are oxidase-positive. Campylobacter jejuni is now recognized as one of the main causes...

) and parasitic infections; and uncommon opportunistic infections such as cryptosporidiosis
Cryptosporidiosis
Cryptosporidiosis, also known as crypto, is a parasitic disease caused by Cryptosporidium, a protozoan parasite in the phylum Apicomplexa. It affects the intestines of mammals and is typically an acute short-term infection...

, microsporidiosis
Microsporidiosis
Microspridiosis is an opportunistic intestinal infection that causes diarrhea and wasting in immunocompromised individuals . It results from different species of microsporidia, a group of microbial fungi....

, Mycobacterium avium
Mycobacterium avium-intracellulare infection
Mycobacterium avium-intracellulare is an atypical mycobacterial infection which can occur in the later stages of AIDS. It can also affect people who do not have AIDS and usually first presents as a persistent cough. Additionally, cases in elderly men have increased recently...

 complex (MAC) and viruses, astrovirus
Astrovirus
Astrovirus is a type of virus that was first discovered in 1975 using electron microscopes following an outbreak of diarrhoea in humans. In addition to humans, astroviruses have now been isolated from numerous mammalian animal species and from avian species such as ducks, chickens, and turkey...

, adenovirus
Adenoviridae
Adenoviruses are medium-sized , nonenveloped icosahedral viruses composed of a nucleocapsid and a double-stranded linear DNA genome...

, rotavirus
Rotavirus
Rotavirus is the most common cause of severe diarrhoea among infants and young children, and is one of several viruses that cause infections often called stomach flu, despite having no relation to influenza. It is a genus of double-stranded RNA virus in the family Reoviridae. By the age of five,...

 and cytomegalovirus
Cytomegalovirus
Cytomegalovirus is a viral genus of the viral group known as Herpesviridae or herpesviruses. It is typically abbreviated as CMV: The species that infects humans is commonly known as human CMV or human herpesvirus-5 , and is the most studied of all cytomegaloviruses...

, (the latter as a course of colitis
Colitis
In medicine, colitis refers to an inflammation of the colon and is often used to describe an inflammation of the large intestine .Colitides may be acute and self-limited or chronic, i.e...

).

In some cases, diarrhea may be a side effect of several drugs used to treat HIV, or it may simply accompany HIV infection, particularly during primary HIV infection. It may also be a side effect of antibiotics used to treat bacterial causes of diarrhea (common for Clostridium difficile
Clostridium difficile
Clostridium difficile , also known as "CDF/cdf", or "C...

). In the later stages of HIV infection, diarrhea is thought to be a reflection of changes in the way the intestinal tract absorbs nutrients, and may be an important component of HIV-related wasting
Wasting
In medicine, wasting refers to the process by which a debilitating disease causes muscle and fat tissue to "waste" away. Wasting is sometimes referred to as "acute malnutrition" because it is believed that episodes of wasting have a short duration, in contrast to stunting, which is regarded as...

.

Neurological and psychiatric


HIV infection may lead to a variety of neuropsychiatric sequela
Sequela
A sequela) is a pathological condition resulting from a disease, injury, or other trauma.Chronic kidney disease, for example, is sometimes a sequela of diabetes, and neck pain is a common sequela of whiplash or other trauma to the cervical vertebrae. Post-traumatic stress disorder may be a...

e, either by infection of the now susceptible nervous system by organisms, or as a direct consequence of the illness itself.

Toxoplasmosis
Toxoplasmosis
Toxoplasmosis is a parasitic disease caused by the protozoan Toxoplasma gondii. The parasite infects most genera of warm-blooded animals, including humans, but the primary host is the felid family. Animals are infected by eating infected meat, by ingestion of feces of a cat that has itself...

 is a disease caused by the single-celled parasite
Parasitism
Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites...

 called Toxoplasma gondii; it usually infects the brain, causing toxoplasma encephalitis
Encephalitis
Encephalitis is an acute inflammation of the brain. Encephalitis with meningitis is known as meningoencephalitis. Symptoms include headache, fever, confusion, drowsiness, and fatigue...

, but it can also infect and cause disease in the eye
Human eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...

s and lungs. Cryptococcal meningitis is an infection of the meninx
Meninges
The meninges is the system of membranes which envelopes the central nervous system. The meninges consist of three layers: the dura mater, the arachnoid mater, and the pia mater. The primary function of the meninges and of the cerebrospinal fluid is to protect the central nervous system.-Dura...

 (the membrane covering the brain and spinal cord
Spinal cord
The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain . The brain and spinal cord together make up the central nervous system...

) by the fungus Cryptococcus neoformans
Cryptococcus neoformans
Cryptococcus neoformans is an encapsulated yeast that can live in both plants and animals. Its teleomorph is Filobasidiella neoformans, a filamentous fungus belonging to the class Tremellomycetes. It is often found in pigeon excrement....

. It can cause fevers, headache
Headache
A headache or cephalalgia is pain anywhere in the region of the head or neck. It can be a symptom of a number of different conditions of the head and neck. The brain tissue itself is not sensitive to pain because it lacks pain receptors. Rather, the pain is caused by disturbance of the...

, fatigue, nausea
Nausea
Nausea , is a sensation of unease and discomfort in the upper stomach with an involuntary urge to vomit. It often, but not always, precedes vomiting...

, and vomiting
Vomiting
Vomiting is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose...

. Patients may also develop seizures and confusion; left untreated, it can be lethal.

Progressive multifocal leukoencephalopathy
Progressive multifocal leukoencephalopathy
Progressive multifocal leukoencephalopathy , also known as progressive multifocal leukoencephalitis, is a rare and usually fatal viral disease that is characterized by progressive damage or inflammation of the white matter of the brain at multiple locations .It occurs almost exclusively in...

 (PML) is a demyelinating disease
Demyelinating disease
A demyelinating disease is any disease of the nervous system in which the myelin sheath of neurons is damaged. This impairs the conduction of signals in the affected nerves, causing impairment in sensation, movement, cognition, or other functions depending on which nerves are involved.The term...

, in which the gradual destruction of the myelin
Myelin
Myelin is a dielectric material that forms a layer, the myelin sheath, usually around only the axon of a neuron. It is essential for the proper functioning of the nervous system. Myelin is an outgrowth of a type of glial cell. The production of the myelin sheath is called myelination...

 sheath covering the axon
Axon
An axon is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body or soma....

s of nerve cells impairs the transmission of nerve impulses. It is caused by a virus called JC virus
JC virus
The JC virus or John Cunningham virus is a type of human polyomavirus and is genetically similar to BK virus and SV40. It was discovered in 1971 and named using the two initials of a patient with progressive multifocal leukoencephalopathy...

 which occurs in 70% of the population in latent
Virus latency
Virus latency is the ability of a pathogenic virus to lie dormant within a cell, denoted as the lysogenic part of the viral life cycle. A latent viral infection is a type of persistent viral infection which is distinguished from a chronic viral infection...

 form, causing disease only when the immune system has been severely weakened, as is the case for AIDS patients. It progresses rapidly, usually causing death within months of diagnosis.

AIDS dementia complex
AIDS dementia complex
AIDS dementia complex is a common neurological disorder associated with HIV infection and AIDS. It is a metabolic encephalopathy induced by HIV infection and fueled by immune activation of brain macrophages and microglia...

 (ADC) is a metabolic encephalopathy
Encephalopathy
Encephalopathy means disorder or disease of the brain. In modern usage, encephalopathy does not refer to a single disease, but rather to a syndrome of global brain dysfunction; this syndrome can be caused by many different illnesses.-Terminology:...

 induced by HIV infection and fueled by immune activation of HIV infected brain macrophage
Macrophage
Macrophages are cells produced by the differentiation of monocytes in tissues. Human macrophages are about in diameter. Monocytes and macrophages are phagocytes. Macrophages function in both non-specific defense as well as help initiate specific defense mechanisms of vertebrate animals...

s and microglia
Microglia
Microglia are a type of glial cell that are the resident macrophages of the brain and spinal cord, and thus act as the first and main form of active immune defense in the central nervous system . Microglia constitute 20% of the total glial cell population within the brain...

. These cells are productively infected by HIV and secrete neurotoxin
Neurotoxin
A neurotoxin is a toxin that acts specifically on nerve cells , usually by interacting with membrane proteins such as ion channels. Some sources are more general, and define the effect of neurotoxins as occurring at nerve tissue...

s of both host and viral origin. Specific neurological impairments are manifested by cognitive, behavioral, and motor abnormalities that occur after years of HIV infection and are 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 sometimes seen in patients with advanced HIV illness; it presents with more irritability and cognitive impairment and less euphoria than a manic episode
Mania
Mania, the presence of which is a criterion for certain psychiatric diagnoses, is a state of abnormally elevated or irritable mood, arousal, and/ or energy levels. In a sense, it is the opposite of depression...

 associated with true bipolar disorder
Bipolar disorder
Bipolar disorder or bipolar affective disorder, historically known as manic–depressive disorder, is a psychiatric diagnosis that describes a category of mood disorders defined by the presence of one or more episodes of abnormally elevated energy levels, cognition, and mood with or without one or...

. Unlike the latter condition, it may have a more chronic course. This syndrome is less often seen with the advent of multi-drug therapy.

Tumors


Patients with HIV infection have substantially increased incidence of several cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...

s. This is primarily due to co-infection with an oncogenic
Oncogene
An oncogene is a gene that has the potential to cause cancer. In tumor cells, they are often mutated or expressed at high levels.An oncogene is a gene found in the chromosomes of tumor cells whose activation is associated with the initial and continuing conversion of normal cells into cancer...

 DNA virus
DNA virus
A DNA virus is a virus that has DNA as its genetic material and replicates using a DNA-dependent DNA polymerase. The nucleic acid is usually double-stranded DNA but may also be single-stranded DNA . DNA viruses belong to either Group I or Group II of the Baltimore classification system for viruses...

, especially Epstein-Barr virus
Epstein-Barr virus
The Epstein–Barr virus , also called human herpesvirus 4 , is a virus of the herpes family and is one of the most common viruses in humans. It is best known as the cause of infectious mononucleosis...

 (EBV), Kaposi's sarcoma-associated herpesvirus
Kaposi's sarcoma-associated herpesvirus
Kaposi's sarcoma-associated herpesvirus is one of seven currently known human cancer viruses, or oncoviruses. It is also the eighth human herpesvirus; its formal name according to the International Committee on Taxonomy of Viruses is HHV-8. Like other herpesviruses, its informal name is used...

 (KSHV) (also known as human herpesvirus-8 [HHV-8]), and human papillomavirus
Papillomaviridae
Papillomaviridae is an ancient taxonomic family of non-enveloped DNA viruses, collectively known as papillomaviruses. Several hundred species of papillomaviruses, traditionally referred to as "types", have been identified infecting all carefully inspected birds and mammals, but also a small number...

 (HPV).

Kaposi's sarcoma (KS) is the most common tumor in HIV-infected patients. The appearance of this tumor in young homosexual men in 1981 was one of the first signals of the AIDS epidemic. Caused by a gammaherpes
Gammaherpesvirinae
Gammaherpesvirinae is a subfamily of Herpesviridae distinguished by reproducing at a more variable rate than other subfamilies of Herpesviridae...

 virus called Kaposi's sarcoma-associated herpes virus (KSHV), it often appears as purplish nodules
Nodule (medicine)
For use of the term nodule in dermatology, see Nodule In medicine, a nodule refers to a relatively hard, roughly spherical abnormal structure....

 on the skin, but can affect other organs, especially the mouth
Mouth
The mouth is the first portion of the alimentary canal that receives food andsaliva. The oral mucosa is the mucous membrane epithelium lining the inside of the mouth....

, gastrointestinal tract, and lungs. High-grade B cell
B cell
B cells are lymphocytes that play a large role in the humoral immune response . The principal functions of B cells are to make antibodies against antigens, perform the role of antigen-presenting cells and eventually develop into memory B cells after activation by antigen interaction...

 lymphoma
Lymphoma
Lymphoma is a cancer in the lymphatic cells of the immune system. Typically, lymphomas present as a solid tumor of lymphoid cells. Treatment might involve chemotherapy and in some cases radiotherapy and/or bone marrow transplantation, and can be curable depending on the histology, type, and stage...

s such as Burkitt's lymphoma
Burkitt's lymphoma
Burkitt's lymphoma is a cancer of the lymphatic system...

, Burkitt's-like lymphoma, diffuse large B-cell lymphoma (DLBCL), and primary central nervous system lymphoma
Primary central nervous system lymphoma
A primary central nervous system lymphoma , also known as microglioma and primary brain lymphoma, is a primary intracranial tumor appearing mostly in patients with severe immunosuppression . PCNSLs represent around 20% of all cases of lymphomas in HIV infections...

 present more often in HIV-infected patients. These particular cancers often foreshadow a poor prognosis. Epstein-Barr virus
Epstein-Barr virus
The Epstein–Barr virus , also called human herpesvirus 4 , is a virus of the herpes family and is one of the most common viruses in humans. It is best known as the cause of infectious mononucleosis...

 (EBV) or KSHV cause many of these lymphomas. In HIV-infected patients, lymphoma often arises in extranodal sites such as the gastrointestinal tract. When they occur in an HIV-infected patient, KS and aggressive B cell lymphomas confer a diagnosis of AIDS.

Invasive cervical cancer
Cervical cancer
Cervical cancer is malignant neoplasm of the cervix uteri or cervical area. One of the most common symptoms is abnormal vaginal bleeding, but in some cases there may be no obvious symptoms until the cancer is in its advanced stages...

 in HIV-infected women is also considered AIDS-defining, it is caused by human papillomavirus
Human papillomavirus
Human papillomavirus is a member of the papillomavirus family of viruses that is capable of infecting humans. Like all papillomaviruses, HPVs establish productive infections only in keratinocytes of the skin or mucous membranes...

 (HPV).

In addition to the AIDS-defining tumors listed above, HIV-infected patients are at increased risk of certain other tumors, notably Hodgkin's disease, anal
Anal cancer
Anal cancer is a type of cancer which arises from the anus, the distal orifice of the gastrointestinal tract. It is a distinct entity from the more common colorectal cancer. The etiology, risk factors, clinical progression, staging, and treatment are all different. Anal cancer is typically a...

 and rectal carcinoma
Colorectal cancer
Colorectal cancer, commonly known as bowel cancer, is a cancer caused by uncontrolled cell growth , in the colon, rectum, or vermiform appendix. Colorectal cancer is clinically distinct from anal cancer, which affects the anus....

s, hepatocellular carcinoma
Hepatocellular carcinoma
Hepatocellular carcinoma is the most common type of liver cancer. Most cases of HCC are secondary to either a viral hepatitide infection or cirrhosis .Compared to other cancers, HCC is quite a rare tumor in the United States...

s, head and neck cancer
Head and neck cancer
Head and neck cancer refers to a group of biologically similar cancers that start in the upper aerodigestive tract, including the lip, oral cavity , nasal cavity , paranasal sinuses, pharynx, and larynx. 90% of head and neck cancers are squamous cell carcinomas , originating from the mucosal lining...

s, and lung cancer
Lung cancer
Lung cancer is a disease characterized by uncontrolled cell growth in tissues of the lung. If left untreated, this growth can spread beyond the lung in a process called metastasis into nearby tissue and, eventually, into other parts of the body. Most cancers that start in lung, known as primary...

. Some of these are causes by viruses, such as Hodgkin's disease (EBV), anal/rectal cancers (HPV), head and neck cancers (HPV), and hepatocellular carcinoma (hepatitis B or C
Hepatitis C
Hepatitis C is an infectious disease primarily affecting the liver, caused by the hepatitis C virus . The infection is often asymptomatic, but chronic infection can lead to scarring of the liver and ultimately to cirrhosis, which is generally apparent after many years...

). Other contributing factors include exposure to carcinogens (cigarette smoke for lung cancer), or living for years with subtle immune defects.

Interestingly, the incidence of many common tumors, such as breast cancer
Breast cancer
Breast cancer is cancer originating from breast tissue, most commonly from the inner lining of milk ducts or the lobules that supply the ducts with milk. Cancers originating from ducts are known as ductal carcinomas; those originating from lobules are known as lobular carcinomas...

 or colon cancer
Colorectal cancer
Colorectal cancer, commonly known as bowel cancer, is a cancer caused by uncontrolled cell growth , in the colon, rectum, or vermiform appendix. Colorectal cancer is clinically distinct from anal cancer, which affects the anus....

, does not increase in HIV-infected patients. In areas where HAART
Antiretroviral drug
Antiretroviral drugs are medications for the treatment of infection by retroviruses, primarily HIV. When several such drugs, typically three or four, are taken in combination, the approach is known as Highly Active Antiretroviral Therapy, or HAART...

 is extensively used to treat AIDS, the incidence of many AIDS-related malignancies has decreased, but at the same time malignant cancers overall have become the most common cause of death of HIV-infected patients. In recent years, an increasing proportion of these deaths have been from non-AIDS-defining cancers.

Other infections


AIDS patients often develop opportunistic infections that present with non-specific symptoms, especially low-grade fever
Fever
Fever is a common medical sign characterized by an elevation of temperature above the normal range of due to an increase in the body temperature regulatory set-point. This increase in set-point triggers increased muscle tone and shivering.As a person's temperature increases, there is, in...

s and weight loss. These include opportunistic infection with Mycobacterium avium
Mycobacterium avium-intracellulare infection
Mycobacterium avium-intracellulare is an atypical mycobacterial infection which can occur in the later stages of AIDS. It can also affect people who do not have AIDS and usually first presents as a persistent cough. Additionally, cases in elderly men have increased recently...

-intracellulare and cytomegalovirus
Cytomegalovirus
Cytomegalovirus is a viral genus of the viral group known as Herpesviridae or herpesviruses. It is typically abbreviated as CMV: The species that infects humans is commonly known as human CMV or human herpesvirus-5 , and is the most studied of all cytomegaloviruses...

 (CMV). CMV can cause colitis, as described above, and CMV retinitis
Cytomegalovirus retinitis
Cytomegalovirus retinitis, also known as CMV retinitis, is an inflammation of the eye's retina that can lead to blindness.-Presentation:...

 can cause blindness
Blindness
Blindness is the condition of lacking visual perception due to physiological or neurological factors.Various scales have been developed to describe the extent of vision loss and define blindness...

.

Penicilliosis
Penicilliosis
Penicilliosis is an infection caused by Penicillium marneffei.It is a dimorphic fungus.-Epidemiology:Once considered rare, its occurrence has increased due to AIDS...

 due to Penicillium marneffei
Penicillium marneffei
Penicillium species are usually regarded as unimportant in terms of causing human disease. Penicillium marneffei, discovered in 1956, is different...

 is now the third most common opportunistic infection (after extrapulmonary tuberculosis and cryptococcosis
Cryptococcosis
Cryptococcosis, or cryptococcal disease, is a potentially fatal fungal disease. It is caused by one of two species; Cryptococcus neoformans and Cryptococcus gattii. These were all previously thought to be subspecies of C...

) in HIV-positive individuals within the endemic area of Southeast Asia
Southeast Asia
Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...

.

An infection that often goes unrecognized in AIDS patients is Parvovirus B19
Parvovirus B19
The B19 virus, generally referred to as parvovirus B19 or sometimes erythrovirus B19, was the first known human virus in the family of parvoviruses, genus erythrovirus...

. Its main consequence is anemia, which is difficult to distinguish from the effects of antiretroviral drugs used to treat AIDS itself.

Cause





AIDS is the ultimate clinical consequence of infection
Infection
An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...

 with HIV. HIV is a retrovirus
Retrovirus
A retrovirus is an RNA virus that is duplicated in a host cell using the reverse transcriptase enzyme to produce DNA from its RNA genome. The DNA is then incorporated into the host's genome by an integrase enzyme. The virus thereafter replicates as part of the host cell's DNA...

 that primarily infects vital organs of the human immune system
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...

 such as CD4+ T cells
T helper cell
T helper cells are a sub-group of lymphocytes, a type of white blood cell, that play an important role in the immune system, particularly in the adaptive immune system. These cells have no cytotoxic or phagocytic activity; they cannot kill infected host cells or pathogens. Rather, they help other...

 (a subset of T cell
T cell
T cells or T lymphocytes belong to a group of white blood cells known as lymphocytes, and play a central role in cell-mediated immunity. They can be distinguished from other lymphocytes, such as B cells and natural killer cells , by the presence of a T cell receptor on the cell surface. They are...

s), macrophage
Macrophage
Macrophages are cells produced by the differentiation of monocytes in tissues. Human macrophages are about in diameter. Monocytes and macrophages are phagocytes. Macrophages function in both non-specific defense as well as help initiate specific defense mechanisms of vertebrate animals...

s and dendritic cell
Dendritic cell
Dendritic cells are immune cells forming part of the mammalian immune system. Their main function is to process antigen material and present it on the surface to other cells of the immune system. That is, dendritic cells function as antigen-presenting cells...

s. It directly and indirectly destroys CD4+ T cells.

Once the number of CD4+ T cells per microliter
Litre
pic|200px|right|thumb|One litre is equivalent to this cubeEach side is 10 cm1 litre water = 1 kilogram water The litre is a metric system unit of volume equal to 1 cubic decimetre , to 1,000 cubic centimetres , and to 1/1,000 cubic metre...

 (µL) of blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

 drops below 200, cellular immunity
Cell-mediated immunity
Cell-mediated immunity is an immune response that does not involve antibodies but rather involves the activation of macrophages, natural killer cells , antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen...

 is lost. Acute
Acute (medicine)
In medicine, an acute disease is a disease with either or both of:# a rapid onset, as in acute infection# a short course ....

 HIV infection usually progresses over time to clinical latent HIV infection and then to early symptom
Symptom
A symptom is a departure from normal function or feeling which is noticed by a patient, indicating the presence of disease or abnormality...

atic HIV infection and later to AIDS, which is identified either on the basis of the amount of CD4+ T cells remaining in the blood, and/or the presence of certain infections, as noted above.

In the absence of antiretroviral therapy
Antiretroviral drug
Antiretroviral drugs are medications for the treatment of infection by retroviruses, primarily HIV. When several such drugs, typically three or four, are taken in combination, the approach is known as Highly Active Antiretroviral Therapy, or HAART...

, the median
Median
In probability theory and statistics, a median is described as the numerical value separating the higher half of a sample, a population, or a probability distribution, from the lower half. The median of a finite list of numbers can be found by arranging all the observations from lowest value to...

 time of progression from HIV infection to AIDS
HIV Disease Progression Rates
Following infection with HIV-1, the rate of clinical disease progression varies between individuals. Factors such as host susceptibility, genetics and immune function, health care and co-infections as well as viral genetic variability may affect the rate of progression to AIDS.-Rapid progressors:A...

 is nine to ten years, and the median survival time after developing AIDS is only 9.2 months. However, the rate of clinical disease 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's ability 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 disease progression than younger people.

Poor access to health care
Health care
Health care is the diagnosis, treatment, and prevention of disease, illness, injury, and other physical and mental impairments in humans. Health care is delivered by practitioners in medicine, chiropractic, dentistry, nursing, pharmacy, allied health, and other care providers...

 and the existence of coexisting infections such as tuberculosis
Tuberculosis
Tuberculosis, MTB, or TB is a common, and in many cases lethal, infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis. Tuberculosis usually attacks the lungs but can also affect other parts of the body...

 also may predispose people to faster disease progression. The infected person's genetic inheritance
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....

 plays an important role and some people are resistant
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...

 to certain strains of HIV. An example of this is people with the homozygous
Zygosity
Zygosity refers to the similarity of alleles for a trait in an organism. If both alleles are the same, the organism is homozygous for the trait. If both alleles are different, the organism is heterozygous for that trait...

 CCR5-Δ32
CCR5
C-C chemokine receptor type 5, also known as CCR5, is a protein that in humans is encoded by the CCR5 gene. CCR5 is a member of the beta chemokine receptors family of integral membrane proteins...

 variation are resistant to infection with certain strains
Strain (biology)
In biology, a strain is a low-level taxonomic rank used in three related ways.-Microbiology and virology:A strain is a genetic variant or subtype of a micro-organism . For example, a "flu strain" is a certain biological form of the influenza or "flu" virus...

 of HIV. HIV is genetically variable and exists as different strains, which cause different rates of 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 sexual intercourse with a virgin will cure AIDS, and that HIV can infect only homosexual men and drug users. Other misconceptions are that any act of anal intercourse between gay men can lead to AIDS infection, and that open discussion of homosexuality and HIV in schools will lead to increased rates of homosexuality and AIDS.

Sexual transmission


Sexual transmission occurs with the contact between sexual secretions of one person with the rectal, genital or oral mucous membrane
Mucous membrane
The mucous membranes are linings of mostly endodermal origin, covered in epithelium, which are involved in absorption and secretion. They line cavities that are exposed to the external environment and internal organs...

s of another. Unprotected sexual acts are riskier for the receptive partner
Sexual intercourse
Sexual intercourse, also known as copulation or coitus, commonly refers to the act in which a male's penis enters a female's vagina for the purposes of sexual pleasure or reproduction. The entities may be of opposite sexes, or they may be hermaphroditic, as is the case with snails...

 than for the insertive partner
Sexual penetration
Sexual penetration is a sexual activity that involves the entry into a bodily orifice, such as the vagina, anus or mouth, with a body part or an object....

, and the risk for transmitting HIV through unprotected anal intercourse is greater than the risk from vaginal intercourse or oral sex.

However, oral sex is not entirely safe, as HIV can be transmitted through both insertive and receptive oral sex. Sexual assault
Sexual assault
Sexual assault is an assault of a sexual nature on another person, or any sexual act committed without consent. Although sexual assaults most frequently are by a man on a woman, it may involve any combination of two or more men, women and children....

 greatly increases the risk of HIV transmission as condoms are rarely employed and physical trauma to 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
Perry N. Halkitis
Perry N. Halkitis is an American psychologist known for his research on issues of health, human behavior, and developmental psychology, with a specific application to the domains of HIV/AIDS, substance abuse, and mental health burden....

 found that methamphetamine usage does significantly relate to unprotected sexual behavior. The study found methamphetamine users to be at a higher risk for contracting HIV.

Other sexually transmitted infection
Sexually transmitted disease
Sexually transmitted disease , also known as a sexually transmitted infection or venereal disease , is an illness that has a significant probability of transmission between humans by means of human sexual behavior, including vaginal intercourse, oral sex, and anal sex...

s (STI) increase the risk of HIV transmission and infection, because they cause the disruption of the normal epithelial
Epithelium
Epithelium is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. Epithelial tissues line the cavities and surfaces of structures throughout the body, and also form many glands. Functions of epithelial cells include secretion, selective...

 barrier by genital ulcer
Genital ulcer
A Genital ulcer is an ulcer located on the genital area, usually caused by a sexually transmitted disease such as genital herpes, syphilis, chancroid, or thrush. Some other signs of having genital ulcers include enlarged lymph nodes in the groin area, or vesicular lesions, which are small, elevated...

ation and/or microulceration; and by accumulation of pools of HIV-susceptible or HIV-infected cells (lymphocyte
Lymphocyte
A lymphocyte is a type of white blood cell in the vertebrate immune system.Under the microscope, lymphocytes can be divided into large lymphocytes and small lymphocytes. Large granular lymphocytes include natural killer cells...

s and macrophage
Macrophage
Macrophages are cells produced by the differentiation of monocytes in tissues. Human macrophages are about in diameter. Monocytes and macrophages are phagocytes. Macrophages function in both non-specific defense as well as help initiate specific defense mechanisms of vertebrate animals...

s) in semen and vaginal secretions. Epidemiological studies from sub-Saharan Africa, Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

 and North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

 suggest that genital ulcers, such as those caused by syphilis
Syphilis
Syphilis is a sexually transmitted infection caused by the spirochete bacterium Treponema pallidum subspecies pallidum. The primary route of transmission is through sexual contact; however, it may also be transmitted from mother to fetus during pregnancy or at birth, resulting in congenital syphilis...

 and/or chancroid
Chancroid
Chancroid is a sexually transmitted infection characterized by painful sores on the genitalia...

, increase the risk of becoming infected with HIV by about fourfold. There is also a significant although lesser increase in risk from STIs such as gonorrhea
Gonorrhea
Gonorrhea is a common sexually transmitted infection caused by the bacterium Neisseria gonorrhoeae. The usual symptoms in men are burning with urination and penile discharge. Women, on the other hand, are asymptomatic half the time or have vaginal discharge and pelvic pain...

, chlamydia and trichomoniasis
Trichomoniasis
Trichomoniasis, sometimes referred to as "trich", is a common cause of vaginitis. It is a sexually transmitted disease, and is caused by the single-celled protozoan parasite Trichomonas vaginalis producing mechanical stress on host cells and then ingesting cell fragments after cell death...

, which all cause local accumulations of lymphocytes and macrophages.

Transmission of HIV depends on the infectiousness of the index case and the susceptibility of the uninfected partner. Infectivity seems to vary during the course of illness and is not constant between individuals. An undetectable plasma viral load
Viral load
Viral load is a measure of the severity of a viral infection, and can be calculated by estimating the amount of virus in an involved body fluid. For example, it can be given in RNA copies per milliliter of blood plasma...

 does not necessarily indicate a low viral load in the seminal liquid or genital secretions.

However, each 10-fold increase in the level of HIV in the blood is associated with an 81% increased rate of HIV transmission. Women are more susceptible to HIV-1 infection due to hormonal changes, vaginal microbial ecology and 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 their lives by other, more virulent
Virulence
Virulence is by MeSH definition the degree of pathogenicity within a group or species of parasites as indicated by case fatality rates and/or the ability of the organism to invade the tissues of the host. The pathogenicity of an organism - its ability to cause disease - is determined by its...

 strains.

Infection is unlikely in a single encounter. High rates of infection have been linked to a pattern of overlapping long-term sexual relationships. This allows the virus to quickly spread to multiple partners who in turn infect their partners. A pattern of serial monogamy or occasional casual encounters is associated with lower rates of infection.

HIV spreads readily through heterosexual sex in Africa, but less so elsewhere. One possibility being researched is that schistosomiasis
Schistosomiasis
Schistosomiasis is a parasitic disease caused by several species of trematodes , a parasitic worm of the genus Schistosoma. Snails often act as an intermediary agent for the infectious diseases until a new human host is found...

, which affects up to 50% of women in parts of Africa, damages the lining of the vagina.

Blood products



This transmission route is particularly relevant to intravenous drug users, hemophiliacs
Haemophilia
Haemophilia is a group of hereditary genetic disorders that impair the body's ability to control blood clotting or coagulation, which is used to stop bleeding when a blood vessel is broken. Haemophilia A is the most common form of the disorder, present in about 1 in 5,000–10,000 male births...

 and recipients of blood transfusion
Blood transfusion
Blood transfusion is the process of receiving blood products into one's circulation intravenously. Transfusions are used in a variety of medical conditions to replace lost components of the blood...

s and blood products. Sharing and reusing syringe
Syringe
A syringe is a simple pump consisting of a plunger that fits tightly in a tube. The plunger can be pulled and pushed along inside a cylindrical tube , allowing the syringe to take in and expel a liquid or gas through an orifice at the open end of the tube...

s contaminated with HIV-infected blood represents a major risk for infection with HIV.

Needle sharing is the cause of one third of all new HIV-infections in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

, China, and Eastern Europe
Eastern Europe
Eastern Europe is the eastern part of Europe. The term has widely disparate geopolitical, geographical, cultural and socioeconomic readings, which makes it highly context-dependent and even volatile, and there are "almost as many definitions of Eastern Europe as there are scholars of the region"...

. The risk of being infected with HIV from a single prick with a needle that has been used on an HIV-infected person is thought to be about 1 in 150 (see table above). Post-exposure prophylaxis
Post-exposure prophylaxis
Post-exposure prophylaxis is any prophylactic treatment started immediately after exposure to a pathogen , in order to prevent infection by the pathogen and the development of disease.-Rabies:...

 with anti-HIV drugs can further reduce this risk.

This route can also affect people who give and receive tattoo
Tattoo
A tattoo is made by inserting indelible ink into the dermis layer of the skin to change the pigment. Tattoos on humans are a type of body modification, and tattoos on other animals are most commonly used for identification purposes...

s and piercings
Body piercing
Body piercing, a form of body modification, is the practice of puncturing or cutting a part of the human body, creating an opening in which jewelry may be worn. The word piercing can refer to the act or practice of body piercing, or to an opening in the body created by this act or practice...

. Universal precautions
Universal precautions
Universal precautions refers to the practice, in medicine, of avoiding contact with patients' bodily fluids, by means of the wearing of nonporous articles such as medical gloves, goggles, and face shields. The practice was introduced in 1985–88. In 1987, the practice of universal precautions was...

 are frequently not followed in both sub-Saharan Africa and much of Asia because of both a shortage of supplies and inadequate training.

The WHO
World Health Organization
The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...

 estimates that approximately 2.5% of all HIV infections in sub-Saharan Africa are transmitted through unsafe healthcare injections. Because of this, the United Nations General Assembly
United Nations General Assembly
For two articles dealing with membership in the General Assembly, see:* General Assembly members* General Assembly observersThe United Nations General Assembly is one of the five principal organs of the United Nations and the only one in which all member nations have equal representation...

 has urged the nations of the world to implement precautions to prevent HIV transmission by health workers.

The risk of transmitting HIV to blood transfusion
Blood transfusion
Blood transfusion is the process of receiving blood products into one's circulation intravenously. Transfusions are used in a variety of medical conditions to replace lost components of the blood...

 recipients is extremely low in developed countries where improved donor selection and HIV screening is performed. However, according to the WHO
World Health Organization
The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...

, the overwhelming majority of the world's population does not have access to safe blood and between 5% and 10% of the world's HIV infections come from transfusion of infected blood and blood products.

Perinatal transmission


The transmission of the virus from the mother to the child can occur in utero
In utero
In utero is a Latin term literally meaning "in the womb". In biology, the phrase describes the state of an embryo or fetus. In legal contexts, the phrase is used to refer to unborn children. Under common law, unborn children are still considered to exist for property transfer purposes.-See also:*...

 during the last weeks of pregnancy and at childbirth. In the absence of treatment, the transmission rate 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
Caesarean section
A Caesarean section, is a surgical procedure in which one or more incisions are made through a mother's abdomen and uterus to deliver one or more babies, or, rarely, to remove a dead fetus...

, the rate of transmission is just 1%. The risk of infection is influenced by the viral load of the mother at birth, with the higher the viral load, the higher the risk. Breastfeeding
Breastfeeding
Breastfeeding is the feeding of an infant or young child with breast milk directly from female human breasts rather than from a baby bottle or other container. Babies have a sucking reflex that enables them to suck and swallow milk. It is recommended that mothers breastfeed for six months or...

 also increases the risk of transmission by about 4 %.

Pathophysiology


The pathophysiology of AIDS is complex, as is the case with all syndrome
Syndrome
In medicine and psychology, a syndrome is the association of several clinically recognizable features, signs , symptoms , phenomena or characteristics that often occur together, so that the presence of one or more features alerts the physician to the possible presence of the others...

s. Ultimately, HIV causes AIDS by depleting CD4+ T helper lymphocytes. This weakens the immune system and allows opportunistic infection
Opportunistic infection
An opportunistic infection is an infection caused by pathogens, particularly opportunistic pathogens—those that take advantage of certain situations—such as bacterial, viral, fungal or protozoan infections that usually do not cause disease in a healthy host, one with a healthy immune system...

s. T lymphocytes are essential to the immune response and without them, the body cannot fight infections or kill cancerous cells. The mechanism of CD4+ T cell depletion differs in the acute and chronic phases.

During the acute phase, HIV-induced cell lysis and killing of infected cells by cytotoxic T cell
Cytotoxic T cell
A cytotoxic T cell belongs to a sub-group of T lymphocytes that are capable of inducing the death of infected somatic or tumor cells; they kill cells that are infected with viruses , or are otherwise damaged or...

s accounts for CD4+ T cell depletion, although apoptosis
Apoptosis
Apoptosis is the process of programmed cell death that may occur in multicellular organisms. Biochemical events lead to characteristic cell changes and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, and chromosomal DNA fragmentation...

 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 CD4+ T cell numbers.

Although the symptoms of immune deficiency characteristic of AIDS do not appear for years after a person is infected, the bulk of CD4+ T cell loss occurs during the first weeks of infection, especially in the intestinal mucosa, which harbors the majority of the lymphocytes 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, whereas a small fraction of CD4+ T cells in the bloodstream do so.

HIV seeks out and destroys CCR5 expressing CD4+ cells during acute infection. A vigorous immune response eventually controls the infection and initiates the clinically latent phase. However, CD4+ T cells in mucosal tissues remain depleted throughout the infection, although enough remain to initially ward off life-threatening infections.

Continuous HIV replication results in a state of generalized immune activation persisting throughout the chronic phase. Immune activation, which is reflected by the increased activation state of immune cells and release of proinflammatory cytokine
Cytokine
Cytokines are small cell-signaling protein molecules that are secreted by the glial cells of the nervous system and by numerous cells of the immune system and are a category of signaling molecules used extensively in intercellular communication...

s, results from the activity of several HIV gene products and the immune response to ongoing HIV replication. Another cause is the breakdown of the immune surveillance system of the mucosal barrier caused by the depletion 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 the gut’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 provides fresh targets for HIV infection. However, direct killing by HIV alone cannot account for the observed depletion of CD4+ T cells since only 0.01–0.10% of CD4+ T cells in the blood are infected.

A major cause of CD4+ T cell loss appears to result from their heightened susceptibility to apoptosis when the immune system remains activated. Although new T cells are continuously produced by the thymus
Thymus
The thymus is a specialized organ of the immune system. The thymus produces and "educates" T-lymphocytes , which are critical cells of the adaptive immune system....

 to replace the ones lost, the regenerative capacity of the thymus is slowly destroyed by direct infection of its thymocyte
Thymocyte
Thymocytes are hematopoietic progenitor cells present in the thymus. Thymopoiesis is the process in the thymus by which thymocytes differentiate into mature T lymphocytes. The primary function of thymocytes is the generation of T lymphocytes . The thymus provides an inductive environment, which...

s by HIV. Eventually, the minimal number of CD4+ T cells necessary to maintain a sufficient immune response is lost, leading to AIDS

Cells affected


The virus
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...

, entering through which ever route, acts primarily on the following cells:
  • Lymphoreticular system:
    • CD4+ T-Helper cells
      T helper cell
      T helper cells are a sub-group of lymphocytes, a type of white blood cell, that play an important role in the immune system, particularly in the adaptive immune system. These cells have no cytotoxic or phagocytic activity; they cannot kill infected host cells or pathogens. Rather, they help other...

    • Macrophage
      Macrophage
      Macrophages are cells produced by the differentiation of monocytes in tissues. Human macrophages are about in diameter. Monocytes and macrophages are phagocytes. Macrophages function in both non-specific defense as well as help initiate specific defense mechanisms of vertebrate animals...

      s
    • Monocyte
      Monocyte
      Monocytes are a type of white blood cell and are part of the innate immune system of vertebrates including all mammals , birds, reptiles, and fish. Monocytes play multiple roles in immune function...

      s
    • B-lymphocytes
      B cell
      B cells are lymphocytes that play a large role in the humoral immune response . The principal functions of B cells are to make antibodies against antigens, perform the role of antigen-presenting cells and eventually develop into memory B cells after activation by antigen interaction...

  • Certain endothelial
    Endothelium
    The endothelium is the thin layer of cells that lines the interior surface of blood vessels, forming an interface between circulating blood in the lumen and the rest of the vessel wall. These cells are called endothelial cells. Endothelial cells line the entire circulatory system, from the heart...

     cells
  • Central nervous system
    Central nervous system
    The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...

    :
    • Microglia
      Microglia
      Microglia are a type of glial cell that are the resident macrophages of the brain and spinal cord, and thus act as the first and main form of active immune defense in the central nervous system . Microglia constitute 20% of the total glial cell population within the brain...

       of the nervous system
    • Astrocyte
      Astrocyte
      Astrocytes , also known collectively as astroglia, are characteristic star-shaped glial cells in the brain and spinal cord...

      s
    • Oligodendrocyte
      Oligodendrocyte
      Oligodendrocytes , or oligodendroglia , are a type of brain cell. They are a variety of neuroglia. Their main function is the insulation of axons in the central nervous system of some vertebrates...

      s
    • Neuron
      Neuron
      A neuron is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core components of the nervous...

      es – indirectly by the action of cytokine
      Cytokine
      Cytokines are small cell-signaling protein molecules that are secreted by the glial cells of the nervous system and by numerous cells of the immune system and are a category of signaling molecules used extensively in intercellular communication...

      s and the gp-120

The effect


The virus
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...

 has cytopathic effect
Cytopathic effect
Cytopathic effect or cytopathogenic effect refers to degenerative changes in cells, especially in tissue culture, and may be associated with the multiplication of certain viruses....

s but how it does it is still not quite clear. It can remain inactive in these cells for long periods, though. This effect is hypothesized to be due to the CD4-gp120 interaction.
  • The most prominent effect of HIV is its T-helper cell suppression and lysis. The cell is simply killed off or deranged to the point of being function-less (they do not respond to foreign antigen
    Antigen
    An antigen is a foreign molecule that, when introduced into the body, triggers the production of an antibody by the immune system. The immune system will then kill or neutralize the antigen that is recognized as a foreign and potentially harmful invader. These invaders can be molecules such as...

    s). The infected B-cells can not produce enough antibodies either. Thus the immune system collapses leading to the familiar AIDS complications, like infections and neoplasms (vide supra).
  • Infection of the cells of the CNS cause acute aseptic meningitis
    Aseptic meningitis
    Aseptic meningitis, or sterile meningitis, is a condition in which the layers lining the brain, meninges, become inflamed and a pyogenic bacterial source is not to blame. Meningitis is diagnosed on a history of characteristic symptoms and certain examination findings...

    , subacute encephalitis
    Encephalitis
    Encephalitis is an acute inflammation of the brain. Encephalitis with meningitis is known as meningoencephalitis. Symptoms include headache, fever, confusion, drowsiness, and fatigue...

    , vacuolar myelopathy and peripheral neuropathy
    Peripheral neuropathy
    Peripheral neuropathy is the term for damage to nerves of the peripheral nervous system, which may be caused either by diseases of or trauma to the nerve or the side-effects of systemic illness....

    . Later it leads to even AIDS dementia complex.
  • The CD4-gp120 interaction (see above) is also permissive to other viruses like Cytomegalovirus
    Cytomegalovirus
    Cytomegalovirus is a viral genus of the viral group known as Herpesviridae or herpesviruses. It is typically abbreviated as CMV: The species that infects humans is commonly known as human CMV or human herpesvirus-5 , and is the most studied of all cytomegaloviruses...

    , Hepatitis virus
    Viral hepatitis
    Viral hepatitis is liver inflammation due to a viral infection. It may present in acute or chronic forms. The most common causes of viral hepatitis are the five unrelated hepatotropic viruses Hepatitis A, Hepatitis B, Hepatitis C, Hepatitis D, and Hepatitis E...

    , Herpes simplex
    Herpes simplex
    Herpes simplex is a viral disease caused by both Herpes simplex virus type 1 and type 2 . Infection with the herpes virus is categorized into one of several distinct disorders based on the site of infection. Oral herpes, the visible symptoms of which are colloquially called cold sores or fever...

     virus, etc. These viruses lead to further cell damage i. e. cytopathy.

Molecular basis


For details, see:
  • Structure and genome of HIV
  • HIV replication cycle
  • HIV tropism
    HIV tropism
    HIV tropism refers to the cell type that the human immunodeficiency virus infects and replicates in. HIV tropism of a patient's virus is measured by the Trofile assay....


Diagnosis


The diagnosis of AIDS in a person infected with HIV is based on the presence of certain signs or symptoms. Since June 5, 1981, many definitions have been developed for epidemiological
Epidemiology
Epidemiology is the study of health-event, health-characteristic, or health-determinant patterns in a population. It is the cornerstone method of public health research, and helps inform policy decisions and evidence-based medicine by identifying risk factors for disease and targets for preventive...

 surveillance such as the Bangui definition
1985 World Health Organization AIDS surveillance case definition
The 1985 World Health Organization AIDS surveillance case definition was developed in October 1985, at a conference of public health officials including representatives of the Centers for Disease Control and World Health Organization in Bangui, Central African Republic. For this reason, it became...

 and the 1994 expanded World Health Organization AIDS case definition
1994 expanded World Health Organization AIDS case definition
The 1994 expanded World Health Organization AIDS case definition came around through the developments in the understanding of the spectrum of severe HIV-related illness both in developed and developing countries, and the increased availability of laboratory diagnostic methods, a meeting was...

. However, clinical staging of patients was not an intended use for these systems as they are neither sensitive, nor specific. In developing countries, the World Health Organization
World Health Organization
The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...

 staging system for HIV infection and disease, using clinical and laboratory data, is used and in developed countries, the Centers for Disease Control
Centers for Disease Control and Prevention
The Centers for Disease Control and Prevention are a United States federal agency under the Department of Health and Human Services headquartered in Druid Hills, unincorporated DeKalb County, Georgia, in Greater Atlanta...

 (CDC) Classification System is used.

WHO disease staging system


In 1990, the World Health Organization
World Health Organization
The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...

 (WHO) grouped these infections and conditions together by introducing a staging system for patients infected with HIV-1. An update took place in September 2005. Most of these conditions are opportunistic infection
Opportunistic infection
An opportunistic infection is an infection caused by pathogens, particularly opportunistic pathogens—those that take advantage of certain situations—such as bacterial, viral, fungal or protozoan infections that usually do not cause disease in a healthy host, one with a healthy immune system...

s that are easily treatable in healthy people.
  • Stage I: HIV infection is asymptomatic
    Asymptomatic
    In medicine, a disease is considered asymptomatic if a patient is a carrier for a disease or infection but experiences no symptoms. A condition might be asymptomatic if it fails to show the noticeable symptoms with which it is usually associated. Asymptomatic infections are also called subclinical...

     and not categorized as AIDS
  • Stage II: includes minor mucocutaneous
    Mucous membrane
    The mucous membranes are linings of mostly endodermal origin, covered in epithelium, which are involved in absorption and secretion. They line cavities that are exposed to the external environment and internal organs...

     manifestations and recurrent upper respiratory tract
    Upper respiratory tract
    The upper respiratory tract or upper airway primarily refers to the parts of the respiratory system lying outside of the thorax or above the sternal angle. Another definition commomly used in medicine is the airway above the glottis or vocal cords...

     infections
  • Stage III: includes unexplained chronic diarrhea
    Diarrhea
    Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...

     for longer than a month, severe bacterial infections and pulmonary
    Lung
    The lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...

     tuberculosis
  • Stage IV: includes toxoplasmosis
    Toxoplasmosis
    Toxoplasmosis is a parasitic disease caused by the protozoan Toxoplasma gondii. The parasite infects most genera of warm-blooded animals, including humans, but the primary host is the felid family. Animals are infected by eating infected meat, by ingestion of feces of a cat that has itself...

     of the brain
    Brain
    The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...

    , candidiasis
    Candidiasis
    Thrush redirects here. For the hoof infection see Thrush .Candidiasis or thrush is a fungal infection of any of the Candida species , of which Candida albicans is the most common...

     of the esophagus
    Esophagus
    The esophagus is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. During swallowing, food passes from the mouth through the pharynx into the esophagus and travels via peristalsis to the stomach...

    , trachea
    Vertebrate trachea
    In tetrapod anatomy the trachea, or windpipe, is a tube that connects the pharynx or larynx to the lungs, allowing the passage of air. It is lined with pseudostratified ciliated columnar epithelium cells with goblet cells that produce mucus...

    , bronchi
    Bronchus
    A bronchus is a passage of airway in the respiratory tract that conducts air into the lungs. The bronchus branches into smaller tubes, which in turn become bronchioles....

     or lung
    Lung
    The lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...

    s and Kaposi's sarcoma
    Kaposi's sarcoma
    Kaposi's sarcoma is a tumor caused by Human herpesvirus 8 , also known as Kaposi's sarcoma-associated herpesvirus . It was originally described by Moritz Kaposi , a Hungarian dermatologist practicing at the University of Vienna in 1872. It became more widely known as one of the AIDS defining...

    ; these diseases are indicators of AIDS.

CDC classification system


There are two main definitions for AIDS, both produced by the Centers for Disease Control and Prevention
Centers for Disease Control and Prevention
The Centers for Disease Control and Prevention are a United States federal agency under the Department of Health and Human Services headquartered in Druid Hills, unincorporated DeKalb County, Georgia, in Greater Atlanta...

 (CDC). The older definition is to referring to AIDS using the diseases that were associated with it, for example, lymphadenopathy
Lymphadenopathy
Lymphadenopathy is a term meaning "disease of the lymph nodes." It is, however, almost synonymously used with "swollen/enlarged lymph nodes". It could be due to infection, auto-immune disease, or malignancy....

, 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 people with a CD4+ T cell count below 200 per µL of blood or 14% of all lymphocyte
Lymphocyte
A lymphocyte is a type of white blood cell in the vertebrate immune system.Under the microscope, lymphocytes can be divided into large lymphocytes and small lymphocytes. Large granular lymphocytes include natural killer cells...

s. The majority of new AIDS cases in developed countries
Developed country
A developed country is a country that has a high level of development according to some criteria. Which criteria, and which countries are classified as being developed, is a contentious issue...

 use either this definition or the pre-1993 CDC definition. The AIDS diagnosis still stands even if, after treatment, the CD4+ T cell count rises to above 200 per µL of blood or other AIDS-defining illnesses are cured.

HIV test


Many people are unaware that they are infected with HIV. Less than 1% of the sexually active urban population in Africa has been tested, and this proportion is even lower in rural populations. Furthermore, only 0.5% of pregnant women attending urban health facilities are counseled, tested or receive their test results. Again, this proportion is even lower in rural health facilities. Therefore, donor blood
Blood donation
A blood donation occurs when a person voluntarily has blood drawn and used for transfusions or made into medications by a process called fractionation....

 and blood products used in medicine and medical research are screened for HIV.

HIV tests are usually performed on venous blood. 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 a patient previously known to be negative is evidence of HIV infection. Individuals whose first specimen indicates evidence of HIV infection will have a repeat test on a second blood sample to confirm the results.

The window period
Window period
In medicine, the window period for a test designed to detect a specific disease is the time between first infection and when the test can reliably detect that infection...

 (the time between initial infection and the development of detectable antibodies against the infection) can vary since it can take 3–6  months to seroconvert
Seroconversion
Seroconversion is the development of detectable specific antibodies to microorganisms in the blood serum as a result of infection or immunization. Serology is used to determine antibody positivity...

 and to test positive. Detection of the virus using polymerase chain reaction (PCR
Polymerase chain reaction
The polymerase chain reaction is a scientific technique in molecular biology to amplify a single or a few copies of a piece of DNA across several orders of magnitude, generating thousands to millions of copies of a particular DNA sequence....

) during the window period is possible, and evidence suggests that an infection may often be detected earlier than when using a fourth generation EIA screening test.

Positive results obtained by PCR are confirmed by antibody tests.
Routinely used HIV tests for infection in neonates
Infant
A newborn or baby is the very young offspring of a human or other mammal. A newborn is an infant who is within hours, days, or up to a few weeks from birth. In medical contexts, newborn or neonate refers to an infant in the first 28 days after birth...

 and infant
Infant
A newborn or baby is the very young offspring of a human or other mammal. A newborn is an infant who is within hours, days, or up to a few weeks from birth. In medical contexts, newborn or neonate refers to an infant in the first 28 days after birth...

s (i. e., patients younger than 2 years), born to HIV-positive mothers, have no value because of the presence of maternal antibody to HIV in the child's blood. HIV infection can only be diagnosed by PCR, testing for HIV pro-viral DNA in the children's lymphocyte
Lymphocyte
A lymphocyte is a type of white blood cell in the vertebrate immune system.Under the microscope, lymphocytes can be divided into large lymphocytes and small lymphocytes. Large granular lymphocytes include natural killer cells...

s.

Prevention

Estimated per act risk for acquisition
of HIV by exposure route (US only)
Exposure Route Estimated infections
per 10,000 exposures
to an infected source
Blood Transfusion 9,000
Childbirth (to child) 2,500
Needle-sharing injection drug use 67
Percutaneous needle stick 30
Receptive anal intercourse* 50
Insertive anal intercourse* 6.5
Receptive penile-vaginal intercourse* 10
Insertive penile-vaginal intercourse* 5
Receptive oral intercourse 1
Insertive oral intercourse 0.5
* assuming no condom use
§ source refers to oral intercourse
performed on a man


The three main transmission routes of HIV are sexual contact, exposure to infected body fluids or tissues, and from mother to fetus
Fetus
A fetus is a developing mammal or other viviparous vertebrate after the embryonic stage and before birth.In humans, the fetal stage of prenatal development starts at the beginning of the 11th week in gestational age, which is the 9th week after fertilization.-Etymology and spelling variations:The...

 or child during the perinatal period. It is possible to find HIV in the saliva
Saliva
Saliva , referred to in various contexts as spit, spittle, drivel, drool, or slobber, is the watery substance produced in the mouths of humans and most other animals. Saliva is a component of oral fluid. In mammals, saliva is produced in and secreted from the three pairs of major salivary glands,...

, tears
Tears
Tears are secretions that clean and lubricate the eyes. Lacrimation or lachrymation is the production or shedding of tears....

, and urine
Urine
Urine is a typically sterile liquid by-product of the body that is secreted by the kidneys through a process called urination and excreted through the urethra. Cellular metabolism generates numerous by-products, many rich in nitrogen, that require elimination from the bloodstream...

 of 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 significantly reduces their ability to transmit HIV to others, by reducing the amount of virus in their bodily fluids to undetectable levels.

Sexual contact


The majority of HIV infections are acquired through unprotected sexual relations between partners, one of whom has HIV. The primary mode of HIV infection worldwide is through sexual contact between members of the opposite sex.

During a sexual act, only male or female condom
Condom
A condom is a barrier device most commonly used during sexual intercourse to reduce the probability of pregnancy and spreading sexually transmitted diseases . It is put on a man's erect penis and physically blocks ejaculated semen from entering the body of a sexual partner...

s can reduce the risk of infection with HIV and other STDs. The best evidence to date indicates that typical condom use reduces the risk of heterosexual
Heterosexuality
Heterosexuality is romantic or sexual attraction or behavior between members of the opposite sex or gender. As a sexual orientation, heterosexuality refers to "an enduring pattern of or disposition to experience sexual, affectional, physical or romantic attractions to persons of the opposite sex";...

 HIV transmission by approximately 80% over the long-term, though the benefit is likely to be higher if condoms are used correctly on every occasion.

The male latex
Latex
Latex is the stable dispersion of polymer microparticles in an aqueous medium. Latexes may be natural or synthetic.Latex as found in nature is a milky fluid found in 10% of all flowering plants . It is a complex emulsion consisting of proteins, alkaloids, starches, sugars, oils, tannins, resins,...

 condom, if used correctly without oil-based lubricants, is the single most effective available technology to reduce the sexual transmission of HIV and other sexually transmitted infections. Manufacturers recommend that oil-based lubricants such as petroleum jelly
Petroleum jelly
Petroleum jelly, petrolatum, white petrolatum or soft paraffin, CAS number 8009-03-8, is a semi-solid mixture of hydrocarbons , originally promoted as a topical ointment for its healing properties...

, butter, and lard
Lard
Lard is pig fat in both its rendered and unrendered forms. Lard was commonly used in many cuisines as a cooking fat or shortening, or as a spread similar to butter. Its use in contemporary cuisine has diminished because of health concerns posed by its saturated-fat content and its often negative...

 not be used with latex condoms, because they dissolve the latex
Latex
Latex is the stable dispersion of polymer microparticles in an aqueous medium. Latexes may be natural or synthetic.Latex as found in nature is a milky fluid found in 10% of all flowering plants . It is a complex emulsion consisting of proteins, alkaloids, starches, sugars, oils, tannins, resins,...

, making the condoms porous
Porosity
Porosity or void fraction is a measure of the void spaces in a material, and is a fraction of the volume of voids over the total volume, between 0–1, or as a percentage between 0–100%...

. If lubrication is desired, manufacturers recommend using water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

-based lubricants. Oil-based lubricants can be used with polyurethane
Polyurethane
A polyurethane is any polymer composed of a chain of organic units joined by carbamate links. Polyurethane polymers are formed through step-growth polymerization, by reacting a monomer with another monomer in the presence of a catalyst.Polyurethanes are...

 condoms.

Female condom
Female condom
A female condom is a device that is used during sexual intercourse as a barrier contraceptive and to reduce the risk of sexually transmitted infections and unintended pregnancy...

s are commonly made from polyurethane
Polyurethane
A polyurethane is any polymer composed of a chain of organic units joined by carbamate links. Polyurethane polymers are formed through step-growth polymerization, by reacting a monomer with another monomer in the presence of a catalyst.Polyurethanes are...

, but are also made from nitrile
Nitrile
A nitrile is any organic compound that has a -C≡N functional group. The prefix cyano- is used interchangeably with the term nitrile in industrial literature. Nitriles are found in many useful compounds, one example being super glue .Inorganic compounds containing the -C≡N group are not called...

 and latex. They are larger than male condoms and have a stiffened ring-shaped opening with an inner ring designed to be inserted into the vagina keeping 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 studies which suggest that overall protected sexual acts increase relative to unprotected sexual acts where female condoms are available. At present, availability of female condoms is very low and the price remains prohibitive for many women.

Studies on couples where one partner is infected show that with consistent condom use, HIV infection rates for the uninfected partner are below 1% per year. Prevention strategies are well known in developed countries, but epidemiological and behavioral studies in Europe and North America suggest that a substantial minority of young people continue to engage in high-risk practices despite HIV/AIDS knowledge, underestimating their own risk of becoming infected with HIV.

Randomized controlled trial
Randomized controlled trial
A randomized controlled trial is a type of scientific experiment - a form of clinical trial - most commonly used in testing the safety and efficacy or effectiveness of healthcare services or health technologies A randomized controlled trial (RCT) is a type of scientific experiment - a form of...

s have shown that male circumcision
Circumcision
Male circumcision is the surgical removal of some or all of the foreskin from the penis. The word "circumcision" comes from Latin and ....

 lowers the risk of HIV infection among heterosexual men by up to 60%. It is expected that this procedure will be actively promoted in many of the countries affected by HIV, although doing so will involve confronting a number of practical, cultural and attitudinal issues. However, programs to encourage condom use, including providing them free to those in poverty, are estimated to be 95 times more cost effective than circumcision at reducing the rate of HIV in sub-Saharan Africa.

Some experts fear that a lower perception of vulnerability among circumcised men may result in more sexual risk-taking behavior, thus negating its preventive effects. However, one randomized controlled trial indicated that 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 vaginal gel
Microbicides for sexually transmitted diseases
Microbicides for sexually transmitted diseases, are pharmacologic agents and chemical substances that are capable of killing or destroying certain microorganisms that commonly cause human infection, for example the human immunodeficiency virus....

 could reduce infection rates among women by 50% after one year of use, and by 39% after two and a half years. The results of the study, which was conducted by the Centre for the Aids Programme of Research in South Africa (CAPRISA
CAPRISA
CAPRISA is the name of an AIDS research center based in Durban, South Africa.-History:...

), were published in Science
Science (journal)
Science is the academic journal of the American Association for the Advancement of Science and is one of the world's top scientific journals....

 magazine in July 2010, and were then presented at an international aids conference in Vienna
Vienna
Vienna is the capital and largest city of the Republic of Austria and one of the nine states of Austria. Vienna is Austria's primary city, with a population of about 1.723 million , and is by far the largest city in Austria, as well as its cultural, economic, and political centre...

.

Body fluid exposure


Health care workers can reduce exposure to HIV by employing precautions to reduce the risk of exposure to contaminated blood. These precautions include barriers such as gloves, masks, protective eyeware or shields, and gowns or aprons which prevent exposure of the skin or mucous membranes to blood borne pathogens. Frequent and thorough washing of the skin immediately after being contaminated with blood or other bodily fluids can reduce the chance of infection. Finally, sharp objects like needles, scalpels and glass, are carefully disposed of to prevent needlestick injuries with contaminated items. Since intravenous drug use is an important factor in HIV transmission in developed countries, harm reduction
Harm reduction
Harm reduction refers to a range of public health policies designed to reduce the harmful consequences associated with recreational drug use and other high risk activities...

 strategies such as needle-exchange programme
Needle-exchange programme
A Needle & syringe programme or syringe-exchange programme is a social policy based on the philosophy of harm reduction where injecting drug users can obtain hypodermic needles and associated injection equipment at little or no cost. Many programmes are called "exchanges" because some require...

s are used in attempts to reduce the infections caused by drug abuse.

Mother-to-child


Current recommendations state that when replacement feeding, as with a wet nurse
Wet nurse
A wet nurse is a woman who is used to breast feed and care for another's child. Wet nurses are used when the mother is unable or chooses not to nurse the child herself. Wet-nursed children may be known as "milk-siblings", and in some cultures the families are linked by a special relationship of...

, is acceptable, feasible, affordable, sustainable and safe, HIV-infected mothers should avoid breast-feeding their infant. However, if this is not the case, exclusive breast-feeding is recommended during the first months of life and discontinued as soon as possible.

Education


One way to change risky behavior is health education. Several studies have shown the positive impact of education and health literacy on cautious sex behavior. Education works only if it leads to higher health literacy and general cognitive ability. This ability is relevant to understand the relationship between own risky behavior and possible outcomes like HIV-transmission. In July 2010, a UNAIDS
Joint United Nations Programme on HIV/AIDS
The Joint United Nations Programme on HIV and AIDS, or UNAIDS, is the main advocate for accelerated, comprehensive and coordinated global action on the HIV epidemic....

 Inter-Agency Task Team (IATT) on Education commissioned 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-education programmes (such as teacher training, access to related services through schools and the community, or parental attitudes to HIV and AIDS education) and more longitudinal studies on the deeper complexities of the relationship between education and HIV.

Management



See also HIV Treatment and Antiretroviral drug
Antiretroviral drug
Antiretroviral drugs are medications for the treatment of infection by retroviruses, primarily HIV. When several such drugs, typically three or four, are taken in combination, the approach is known as Highly Active Antiretroviral Therapy, or HAART...

.


There is currently no publicly available HIV vaccine
HIV vaccine
An HIV vaccine that protects vaccinated individuals from HIV infection is the goal of many HIV research programmes. Currently, there is no effective vaccine against HIV, the virus that causes AIDS...

 or cure for HIV
HIV
Human immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive...

 or AIDS. The only known methods of prevention are based on avoiding exposure to the virus or, failing that, an antiretroviral treatment directly after a highly significant exposure, called post-exposure prophylaxis
Post-exposure prophylaxis
Post-exposure prophylaxis is any prophylactic treatment started immediately after exposure to a pathogen , in order to prevent infection by the pathogen and the development of disease.-Rabies:...

 (PEP). PEP has a very demanding four week schedule of dosage. It also has very unpleasant side effects including diarrhea
Diarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...

, malaise
Malaise
Malaise is a feeling of general discomfort or uneasiness, of being "out of sorts", often the first indication of an infection or other disease. Malaise is often defined in medicinal research as a "general feeling of being unwell"...

, nausea
Nausea
Nausea , is a sensation of unease and discomfort in the upper stomach with an involuntary urge to vomit. It often, but not always, precedes vomiting...

 and fatigue
Fatigue (physical)
Fatigue is a state of awareness describing a range of afflictions, usually associated with physical and/or mental weakness, though varying from a general state of lethargy to a specific work-induced burning sensation within one's muscles...

.

Antiviral therapy


Current treatment for HIV infection consists of highly active antiretroviral therapy
Antiretroviral drug
Antiretroviral drugs are medications for the treatment of infection by retroviruses, primarily HIV. When several such drugs, typically three or four, are taken in combination, the approach is known as Highly Active Antiretroviral Therapy, or HAART...

, or HAART. This has been highly beneficial to many HIV-infected individuals since its introduction in 1996 when the protease inhibitor-based HAART initially became available. Current optimal HAART options consist of combinations (or "cocktails") consisting of at least three drugs belonging to at least two types, or "classes, " of antiretroviral
Antiretroviral drug
Antiretroviral drugs are medications for the treatment of infection by retroviruses, primarily HIV. When several such drugs, typically three or four, are taken in combination, the approach is known as Highly Active Antiretroviral Therapy, or HAART...

 agents.

Typical regimens consist of two nucleoside analogue reverse transcriptase inhibitors (NARTIs or NRTIs) plus either a protease inhibitor
Protease inhibitor (pharmacology)
Protease inhibitors are a class of drugs used to treat or prevent infection by viruses, including HIV and Hepatitis C. PIs prevent viral replication by inhibiting the activity of proteases, e.g.HIV-1 protease, enzymes used by the viruses to cleave nascent proteins for final assembly of new...

 or a non-nucleoside reverse transcriptase inhibitor (NNRTI). Because HIV disease progression in children is more rapid than in adults, and laboratory parameters are less predictive of risk for disease progression, particularly for young infants, treatment recommendations are more aggressive for children than for adults. In developed countries where HAART is available, doctors assess the viral load
Viral load
Viral load is a measure of the severity of a viral infection, and can be calculated by estimating the amount of virus in an involved body fluid. For example, it can be given in RNA copies per milliliter of blood plasma...

, CD4 counts, rapidity of CD4 decline and patient readiness while deciding when to recommend initiating treatment. Traditionally, treatment has been recommended for otherwise asymptomatic patients when CD4 cell counts fall to 200–250 cells per microliter of blood. However, beginning treatment 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, reduction in complications, and reduction of HIV viremia below the limit of detection, but it does not cure the patient of HIV nor does it prevent the return, once treatment is stopped, of high blood levels of HIV, often HAART resistant. Moreover, it would take more than the lifetime of an individual to be cleared of HIV infection using HAART.

Despite this, many HIV-infected individuals have experienced remarkable improvements in their general health and quality of life, which has led to the plummeting of HIV-associated morbidity and mortality. In the absence of HAART, progression from HIV infection to AIDS occurs at a median
Median
In probability theory and statistics, a median is described as the numerical value separating the higher half of a sample, a population, or a probability distribution, from the lower half. The median of a finite list of numbers can be found by arranging all the observations from lowest value to...

 of between nine to ten years and the median survival time after developing AIDS is only 9.2  months. HAART is thought to increase survival time by between 4 and 12  years.

For some patients, which can be more than fifty percent of patients, HAART achieves far less than optimal results, due to medication intolerance/side effects, prior ineffective antiretroviral therapy and infection with a drug-resistant strain of HIV. Non-adherence and non-persistence with therapy are the major reasons why some people do not benefit from HAART. The reasons for non-adherence and non-persistence are varied. Major psychosocial issues include poor access to medical care, inadequate social supports, psychiatric disease and drug abuse. HAART regimens can also be complex and thus hard to follow, with large numbers of pills taken frequently.

Side effects can also deter people from persisting with HAART, these include lipodystrophy
Lipodystrophy
Lipodystrophy is a medical condition characterized by abnormal or degenerative conditions of the body's adipose tissue. A more specific term, lipoatrophy is used when describing the loss of fat from one area...

, dyslipidaemia
Dyslipidemia
Dyslipidemia or dyslipidaemia is an abnormal amount of lipids in the blood. In developed countries, most dyslipidemias are hyperlipidemias; that is, an elevation of lipids in the blood, often due to diet and lifestyle. The prolonged elevation of insulin levels can lead to dyslipidemia...

, diarrhoea
Diarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...

, insulin resistance
Insulin resistance
Insulin resistance is a physiological condition where the natural hormone insulin becomes less effective at lowering blood sugars. The resulting increase in blood glucose may raise levels outside the normal range and cause adverse health effects, depending on dietary conditions. Certain cell types...

, an increase in cardiovascular
Circulatory system
The circulatory system is an organ system that passes nutrients , gases, hormones, blood cells, etc...

 risks and birth defect
Congenital disorder
A congenital disorder, or congenital disease, is a condition existing at birth and often before birth, or that develops during the first month of life , regardless of causation...

s. Anti-retroviral drugs are expensive, and the majority of the world's infected individuals do not have access to medications and treatments for HIV and AIDS. However, the costs of anti-retroviral drugs have fallen recently in low-income countries. Moreover, patients' quality of life indices benefit from anti-retroviral treatment especially if healthcare services are adequate. In the absence of a cure for AIDS, anti-retroviral treatment is likely to be a cost-effective strategy for enhancing well-being of AIDS patients and their dependents.

Complementary and alternative medicine


In the US, approximately 60% of HIV patients use various forms of complementary or alternative medicine
Alternative medicine
Alternative medicine is any healing practice, "that does not fall within the realm of conventional medicine." It is based on historical or cultural traditions, rather than on scientific evidence....

 (CAM). Despite the widespread use of CAM by people living with HIV/AIDS, the effectiveness of these therapies has not been established. A 2005 Cochrane review of existing high-quality scientific evidence concluded: "There is insufficient evidence to support the use of herbal medicines in HIV-infected individuals and AIDS patients. " Acupuncture
Acupuncture
Acupuncture is a type of alternative medicine that treats patients by insertion and manipulation of solid, generally thin needles in the body....

 has only been proposed for symptomatic relief, but not to treat or cure HIV or AIDS.

Vitamin or mineral supplementation has shown benefit in some studies. Daily doses of selenium
Selenium
Selenium is a chemical element with atomic number 34, chemical symbol Se, and an atomic mass of 78.96. It is a nonmetal, whose properties are intermediate between those of adjacent chalcogen elements sulfur and tellurium...

 can suppress HIV viral burden with an associated improvement of the CD4 count. Selenium can be used as an adjunct therapy to standard antiviral treatments, but cannot itself cure the infection. More evidence is needed before it can be established that selenium supplementation reduces mortality rates. There is some evidence that vitamin A
Vitamin A
Vitamin A is a vitamin that is needed by the retina of the eye in the form of a specific metabolite, the light-absorbing molecule retinal, that is necessary for both low-light and color vision...

 supplementation in children reduces mortality and improves growth. A large Tanzanian trial in immunologically and nutritionally compromised pregnant and lactating women showed a number of benefits to daily multivitamin supplementation for both mothers and children. Dietary intake of micronutrients at RDA
Reference Daily Intake
The Reference Daily Intake or Recommended Daily Intake is the daily intake level of a nutrient that is considered to be sufficient to meet the requirements of 97–98% of healthy individuals in every demographic in the United States .The RDI is used to determine the Daily Value of foods,...

 levels by HIV-infected adults is recommended by the World Health Organization
World Health Organization
The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...

 (WHO). The WHO further states that several studies indicate that supplementation of vitamin A, zinc, and iron can produce adverse effects in HIV positive adults.

Prognosis


Without treatment, the net median survival time after infection with HIV is estimated to be 9 to 11 years, depending on the HIV subtype, and the median survival rate after diagnosis of AIDS in resource-limited settings where treatment is not available ranges between 6 and 19 months, depending on the study. In areas where it is widely available, the development of HAART
Antiretroviral drug
Antiretroviral drugs are medications for the treatment of infection by retroviruses, primarily HIV. When several such drugs, typically three or four, are taken in combination, the approach is known as Highly Active Antiretroviral Therapy, or HAART...

 as effective therapy for HIV infection and AIDS reduced the death rate from this disease by 80%, and raised the life expectancy for a newly diagnosed HIV-infected person to about 20 years.

As new treatments continue to be developed and because HIV continues to evolve
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...

 resistance to treatments, estimates of survival time are likely to continue to change. Without antiretroviral therapy, death normally occurs within a year after the individual progresses to AIDS. Most patients die from opportunistic infections or malignancies
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...

 associated with the progressive failure of the immune system. The rate of clinical disease progression varies widely between individuals and has been shown to be affected by many factors such as host susceptibility and immune function health care 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 experience neurocognitive disorders
AIDS dementia complex
AIDS dementia complex is a common neurological disorder associated with HIV infection and AIDS. It is a metabolic encephalopathy induced by HIV infection and fueled by immune activation of brain macrophages and microglia...

, osteoporosis
Osteoporosis
Osteoporosis is a disease of bones that leads to an increased risk of fracture. In osteoporosis the bone mineral density is reduced, bone microarchitecture is deteriorating, and the amount and variety of proteins in bone is altered...

, neuropathy
Peripheral neuropathy
Peripheral neuropathy is the term for damage to nerves of the peripheral nervous system, which may be caused either by diseases of or trauma to the nerve or the side-effects of systemic illness....

, cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...

s, nephropathy
Nephropathy
Nephropathy refers to damage to or disease of the kidney. An older term for this is nephrosis.-Causes:Causes of nephropathy include administration of analgesics, xanthine oxidase deficiency, and long-term exposure to lead or its salts...

, and cardiovascular disease
Cardiovascular disease
Heart disease or cardiovascular disease are the class of diseases that involve the heart or blood vessels . While the term technically refers to any disease that affects the cardiovascular system , it is usually used to refer to those related to atherosclerosis...

. 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
Tuberculosis
Tuberculosis, MTB, or TB is a common, and in many cases lethal, infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis. Tuberculosis usually attacks the lungs but can also affect other parts of the body...

 co-infection, see AIDS#Pulmonary infections. In Africa, HIV is the single most important factor contributing to the increase in the incidence of TB since 1990.

Epidemiology






The AIDS pandemic can also be seen as several epidemics of separate subtypes; the major factors in its spread are sexual transmission and vertical transmission from mother to child at birth and through breast milk. Despite recent, improved access to antiretroviral treatment and care in many regions of the world, the AIDS pandemic claimed an estimated 2.1  million (range 1.9–2.4  million) lives in 2007 of which an estimated 330,000 were children 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) people were newly infected in 2007, including 420,000 children.

Sub-Saharan Africa remains by far the worst affected region. In 2007 it contained an estimated 68% of all people living with AIDS and 76% of all AIDS deaths, with 1.7  million new infections bringing the number of people living with HIV to 22.5  million, and with 11.4  million AIDS orphans living in the region. Unlike other regions, most people living with HIV in sub-Saharan Africa in 2007 (61%) were women. Adult prevalence
Prevalence
In epidemiology, the prevalence of a health-related state in a statistical population is defined as the total number of cases of the risk factor in the population at a given time, or the total number of cases in the population, divided by the number of individuals in the population...

 in 2007 was an estimated 5.0%, and AIDS continued to be the single largest cause of mortality in this region.

South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

 has the largest population of HIV patients in the world, followed by Nigeria
Nigeria
Nigeria , officially the Federal Republic of Nigeria, is a federal constitutional republic comprising 36 states and its Federal Capital Territory, Abuja. The country is located in West Africa and shares land borders with the Republic of Benin in the west, Chad and Cameroon in the east, and Niger in...

 and India. South & South East Asia are second worst affected; in 2007 this region contained an estimated 18% of all people living with AIDS, and an estimated 300,000 deaths from AIDS. India has an estimated 2.5  million infections and an estimated adult prevalence of 0.36%. Life expectancy
Life expectancy
Life expectancy is the expected number of years of life remaining at a given age. It is denoted by ex, which means the average number of subsequent years of life for someone now aged x, according to a particular mortality experience...

 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
Botswana
Botswana, officially the Republic of Botswana , is a landlocked country located in Southern Africa. The citizens are referred to as "Batswana" . Formerly the British protectorate of Bechuanaland, Botswana adopted its new name after becoming independent within the Commonwealth on 30 September 1966...

.

In the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, young African-American
African American
African Americans are citizens or residents of the United States who have at least partial ancestry from any of the native populations of Sub-Saharan Africa and are the direct descendants of enslaved Africans within the boundaries of the present United States...

 women are also at unusually high risk for HIV infection. African Americans make up 10% of the population but about half of the HIV/AIDS cases nationwide. This is due in part to a lack of information about AIDS and a perception that they are not vulnerable, as well as to limited access to health-care resources and a higher likelihood of sexual contact with at-risk male sexual partners.

There are also geographic disparities in AIDS prevalence in the United States, where it is most common in rural areas and in the southern states, particularly in the Appalachian and Mississippi Delta regions and along the border with Mexico. Approximately 1.1  million persons are living with HIV/AIDS in the United States, and more than 56,000 new infections occur every single year.

History and origin



AIDS was first reported June 5, 1981, when the U. S. Centers for Disease Control (CDC)
Centers for Disease Control and Prevention
The Centers for Disease Control and Prevention are a United States federal agency under the Department of Health and Human Services headquartered in Druid Hills, unincorporated DeKalb County, Georgia, in Greater Atlanta...

 recorded a cluster of Pneumocystis cariniipneumonia (now still classified as PCP but known to be caused by Pneumocystis jirovecii) in five homosexual men in Los Angeles
Los Ángeles
Los Ángeles is the capital of the province of Biobío, in the commune of the same name, in Region VIII , in the center-south of Chile. It is located between the Laja and Biobío rivers. The population is 123,445 inhabitants...

. In the beginning, the CDC did not have an official name for the disease, often referring to it by way of the diseases that were associated with it, for example, lymphadenopathy
Lymphadenopathy
Lymphadenopathy is a term meaning "disease of the lymph nodes." It is, however, almost synonymously used with "swollen/enlarged lymph nodes". It could be due to infection, auto-immune disease, or malignancy....

, the disease after which the discoverers of HIV originally named the virus.
They also used Kaposi's Sarcoma and Opportunistic Infections, the name by which a task force had been set up in 1981.

In the general press, the term GRID, which stood for gay-related immune deficiency
Gay-related immune deficiency
Gay-related immune deficiency was the 1982 name first proposed to describe what is now known as AIDS, after public health scientists noticed clusters of Kaposi's sarcoma and Pneumocystis pneumonia among gay males in Southern California and New York City.During the early history of AIDS, when it was...

, had been coined. The CDC, in search of a name, and looking at the infected communities coined “the 4H disease, ” as it seemed to single out Haiti
Haiti
Haiti , officially the Republic of Haiti , is a Caribbean country. It occupies the western, smaller portion of the island of Hispaniola, in the Greater Antillean archipelago, which it shares with the Dominican Republic. Ayiti was the indigenous Taíno or Amerindian name for the island...

ans, homosexuals
Homosexuality
Homosexuality is romantic or sexual attraction or behavior between members of the same sex or gender. As a sexual orientation, homosexuality refers to "an enduring pattern of or disposition to experience sexual, affectional, or romantic attractions" primarily or exclusively to people of the same...

, hemophilia
Haemophilia
Haemophilia is a group of hereditary genetic disorders that impair the body's ability to control blood clotting or coagulation, which is used to stop bleeding when a blood vessel is broken. Haemophilia A is the most common form of the disorder, present in about 1 in 5,000–10,000 male births...

cs, and heroin users. However, after determining that AIDS was not isolated to the gay community
Gay community
The gay community, or LGBT community, is a loosely defined grouping of LGBT and LGBT-supportive people, organizations and subcultures, united by a common culture and civil rights movements. These communities generally celebrate pride, diversity, individuality, and sexuality...

, the term GRID became misleading and AIDS was introduced 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 identification of the HIV-1 virus comes from the Congo
Democratic Republic of the Congo
The Democratic Republic of the Congo is a state located in Central Africa. It is the second largest country in Africa by area and the eleventh largest in the world...

 in 1959 and 1960 though genetic studies indicate that it passed into the human population from chimpanzee
Chimpanzee
Chimpanzee, sometimes colloquially chimp, is the common name for the two extant species of ape in the genus Pan. The Congo River forms the boundary between the native habitat of the two species:...

s around fifty years earlier. A 2007 study states that a strain of HIV-1 probably moved from Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...

 to Haiti
Haiti
Haiti , officially the Republic of Haiti , is a Caribbean country. It occupies the western, smaller portion of the island of Hispaniola, in the Greater Antillean archipelago, which it shares with the Dominican Republic. Ayiti was the indigenous Taíno or Amerindian name for the island...

 and then entered the United States around 1969.

HIV descends from the related simian immunodeficiency virus
Simian immunodeficiency virus
Simian immunodeficiency virus , also known as African Green Monkey virus and also as Monkey AIDS is a retrovirus able to infect at least 33 species of African primates...

 (SIV), which infects ape
Ape
Apes are Old World anthropoid mammals, more specifically a clade of tailless catarrhine primates, belonging to the biological superfamily Hominoidea. The apes are native to Africa and South-east Asia, although in relatively recent times humans have spread all over the world...

s and monkey
Monkey
A monkey is a primate, either an Old World monkey or a New World monkey. There are about 260 known living species of monkey. Many are arboreal, although there are species that live primarily on the ground, such as baboons. Monkeys are generally considered to be intelligent. Unlike apes, monkeys...

s in Africa. There is evidence that humans who participate in bushmeat
Bushmeat
Bushmeat initially referred to the hunting of wild animals in West and Central Africa and is a calque from the French viande de brousse. Today the term is commonly used for meat of terrestrial wild animals, killed for subsistence or commercial purposes throughout the humid tropics of the Americas,...

 activities, either as hunters or as bushmeat vendors, commonly acquire SIV. However, only a few of these infections were able to cause epidemics in humans, and all did so in the late 19th—early 20th century. To explain why HIV became epidemic only by that time, there are several theories, each invoking specific driving factors that may have promoted SIV adaptation
Adaptation
An adaptation in biology is a trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation....

 to humans, or initial spread: social changes following colonialism
Colonialism
Colonialism is the establishment, maintenance, acquisition and expansion of colonies in one territory by people from another territory. It is a process whereby the metropole claims sovereignty over the colony and the social structure, government, and economics of the colony are changed by...

, rapid transmission of SIV
Simian immunodeficiency virus
Simian immunodeficiency virus , also known as African Green Monkey virus and also as Monkey AIDS is a retrovirus able to infect at least 33 species of African primates...

 through unsafe or unsterile
Asepsis
Asepsis is the state of being free from disease-causing contaminants or, preventing contact with microorganisms. The term asepsis often refers to those practices used to promote or induce asepsis in an operative field in surgery or medicine to prevent infection...

 injections (that is, injections in which the needle is reused without being sterilised), colonial abuses and unsafe smallpox
Smallpox
Smallpox was an infectious disease unique to humans, caused by either of two virus variants, Variola major and Variola minor. The disease is also known by the Latin names Variola or Variola vera, which is a derivative of the Latin varius, meaning "spotted", or varus, meaning "pimple"...

 vaccinations or injections, or prostitution
Prostitution
Prostitution is the act or practice of providing sexual services to another person in return for payment. The person who receives payment for sexual services is called a prostitute and the person who receives such services is known by a multitude of terms, including a "john". Prostitution is one of...

 and the concomitant high frequency of genital ulcer disease
Genital ulcer
A Genital ulcer is an ulcer located on the genital area, usually caused by a sexually transmitted disease such as genital herpes, syphilis, chancroid, or thrush. Some other signs of having genital ulcers include enlarged lymph nodes in the groin area, or vesicular lesions, which are small, elevated...

s (such as syphilis
Syphilis
Syphilis is a sexually transmitted infection caused by the spirochete bacterium Treponema pallidum subspecies pallidum. The primary route of transmission is through sexual contact; however, it may also be transmitted from mother to fetus during pregnancy or at birth, resulting in congenital syphilis...

) in nascent colonial cities. See the main article Origin of AIDS.

One of the first high profile victims of AIDS was the American Rock Hudson
Rock Hudson
Roy Harold Scherer, Jr., later Roy Harold Fitzgerald , known professionally as Rock Hudson, was an American film and television actor, recognized as a romantic leading man during the 1950s and 1960s, most notably in several romantic comedies with Doris Day.Hudson was voted "Star of the Year",...

, a gay actor who had been married and divorced earlier in life, who died on 2 October 1985 having announced that he was suffering from the virus on 25 July that year. It had been diagnosed during 1984. A notable British casualty of AIDS that year was Nicholas Eden
Nicholas Eden, 2nd Earl of Avon
Nicholas Eden, 2nd Earl of Avon , styled Viscount Eden between 1961 and 1977, was a British Conservative politician and younger son of Prime Minister Anthony Eden and his first wife, Beatrice...

, a gay Member of Parliament
Member of Parliament
A Member of Parliament is a representative of the voters to a :parliament. In many countries with bicameral parliaments, the term applies specifically to members of the lower house, as upper houses often have a different title, such as senate, and thus also have different titles for its members,...

 and son of the late prime minister Anthony Eden
Anthony Eden
Robert Anthony Eden, 1st Earl of Avon, KG, MC, PC was a British Conservative politician, who was Prime Minister from 1955 to 1957...

. The virus claimed perhaps its most famous victim yet on 24 November 1991, when British rock star Freddie Mercury
Freddie Mercury
Freddie Mercury was a British musician, singer and songwriter, best known as the lead vocalist of the rock band Queen. As a performer, he was known for his flamboyant stage persona and powerful vocals over a four-octave range...

, lead singer of the band Queen
Queen (band)
Queen are a British rock band formed in London in 1971, originally consisting of Freddie Mercury , Brian May , John Deacon , and Roger Taylor...

, died from an AIDS related illness having only announced that he was suffering from the illness the previous day. However he had been diagnosed as HIV positive during 1987. One of the first high profile heterosexual victims of the virus was Arthur Ashe
Arthur Ashe
Arthur Robert Ashe, Jr. was a professional tennis player, born and raised in Richmond, Virginia. During his career, he won three Grand Slam titles, putting him among the best ever from the United States...

, the American tennis player. He was diagnosed as HIV positive on 31 August 1988, having contracted the virus from blood transfusions during heart surgery earlier in the 1980s. Further tests within 24 hours of the initial diagnosis revealed that Ashe had AIDS, but he did not tell the public about his diagnosis until April 1992. He died, aged 49, as a result of the AIDS virus on 6 February 1993.

A more controversial theory known as the OPV AIDS hypothesis
OPV AIDS hypothesis
The oral polio vaccine AIDS hypothesis argues that the AIDS pandemic originated from live polio vaccines prepared in chimpanzee tissue cultures and then administered to up to one million Africans between 1957 and 1960 in experimental mass vaccination campaigns.Data from molecular biology and...

 suggests that the AIDS epidemic was inadvertently started in the late 1950s in the Belgian Congo
Belgian Congo
The Belgian Congo was the formal title of present-day Democratic Republic of the Congo between King Leopold II's formal relinquishment of his personal control over the state to Belgium on 15 November 1908, and Congolese independence on 30 June 1960.-Congo Free State, 1884–1908:Until the latter...

 by Hilary Koprowski
Hilary Koprowski
Hilary Koprowski is a Polish virologist and immunologist, and inventor of the world's first effective live polio vaccine.-Life:...

's research into a poliomyelitis vaccine
Polio vaccine
Two polio vaccines are used throughout the world to combat poliomyelitis . The first was developed by Jonas Salk and first tested in 1952. Announced to the world by Salk on April 12, 1955, it consists of an injected dose of inactivated poliovirus. An oral vaccine was developed by Albert Sabin...

.

According to scientific consensus
Scientific consensus
Scientific consensus is the collective judgment, position, and opinion of the community of scientists in a particular field of study. Consensus implies general agreement, though not necessarily unanimity. Scientific consensus is not by itself a scientific argument, and it is not part of the...

, this scenario is not supported by the available evidence.

Stigma




AIDS stigma exists around the world in a variety of ways, including ostracism
Shunning
Shunning can be the act of social rejection, or mental rejection. Social rejection is when a person or group deliberately avoids association with, and habitually keeps away from an individual or group. This can be a formal decision by a group, or a less formal group action which will spread to all...

, rejection
Social rejection
Social rejection occurs when an individual is deliberately excluded from a social relationship or social interaction. The topic includes both interpersonal rejection and romantic rejection. A person can be rejected on an individual basis or by an entire group of people...

, discrimination
Discrimination
Discrimination is the prejudicial treatment of an individual based on their membership in a certain group or category. It involves the actual behaviors towards groups such as excluding or restricting members of one group from opportunities that are available to another group. The term began to be...

 and avoidance of HIV infected people; compulsory HIV testing without prior consent
Consent
Consent refers to the provision of approval or agreement, particularly and especially after thoughtful consideration.- Types of consent :*Implied consent is a controversial form of consent which is not expressly granted by a person, but rather inferred from a person's actions and the facts and...

 or protection of confidentiality
Confidentiality
Confidentiality is an ethical principle associated with several professions . In ethics, and in law and alternative forms of legal resolution such as mediation, some types of communication between a person and one of these professionals are "privileged" and may not be discussed or divulged to...

; violence against HIV infected individuals or people who are perceived to be infected with HIV; and the quarantine
Quarantine
Quarantine is compulsory isolation, typically to contain the spread of something considered dangerous, often but not always disease. The word comes from the Italian quarantena, meaning forty-day period....

 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 disease.
  • Courtesy AIDS stigma—stigmatization of people connected to the issue of HIV/AIDS or HIV- positive people.


Often, AIDS stigma is expressed in conjunction with one or more other stigmas, particularly those associated with homosexuality
Homosexuality
Homosexuality is romantic or sexual attraction or behavior between members of the same sex or gender. As a sexual orientation, homosexuality refers to "an enduring pattern of or disposition to experience sexual, affectional, or romantic attractions" primarily or exclusively to people of the same...

, bisexuality
Bisexuality
Bisexuality is sexual behavior or an orientation involving physical or romantic attraction to both males and females, especially with regard to men and women. It is one of the three main classifications of sexual orientation, along with a heterosexual and a homosexual orientation, all a part of the...

, promiscuity
Promiscuity
In humans, promiscuity refers to less discriminating casual sex with many sexual partners. The term carries a moral or religious judgement and is viewed in the context of the mainstream social ideal for sexual activity to take place within exclusive committed relationships...

, prostitution
Prostitution
Prostitution is the act or practice of providing sexual services to another person in return for payment. The person who receives payment for sexual services is called a prostitute and the person who receives such services is known by a multitude of terms, including a "john". Prostitution is one of...

, and intravenous drug use.

In many developed countries
Developed country
A developed country is a country that has a high level of development according to some criteria. Which criteria, and which countries are classified as being developed, is a contentious issue...

, there is an association between AIDS and homosexuality or bisexuality, and this association is correlated with higher levels of sexual prejudice such as anti-homosexual
Homophobia
Homophobia is a term used to refer to a range of negative attitudes and feelings towards lesbian, gay and in some cases bisexual, transgender people and behavior, although these are usually covered under other terms such as biphobia and transphobia. Definitions refer to irrational fear, with the...

 attitudes. There is also a perceived association between AIDS and all male-male sexual behavior, including sex between uninfected men.

Economic impact



HIV and AIDS affects economic growth
Economic growth
In economics, economic growth is defined as the increasing capacity of the economy to satisfy the wants of goods and services of the members of society. Economic growth is enabled by increases in productivity, which lowers the inputs for a given amount of output. Lowered costs increase demand...

 by reducing the availability of human capital
Human capital
Human capitalis the stock of competencies, knowledge and personality attributes embodied in the ability to perform labor so as to produce economic value. It is the attributes gained by a worker through education and experience...

. Without proper nutrition
Nutrition
Nutrition is the provision, to cells and organisms, of the materials necessary to support life. Many common health problems can be prevented or alleviated with a healthy diet....

, health care and medicine that is available in developed countries, large numbers of people suffer and die from AIDS-related complications. They will not only be unable to work, but will also require significant medical care. The forecast is that this will probably cause a collapse of economies and societies in countries with a significant AIDS population. In some heavily infected areas, the epidemic has left behind many orphan
Orphan
An orphan is a child permanently bereaved of or abandoned by his or her parents. In common usage, only a child who has lost both parents is called an orphan...

s cared for by elderly grandparent
Grandparent
Grandparents are the parents of a person's own parent, whether that be a father or a mother. Every sexually-reproducing creature who is not a genetic chimera has a maximum of four genetic grandparents, eight genetic great-grandparents, sixteen genetic great-great-grandparents, etc...

s.

The increased mortality has results in a smaller skilled population
Population decline
Population decline can refer to the decline in population of any organism, but this article refers to population decline in humans. It is a term usually used to describe any great reduction in a human population...

 and labor force
Labor force
In economics, a labor force or labour force is a region's combined civilian workforce, including both the employed and unemployed.Normally, the labor force of a country consists of everyone of working age In economics, a labor force or labour force is a region's combined civilian workforce,...

. This smaller labor force
Labor force
In economics, a labor force or labour force is a region's combined civilian workforce, including both the employed and unemployed.Normally, the labor force of a country consists of everyone of working age In economics, a labor force or labour force is a region's combined civilian workforce,...

 consists of increasingly younger people, with reduced knowledge and work experience
Work experience
Work experience is the experience that a person has been working, or worked in a specific field or occupation.- Volunteer work and internships :...

 leading to reduced productivity. An increase in workers’ time off to look after sick family members or for sick leave
Sick leave
Sick leave is time off from work that workers can use during periods of temporary illness to stay home and address their health and safety needs without losing pay. Some workplaces offer paid sick time as a matter of workplace policy, and in few jurisdictions it is codified into law...

 lowers productivity. Increased mortality reduces the mechanisms that generate human capital and investment
Investment
Investment has different meanings in finance and economics. Finance investment is putting money into something with the expectation of gain, that upon thorough analysis, has a high degree of security for the principal amount, as well as security of return, within an expected period of time...

 in people, through loss of income
Income
Income is the consumption and savings opportunity gained by an entity within a specified time frame, which is generally expressed in monetary terms. However, for households and individuals, "income is the sum of all the wages, salaries, profits, interests payments, rents and other forms of earnings...

 and the death of parents.

By affecting mainly young adults, AIDS reduces the tax
Tax
To tax is to impose a financial charge or other levy upon a taxpayer by a state or the functional equivalent of a state such that failure to pay is punishable by law. Taxes are also imposed by many subnational entities...

able population, in turn reducing the resources available for public expenditure
Government spending
Government spending includes all government consumption, investment but excludes transfer payments made by a state. Government acquisition of goods and services for current use to directly satisfy individual or collective needs of the members of the community is classed as government final...

s such as education and health services not related to AIDS resulting in increasing pressure for the state's finances and slower growth of the economy. This results in a slower growth of the tax base, an effect that is reinforced if 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 in adult mortality shifts the responsibility and blame from the family to the government in caring for these orphans.

On the level of the household, AIDS results in both the loss of income and increased spending on healthcare by the household. The income effects of this lead to spending reduction as well as a substitution effect away from education and towards healthcare and funeral spending. A study in Côte d'Ivoire
Côte d'Ivoire
The Republic of Côte d'Ivoire or Ivory Coast is a country in West Africa. It has an area of , and borders the countries Liberia, Guinea, Mali, Burkina Faso and Ghana; its southern boundary is along the Gulf of Guinea. The country's population was 15,366,672 in 1998 and was estimated to be...

 showed that households with an HIV/AIDS patient spent twice as much on medical expenses as other households.

Religion and AIDS



The topic of religion and AIDS has become highly controversial in the past twenty years, primarily because many prominent religious leaders have publicly declared their opposition to the use of condoms, which scientists feel is currently the only means of stopping the epidemic. However, there is a growing openness to faith-based methods due to the failure rates associated with condoms. Other issues involve religious participation in global health care services and collaboration with secular organizations such as UNAIDS and the World Health Organization.

The religious approach to prevent the spread of AIDS according to a report by American health expert Matthew Hanley titled The Catholic Church and the Global Aids Crisis argues that cultural changes are needed including a re-emphasis on fidelity within marriage and sexual abstinence outside of it.

In addition to prevention, some religious groups have interrupted the treatment of AIDS. According to the African Health Policy Network, some churches in London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...

 claim that prayer will cure AIDS and the Hackney
London Borough of Hackney
The London Borough of Hackney is a London borough of North/North East London, and forms part of inner London. The local authority is Hackney London Borough Council....

-based Centre for the Study of Sexual Health and HIV reports that several people have stopped taking their medication, sometimes on the direct advice of their pastor
Pastor
The word pastor usually refers to an ordained leader of a Christian congregation. When used as an ecclesiastical styling or title, this role may be abbreviated to "Pr." or often "Ps"....

, leading to a number of deaths. The Synagogue Church Of All Nations advertise an "anointing water" to promote God's healing, although the group deny advising people to stop taking medication, and US patent application
Patent application
A patent application is a request pending at a patent office for the grant of a patent for the invention described and claimed by that application. An application consists of a description of the invention , together with official forms and correspondence relating to the application...

 2001051133 similarly suggests that intravenous pure distilled water will eradicate HIV through the mercy of God.

AIDS denialism


A small number of activists question the connection between 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
Scientific community
The scientific community consists of the total body of scientists, its relationships and interactions. It is normally divided into "sub-communities" each working on a particular field within science. Objectivity is expected to be achieved by the scientific method...

, they continue to be promulgated through the Internet
Internet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...

 and have had a significant political impact. In South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

, former President Thabo Mbeki's
Thabo Mbeki
Thabo Mvuyelwa Mbeki is a South African politician who served two terms as the second post-apartheid President of South Africa from 14 June 1999 to 24 September 2008. He is also the brother of Moeletsi Mbeki...

 embrace of AIDS denialism resulted in an ineffective governmental response to the AIDS epidemic that has been blamed for hundreds of thousands of AIDS-related deaths.

AIDS conspiracy theories


Operation INFEKTION
Operation INFEKTION
Operation: INFEKTION was a KGB disinformation campaign to spread information that the United States invented HIV/AIDS as part of a biological weapons research project at Fort Detrick, Maryland. The Soviet Union used it to undermine the United States’ credibility, foster anti-Americanism, isolate...

 was a worldwide Soviet active measures
Active measures
Active Measures were a form of political warfare conducted by the Soviet security services to influence the course of world events, "in addition to collecting intelligence and producing politically correct assessment of it". Active measures ranged "from media manipulations to special actions...

 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.

Research directions



It has been postulated that only a vaccine can halt the pandemic because a vaccine would possibly cost less, thus being affordable for developing countries, and would not require daily treatments. However, even after almost 30  years of research, HIV-1 remains a difficult target for a vaccine.

Research to improve current treatments includes decreasing side effects of current drugs, further simplifying drug regimens to improve adherence, and determining the best sequence of regimens to manage drug resistance. A number of studies have shown that measures to prevent opportunistic infections can be beneficial when treating patients with HIV infection or AIDS. Vaccination
Vaccination
Vaccination is the administration of antigenic material to stimulate the immune system of an individual to develop adaptive immunity to a disease. Vaccines can prevent or ameliorate the effects of infection by many pathogens...

 against hepatitis
Hepatitis
Hepatitis is a medical condition defined by the inflammation of the liver and characterized by the presence of inflammatory cells in the tissue of the organ. The name is from the Greek hepar , the root being hepat- , meaning liver, and suffix -itis, meaning "inflammation"...

 A and B is advised for patients who are not infected with these viruses and are at risk of becoming infected. Patients with substantial immunosuppression are also advised to receive prophylactic therapy for Pneumocystis jiroveci pneumonia
Pneumocystis pneumonia
Pneumocystis pneumonia or pneumocystosis is a form of pneumonia, caused by the yeast-like fungus Pneumocystis jirovecii...

 (PCP), and many patients may benefit from prophylactic therapy for toxoplasmosis
Toxoplasmosis
Toxoplasmosis is a parasitic disease caused by the protozoan Toxoplasma gondii. The parasite infects most genera of warm-blooded animals, including humans, but the primary host is the felid family. Animals are infected by eating infected meat, by ingestion of feces of a cat that has itself...

 and Cryptococcus
Cryptococcus
Cryptococcus is a genus of fungus. Species grow in culture as yeasts. The perfect forms or teleomorphs of Cryptococcus species are filamentous fungi in the genus Filobasidiella...

 meningitis
Meningitis
Meningitis is inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The inflammation may be caused by infection with viruses, bacteria, or other microorganisms, and less commonly by certain drugs...

 as well.

Researchers have discovered an abzyme
Abzyme
An abzyme , also called catmab , is a monoclonal antibody with catalytic activity. Molecules which are modified to gain new catalytic activity are called synzymes...

 that can destroy the protein gp120
Gp120
Envelope glycoprotein GP120 is a glycoprotein exposed on the surface of the HIV envelope. The 120 in its name comes from its molecular weight of 120 kilodaltons...

 CD4 binding site. This protein is common to all HIV variants as it is the attachment point for B lymphocytes
B cell
B cells are lymphocytes that play a large role in the humoral immune response . The principal functions of B cells are to make antibodies against antigens, perform the role of antigen-presenting cells and eventually develop into memory B cells after activation by antigen interaction...

 and subsequent compromising of the immune system.

Researchers from the Hebrew University of Jerusalem
Hebrew University of Jerusalem
The Hebrew University of Jerusalem ; ; abbreviated HUJI) is Israel's second-oldest university, after the Technion – Israel Institute of Technology. The Hebrew University has three campuses in Jerusalem and one in Rehovot. The world's largest Jewish studies library is located on its Edmond J...

 have also discovered that a combination of peptide
Peptide
Peptides are short polymers of amino acid monomers linked by peptide bonds. They are distinguished from proteins on the basis of size, typically containing less than 50 monomer units. The shortest peptides are dipeptides, consisting of two amino acids joined by a single peptide bond...

s that stimulate integration together with the protease inhibitor
Protease inhibitor (pharmacology)
Protease inhibitors are a class of drugs used to treat or prevent infection by viruses, including HIV and Hepatitis C. PIs prevent viral replication by inhibiting the activity of proteases, e.g.HIV-1 protease, enzymes used by the viruses to cleave nascent proteins for final assembly of new...

 Ro 31-8959 caused apoptotic cell death of HIV-infected cells with total extermination of the virus but did not harm healthy cells. It could take several years before a commercial treatment based on this discovery becomes available.

Reactivation of the retrocyclin pseudogene
Pseudogene
Pseudogenes are dysfunctional relatives of known genes that have lost their protein-coding ability or are otherwise no longer expressed in the cell...

 has been proposed as a possible prevention method, as was demonstrated in a proof-of-concept study in tissue culture cells.

In Berlin
Berlin
Berlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...

, Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

, a 42-year-old leukemia
Leukemia
Leukemia or leukaemia is a type of cancer of the blood or bone marrow characterized by an abnormal increase of immature white blood cells called "blasts". Leukemia is a broad term covering a spectrum of diseases...

 patient, Timothy Ray Brown (also referred to as the "Berlin Patient"), infected with HIV for more than a decade was given an experimental transplant of bone marrow with cells that contained an unusual natural variant of the CCR5
CCR5
C-C chemokine receptor type 5, also known as CCR5, is a protein that in humans is encoded by the CCR5 gene. CCR5 is a member of the beta chemokine receptors family of integral membrane proteins...

 cell-surface receptor. This CCR5-Δ32 variant has been shown to make some cells from people who are born with it resistant to infection with some strains of HIV. Almost two years after the transplant, and even after the patient reportedly stopped taking antiretroviral medications, HIV has not been detected in the patient's blood. As of December 2010, three years after the transplant, Brown was still free of any detectable HIV in his blood and was described, in a paper in the journal Blood, as "cured. "

External links