AIDS (the acronym meaning Acquired Immunodeficiency Syndrome or Acquired Immune Deficiency Syndrome, and occasionally written as Aids) is a human disease characterized by progressive destruction of the body's immune system. It is believed by the overwhelming majority of medical opinion to result from infection with HIV, the Human Immunodeficiency Virus (which is actually a retrovirus).
AIDS was first noticed among homosexual men and intravenous drug users in the 1980s.By the 1990s the syndrome had become a global epidemic and in 2004, 58% of those with AIDS were women. While homosexual men continue to suffer higher per capita AIDS rates, the majority of victims are currently heterosexual women, men, and children in developing countries.
AIDS is currently considered incurable; where treatments are unavailable (mostly in poorer countries) most sufferers die within a few years of diagnosis. In the developed countries, treatment has improved greatly over the past decade, and people have lived with AIDS for ten to twenty years.
__Symptoms__
HIV is transmitted by bodily fluids, such as blood, semen and vaginal secretions. It causes disease by infecting CD4 T cells, a type of leukocyte (white blood cell) that normally co-ordinates the immune response to infection and cancer. When a person's CD4 T cell count decreases sufficiently he or she is prone to a range of diseases that a healthy person's body is normally able to fight. These diseases include cancers and opportunistic infections, which are usually the cause of death in persons with AIDS. HIV also infects brain cells, causing some neurological disorders.
Originally AIDS was diagnosed based on the opportunistic diseases affecting the patient. Today, diagnosis is based on CD4 T cell counts. This allows for earlier diagnosis and better representation of women.
Many opportunistic diseases are associated with AIDS:
* candidiasis, disseminated or of the oesophagus and/or lungs
* coccidiodomycosis, disseminated or extrapulmonary
* cryptococcosis, extrapulmonary
* cryptosporidiosis, chronic intestinal
* cytomegalovirus (CMV) disease, disseminated or CMV retinitis
* herpes simplex virus (HSV) infection, chronic or HSV bronchitis, pneumonitis or esophagitis
* histoplasmosis, either disseminated or extrapulmonary
* HIV-related dementia or encephalopathy
* chronic intestinal isosporiasis
* Kaposi's sarcoma (KS)
* lymphoma, Burkitt's or primary lymphoma of the brain ("AIDS-related lymphoma")
* Mycobacterium avium complex (MAC) infection or M. kansasii infection, disseminated or extrapulmonary Mycobacterium tuberculosis, disseminated, any site
* Mycobacterium, other species, disseminated or extrapulmonary
* Pneumocystis carinii pneumonia (PCP)
* progressive multifocal leukoencephalopathy (PML)
* recurrent salmonella septicaemia
* neurological toxoplasmosis.
__History__
Though the earliest confirmed AIDS case--then unrecognized as such--dates from 1959, the first official recognition of AIDS was on June 5, 1981, when the American (Centers for Disease Control) issued a press release describing five cases of Pneumocystis carinii pneumonia in Los Angeles.
The following month, cases of Kaposi's Sarcoma, a skin cancer, were reported. The first reports of these unusual cases were made to the CDC by Dr Michael Gottlieb of San Francisco.
While KS and PCP were not unknown to physicians, the tight clustering of cases was considered highly unusual. Most patients identified were sexually active homosexual men, many of whom were also discovered to be suffering from other chronic diseases later identified as opportunistic infections. Blood tests revealed that many of the patients were also lacking in adequate numbers of a class of white blood cells called CD4 T cells. Many of the patients died within a few months.
Since most of the originally identified sufferers were homosexual men, the syndrome was initially referred to by doctors as "GRID" (Gay-Related Immune Deficiency), and was referred to in some sections of the media as "the gay plague." Almost at once, however, it was realised that the infected population included Haitian immigrants, intravenous drug users, blood transfusion recipients, and heterosexual women as well. The disease was officially renamed AIDS in 1982.
Until 1984, there were a number of theories about the possible causes of AIDS. The most widely held theory, right from the start, was that AIDS was caused by a virus. The evidence for this was mainly epidemiological. In 1983 a group of nine gay male AIDS patients in Los Angeles with interlocking sexual contacts, including a sexual contact in New York shared by three of the Los Angeles men who were strangers to each other was described; this group became known as the "Los Angeles Cluster." This pattern immediately suggested that an infectious agent was responsible.
Other possible theories at this time included the "immune overload" theory, popularised in the gay press by the activist Michael Callen. This theory suggested that AIDS arose from the effects of excessive drug use and sexual promiscuity among so-called "fast lane" gay men. It was also suggested that the anal intake of semen during anal sex, when combined with the use of nitrite inhalants (known as "poppers"), might suppress the immune system. Few medical specialists accepted these theories, but they became established among non-medical commentators and are still promoted by some of those who deny that HIV causes AIDS.
In the early years of AIDS, the exact origin of the virus causing AIDS was unknown. A common theory, which even became the subject of an article in Rolling Stone Magazine, held that HIV came from Simian Immunodeficiency Virus (SIV), a virus virually identical to HIV, that causes AIDS-like symptoms in primates, and that this virus was transmitted to human populations in Africa during the course of controversial polio vaccine experiments on African villagers. The theory that the virus was transmitted during the polio vaccine experiments has since been disproven.
It was also commonly believed that the spread of AIDS to the western world was attributable to the sexual behaviour of a single man known as Patient Zero, a Canadian flight attendant who was said to have had sex with over 1,000 men in various countries. This theory, popularised by the gay journalist Randy Shilts in his book And the Band Played On, and later made into a movie, has since been disproven.
In 1984 two scientists, Dr Robert Gallo in the United States and Professor Jean Luc Montagnier in France, independently isolated the virus which causes AIDS. After a prolonged dispute, they agreed to share credit for its discovery, and it was given the name Human Immunodeficiency Virus (HIV) in 1986. The discovery of the virus allowed the rapid development of an antibody test, which allowed people at risk to know whether they were infected and therefore at risk of developing AIDS. It also allowed research on possible treatments and a possible vaccine to begin.
Sufferers of AIDS in the early days were frequently ostracized by their communities, friends, and even families. Ryan White, for example, was a young American boy who contracted AIDS through a blood transfusion, and was forced to withdraw from school because of protests by the parents of other children. Sufferers were isolated; people were afraid to be close to them as it was commonly believed that AIDS could be transmitted by casual contact such as holding hands, kissing, hugging, or sharing cups, dishes or eating utensils.
Gay men were frequently blamed for the advent and spread of AIDS in the West. (See also AIDS in the United States.) Some claimed that AIDS was a punishment from God for homosexuality (this belief is still espoused by some religious groups, both Christian and Islamic). Others claimed that the "depraved lifestyles" of gay men were responsible. It is true that in the early years AIDS spread quickly through gay communities and that a majority of early sufferers were gay men, but this is in part due to the fact that birth control was unnecessary with same-sex partners so gay men were unlikely to use condoms, now considered one of the best ways (other than abstinence) to prevent the spread of HIV.
The initial focus on gay men proved very damaging since it distracted attention from the rapid spread of HIV infection among heterosexuals, particularly in Africa and the Caribbean, and later in parts of Asia, and, some believe, because institutionalized homophobia prevented quick action against HIV and AIDS.
__Origins of AIDS__
HIV is closely related to the simian immunodeficiency viruses (SIV). The SIV are lentiviruses, like HIV, and are endemic to many African monkeys and apes, in which they are largely asymptomatic. Most scientists believe that one or more SIV were transferred from animals to humans at some time during the early 20th century. Research conducted in 1999 at the University of Alabama found that HIV-1 was very similar to the chimpanzee SIV (SIVcpz). The exact animal source, time, and location of the transfer (or indeed, how many transfers there were) is not currently known and is the subject of research and controversy. It may be possible that both humans and chimpanzees were infected from a third source.
The natural transfer hypothesis proposes that SIV was transferred to humans due to the natural interaction between human and primate populations. The hunting of monkeys for bushmeat, the so-called "cut hunter" theory, is one possible route. Another is the consumption of raw animal flesh, supposing oral transmission.
Studies suggest that the virus spread initially in West Africa, but it is possible that there were several separate initial sources, corresponding to the different strains of HIV (HIV-1 and HIV-2). The earliest human fluid sample known to contain HIV was taken in 1959 from a British sailor, who apparently contracted it in what is now the Democratic Republic of the Congo. Other early samples include one from an American male who died in 1969, and a Norwegian sailor in 1976. It is believed that the virus was spread via sexual activity, possibly including with prostitutes, in Africa's rapidly growing urban areas. As unwittingly infected people traveled the virus spread from one city to another, and air travelers carried the virus to other continents.
Recently, evidence has grown that AIDS may have been introduced by the United Nations oral polio vaccination program in Africa during the late 1950s. The OPV AIDS hypothesis argues that the use of monkey and chimpanzee organs to prepare vaccines provides a possible mechanism for the introduction of SIV into humans, particularly considering that the vaccines were administered to a million people, many of them young infants with weak immune systems. Many scientists dispute this theory, arguing that is unlikely, but it has yet to be disproven.
__Current medical understanding of AIDS__
Currently the most common ways to contract HIV are via unprotected sexual activity and the sharing of needles by users of intravenous drugs. The virus is rarely transmitted from mother to child in the womb, but HIV can be transmitted during childbirth or through breastfeeding. Blood transfusions and the use of blood products to treat haemophilia have also been major routes of infection in the past, leading to stricter screening procedures (but despite these new measures such cases are still reported occasionally).
Not every patient who is infected with HIV is considered to have AIDS. The criteria for a diagnosis of AIDS can vary from region to region, but a diagnosis typically requires either:
* an absolute CD4 cell count below 200 per cubic millimetre, or
* the presence of opportunistic infections, caused by agents usually unable to induce diseases in healthy people
A person who is infected with HIV is said to be HIV (HIV positive or seropositive) and is sometimes referred to as a PWH, or Person With HIV. An uninfected individual is said to be HIV- (HIV negative or seronegative). HIV individuals are frequently unaware of their HIV status. Persons with AIDS (PWAs) are also said to be HIV , and PWHs and PWAs are sometimes collectively referred to as PWAs or PWH/As. In recent years the more optimistic term "People Living With AIDS" (PLWAs) has come to be preferred by AIDS activist groups and many people with AIDS themselves.
Primary infection with HIV is called seroconversion, and may be accompanied by what is called "seroconversion illness" (an earlier term was "AIDS prodrome"). Symptoms of seroconversion illness include mild flu-like symptoms such as fever, aching muscles and joints, sore throat, and swollen glands (lymph nodes), but may also include other symptoms such as rash. Not every person who seroconverts experiences seroconversion illness, and there are people who experience no symptoms at all at this stage.
Regardless of the presence or absence of initial symptoms, all newly infected individuals become asymptomatic (symptom-free). The newly infected patient is actually most infectious during the seroconversion illness as it is during this time that the HIV viral load in the blood plasma is highest. At this stage, the virus is still multiplying rapidly, unchecked, because the body has not yet started to produce antibodies to the virus in sufficient quantities to reach an equilibrium.
During the asymptomatic stage, billions of HIV particles are produced every day accompanied by a decline, at variable rates, in the number of CD4 T cells. The virus is not only present in the blood, but also throughout the body, particularly in the lymph nodes, brain, and genital secretions. During this stage, the body's immune system is actively trying to fight off the HIV infection but, for the vast majority of infected people who are not receiving treatment, the immune response is insufficient as the virus directly attacks cells of the immune system and mutates rapidly.
The time from infection with HIV to a diagnosis of AIDS varies. Some patients develop symptoms within a few months of infection, while others are known to have remained completely asymptomatic for as long as 20 years. These people who remain asymptomatic are often called Long-term AIDS nonprogressors. Why these nonprogressors remain AIDS-free, and why different people advance at various rates, is currently unknown, and is the subject of ongoing study. The average time of progression from initial infection to AIDS is eight to ten years in the absence of treatment.
__Treatments and vaccines__
There is currently no cure or vaccine for HIV or AIDS. Newer treatments, however, have played a part in delaying the onset of AIDS, on reducing the symptoms, and extending patients' life spans. Over the past decade the success of these anti-retroviral treatments in prolonging, and improving, the quality of life for people with AIDS has improved dramatically.
Current optimal treatment options consist of combinations ("cocktails") of two or more types of anti-retroviral agents such as two nucleoside analogue reverse transcriptase inhibitors (NRTIs), and a protease inhibitor. Patients on such treatments have been known to repeatedly test "undetectable" (that is, negative) for HIV, but discontinuing therapy has thus far caused all such patients' viral loads to promptly increase. There is also concern with such regimens that drug resistance will eventually develop. In recent years the term HAART (highly-active anti-retroviral therapy) has been commonly used to describe this form of treatment. The majority of the world's infected individuals, unfortunately, do not have access to medications and treatments for HIV and AIDS.
There is ongoing research into developing a vaccine for HIV and in developing new anti-retroviral drugs. Human trials are currently underway. Research to improve current treatments includes simplifying current drug regimens to improve adherence and in decreasing side effects.
Ever since AIDS entered the public consciousness, various forms of alternative medicine have been used to treat its symptoms. In the first decade of the epidemic when no useful conventional treatment was available, a large number of PWAs experimented with alternative therapies of various kinds, including massage, herbal and flower remedies and acupuncture, to either combat the virus or to relieve related symptoms. None of these were shown to have any genuine or long-term effect on the virus in controlled trials, but they may have had other quality of life-enhancing effects on individual users. Interest in these therapies has declined over the past decade as conventional treatments have improved. They are still used by some people with AIDS who do not believe that HIV causes AIDS. Alternative therapies such as massage, acupuncture and herbal medicine are still used by many sufferers in conjunction with other treatments, mainly to treat symptoms such as pain and loss of appetite. People with AIDS, like people with other illnesses such as cancer, also sometimes use marijuana to treat pain, combat nausea and stimulate appetite.
__AIDS reappraisal__
A few scientists and AIDS activists continue to question the connection between HIV and AIDS, the very existence of HIV, or of an independent AIDS disease. The validity of current testing methods is also questioned. Dissident scientists report that they are usually not invited to attend AIDS conferences and are not granted research funding from most mainstream sources. Prominent members of this group are virus researcher Peter Duesberg and Nobel Prize laureate Kary Mullis. These theories have been in the field for at least 15 years, and have found no support beyond the original circle of advocates. They gained prominence when they were promoted, for reasons which have never been made clear, by sections of the Murdoch press, such as the Sunday Times of London and The Australian of Sydney.
A now deceased Dr. Robert E. Willner caught the attention of the Spanish media, when in 1993 he innoculated himself with the blood of Pedro Tocino, an HIV positive hemophiliac on live TV. His book "The Proof That Sex And HIV Absolutely Do Not Cause AIDS" is controversial to say the least.
Mainstream AIDS activists characterize the position of these dissidents as "AIDS denialism," and believe their public proselytization for their various theories is destructive to the adoption of appropriate preventive and therapeutic measures. Active advocacy of these theories is largely confined to radical gay activist groups such as ACT-UP in San Francisco. (Not to be confused with ACT-UP/Golden Gate, which split from ACT-UP San Francisco in 1990, and changed its name in 2000 to avoid association with ACT-UP/San Francisco's non-mainstream views). As with the enthusiasm for alternative therapies, advocacy of unorthodox views about AIDS has declined with the increasing success of orthodox medical approaches to AIDS therapies.
__Current status__
By the turn of the 21st century AIDS had become a global epidemic, affecting people in virtually every country, and in many countries it shows no signs of slowing down. It is estimated that by 2003 over 40 million people worldwide were HIV-positive and that about 19 million had died from AIDS-related illnesses. These numbers have led some experts to call AIDS the deadliest pandemic in human history since the Black Death of the 14th century.
In Western countries the infection rate of HIV has slowed somewhat, due to the widespread adoption of safe sex practices by gay men and (to a lesser extent) the existence of needle exchanges and campaigns to educate intravenous drug users about the dangers of sharing needles. The spread of infection among heterosexuals in western countries has also been much slower than originally feared, possibly because HIV is less readily transmissible through vaginal sex without other concurrent sexually transmitted diseases than was initially believed.
In some populations, however, such as young urban gay men, infection rates began to show signs of rising again from the late 1990s. In Britain the number of people diagnosed with HIV increased 26% from 2000 to 2001. Similar trends have been seen in the United States and Australia, and are attributed to "AIDS fatigue" among younger gay men who have no memory of the worst phase of the epidemic in the 1980s as well as "condom fatigue" among those who have grown tired of and dissillusioned with the unrelenting safer sex message. This trend is of major concern to public health workers. AIDS continues to be a problem with illegal sex workers and injection drug users. On the other hand, the death rate from AIDS in all Western countries has fallen sharply, as new AIDS therapies have proven to be an effective (if expensive) means of suppressing HIV.
In developing countries, in particular Sub-Saharan Africa, however, poor economic conditions (leading to the use of dirty needles in healthcare clinics) and lack of sex education means continued high infection rates (see AIDS in Africa). In some countries in Africa 25% or more of the working adult population is HIV-positive; in Botswana alone the figure is 35.8% (1999 estimate — source World Press Review (http://www.worldpress.org/map.htm)). The situation in South Africa, where President Thabo Mbeki shares the views of the "AIDS denialists," is also deteriorating rapidly, with 4.7 million infections in 2002. Also suffering heavily are Nigeria and Ethiopia, which had 3.7 million and 2.4 million people infected respectively in 2003. On the other hand Uganda, Zambia, and Senegal have initiated prevention programs to reduce their HIV infection rates, with varying degrees of success.
Latin America and the Caribbean had just over 2.2 million infected persons in 2003, with modes of transmission and infection rates varying widely. The infection rates are highest in Central America and the Caribbean, where heterosexual transmission is fairly common. In Mexico, Brazil, Colombia, and Argentina, drug injection and homosexual activity are the main modes of transmission, but there is concern that heterosexual activity may soon become a primary method of spreading the virus. Brazil recently began a comprehensive AIDS prevention and treatment program to keep the AIDS virus in check, including the production of generic versions of anti-retroviral drugs.
AIDS infection rates are also rising steadily in Asia, with over 7.5 million infections by 2003. In July 2003, the estimated number of HIV individuals in India was about 4.6 million, roughly 0.9% of the working adult population. In China, the number was estimated at 1 million to 1.5 million, with some estimates going much higher. Both countries have growing epidemics spread by large numbers of urban sex workers (a technical term for prostitute) and intravenous drug use. China also suffers from an epidemic in some of its rural areas, where large numbers of farmers, especially in Henan province, participated in sloppy procedures for blood transfusions; estimates of those infected are in the tens of thousands. AIDS seems to be under control in Thailand and Cambodia, but new infections occur in those nations at a steady rate.
There is also growing concern about a rapidly growing epidemic in Eastern Europe and Central Asia, where an estimated 1.7 million people were infected by January 2004. The rate of HIV infections rose rapidly from the mid-1990s, due to social and economic collapse, increased levels of intravenous drug use and increased numbers of prostitutes. By 2004 the number of reported cases in Russia was over 257,000, according to the World Health Organization, up from 15,000 in 1995 and 190,000 in 2002; some estimates claim the real number is up to five times higher, over 1 million. Ukraine and Estonia also had growing numbers of infected people, with estimates of 500,000 and 3,700 respectively in 2004.
__Prevention__
Despite widely publicised fears about the possible "casual transmission" of HIV and AIDS, the risk of infection is virtually eliminated by following simple precautions and is entirely eliminated by abstaining from sexual activity and avoiding blood transfusions and the sharing of needles.
The only proven cause of transmission is the exchange of bodily fluids, in particular blood and genital secretions. HIV cannot be transmitted by breathing, via casual contact such as touching, holding or shaking hands, hugging and kissing, by mutual masturbation, or by sharing cooking and eating utensils, dishes, cups and glasses. It is possible that HIV could be transmitted through open-mouthed kissing if both partners had bleeding oral sores, but no such case has been documented and the possibility of transmission in this way is considered very unlikely as saliva contains much lower concentrations of HIV than, for example, semen, and also because saliva contains antiviral properties which kill HIV.
HIV transmission via sexual activity has been recorded from male to male, male to female, female to female and female to male. The use of latex condoms is recommended for all penetrative sexual activity. Condoms are not 100% effective against pregnancy or disease transmission, but if used correctly they are the best means of protection against the sexual transmission of HIV. It has been repeatedly shown that HIV cannot pass through latex condoms.
Anal sex, because of the delicacy of the tissues in the anus and the ease with which they can tear, is considered the highest-risk sexual activity, but condoms are recommended for vaginal sex as well. Condoms should be used only once, and then thrown away and a new condom used each time. Because of the risk of tearing (both of the condom and of skin and mucous membranes), the use of water-based lubricants is recommended. Oil-based lubricants should not be used with condoms as they can cause tears in the condom material by weakening the latex.
There have been claims that a small number of people have been infected with HIV from performing oral sex on an infected partner, but these claims are disputed in the scientific community and have yet to be proven conclusively. Oral sex is considered a very low risk activity, since it has been shown that both saliva and stomach acid have antiviral properties which kill HIV. Nevertheless, it is usually recommended not to take semen into the mouth. The use of condoms (or dental dams for cunnilingus) further reduces the potential risk.
HIV is known to be transmitted via the sharing of needles by users of intravenous drugs, and this is one of the most common methods of transmission. All AIDS-prevention organisations advise drug-users not to share needles and to use a new or properly sterilized needle for each injection. Information on cleaning needles using bleach is available from health care and addiction professionals and from needle exchanges. In the United States and other western countries, clean needles are available free in some cities, at needle exchanges or safe injection sites.
Medical workers who follow universal precautions or body substance isolation such as wearing latex gloves when giving injections or handling bodily wastes or fluids, and washing the hands frequently, can prevent the spread of HIV from patients to workers, and from patient to patient. 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 less than 1 in 200. Post-exposure prophylaxis with anti-HIV drugs can further reduce that small risk.
A recent study has shown that circumcised men may be slightly less likely to contract HIV, but a conclusive study has yet to be done. The current theory is that cells in the foreskin which are removed during circumcision act as so-called "HIV receptors." The difference at present appears to be very slight, and it is unlikely that these findings will lead to an increase in elective newborn circumcisions, which are currently performed as a matter of course only in the United States. Being circumcised should not be taken as having immunity to HIV.
There is now some evidence that treatment of already-infected people with antiretroviral drugs may reduce the transmission of HIV infection to their sexual partners, independently of other safer-sex precautions. This may imply that aggressively treating existing HIV cases, in addition to protecting the uninfected population through education and safer-sex programs, may be more effective at preventing the spread of HIV that either of these alone.