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  Wikipedia: AIDS

Wikipedia: AIDS
AIDS
From Wikipedia, the free encyclopedia.

AIDS (occasionally spelled Aids), is a disease of humans, which has been epidemic since it was first detected in the early 1980s. Initially seen as a disease occurring in homosexual men and intravenous drug users, by the 1990s it had become a global epidemic, primarily affecting heterosexual men and women, and also children, in developing countries.

Definitions

AIDS stands for Acquired Immuno-deficiency Syndrome or Acquired Immune Deficiency Syndrome. The name refers to a syndrome (group of symptoms) which cause immune deficiency: the progressive destruction of the body's immune system, and which is acquired. The cause of this acquired immune deficiency was initially unknown, but is now believed by the overwhelming majority of medical opinion to result from infection with a retrovirus called the Human Immunodeficiency Virus (HIV), transmitted by bodily fluids such as blood, semen and vaginal secretions.

AIDS is currently considered incurable, but is generally treated as a long-term illness. Treatment of the disease in the United States and other western countries has greatly improved over the past decade, and there are people who have lived with AIDS for ten to twenty years. In poorer countries, AIDS treatments are generally not available, and most people with AIDS die within a few years of diagnosis.

Since most of the original 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 transfusions recipients, and heterosexual women. The disease was officially given the carefully neutral name AIDS in 1982.

Early years of the epidemic

The era of AIDS officially began in July 1981, when the CDC (Centers for Disease Control) issued a press release describing a clustering of cases of Kaposi's sarcoma (KS), a relatively unusual skin cancer, and Pneumocystis carinii pneumonia (PCP) in Los Angeles, New York City, and San Francisco. The first report of these unusual cases had been reported 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 cells or T-cells. Many of the patients died within a few months.

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 gay men with AIDS known as the "Los Angeles cluster" was described: a group of nine gay 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. 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 SIV, a virus 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 (this theory 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, Patient Zero, a Canadian flight attendant who was said to have had sex with over 1,000 men in various countries, and this became the subject of a movie. This theory, popularised by the gay journalist Randy Shilts in his book And the Band Played On, has been disproven.

In 1984 two scientists, Dr Robert Gallo in the United States and Professor 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 because of protests by the parents of other children was forced to withdraw from school. Sufferers were isolated; people were afraid to be close to them as many mistakenly 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. 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 since birth control was unnecessary with same-sex partners, gay men were unlikely to use condoms, now considered one of the best ways 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.

Description of Symptoms

HIV causes disease by infecting the CD4 T cells. These are a subset of leukocytes (white blood cells) that normally co-ordinate the immune response to infection. T cells are part of the immune system and important in fighting infection and cancer. Once an HIV-infected individual's CD4 T cell count has decreased to a certain threshold, they are prone to a range of diseases that the body can normally control. These include cancers and opportunistic infections, which are usually the cause of death. HIV also infects brain cells, causing some neurological disorders.

There are a large number of illnesses which are accepted as "AIDS-defining":

  • candidiasis, oesophageal, lungs or disseminated
  • 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
  • isosporiasis, chronic intestinal
  • Kaposi's sarcoma
  • lymphoma, Burkitt's or primary lymphoma of the brain
  • mycobacterium avium complex infection or M. kansasii infection, disseminated or extrapulmonary mycobacterium tuberculosis, disseminated, any site
  • Mycobacterium, other species, disseminated or extrapulmonary
  • Pneumocystis carinii pneumonia (PCP)
  • Salmonella septicemia, recurrent
  • toxoplasmosis, neurological

Current medical understanding of AIDS

HIV is closely related to viruses causing AIDS-like diseases in many primates, and is generally thought to have been transferred from animals to humans at some time during the early 20th century, though some evidence suggests it may have been transferred earlier in several isolated cases. The exact animal source, time, and location of the transfer (or indeed, how many transfers there were) is not currently known. A virus virtually identical to human HIV (known as Simian Immunodeficiency Virus (SIV) has been found in chimpanzees, but it is not known for certain whether the transmission was from chimpanzees to humans, or whether both chimpanzees and humans were infected by a third source.

Studies suggest that the virus spread initially in West Africa, but it is possible that there were several separate initial sources. The earliest human fluid sample known to contain HIV was taken in 1959 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.

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 can also be transmitted from mother to unborn child. Blood transfusions and the use of blood products to treat hemophilia 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 a minimum CD4 cell count and the presence of opportunistic infections.

The CD4 (thymus-derived cell or lymphocyte) count is a measure of the HIV target cells in the blood. A count below 200 per cubic millimetre is usually considered as one criterion for a diagnosis of AIDS. The occurrence of opportunistic infections (see below), caused by agents usually unable to induce diseases in healthy people, is another criterion. Helper cell counts can fluctuate, and opportunistic infections can sometimes be overcome, so a diagnosis of AIDS may be fluid.

A person who is infected with HIV is said to be HIV+ (HIV positive) and is sometimes referred to as a PWH, or Person With HIV. An uninfected individual is said to be HIV- (HIV negative). HIV+ individuals are frequently unaware of their HIV status. Persons with AIDS (PWAs) are also sometimes 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.

Infection with HIV is called seroconversion, and may be accompanied by what is called "seroconversion illness" (an earlier term was "AIDS prodrome"). This usually includes mild flu-like symptoms such as fever, aching muscles and joints, sore throat, and swollen glands (lymph nodes), by other symptoms, or by no symptoms at all. Regardless of the presence or absence of initial symptoms, all newly infected individuals become asymptomatic (symptom-free).

During the asymptomatic stage, billions of HIV particles are produced every day accompanied by a decline (at variable rates) in the number of CD4 cells. The virus is not only present in the blood, but also throughout the body, particularly in the lymph nodes, brain, and genital secretions.

The time from HIV infection to the development of AIDS varies. Some patients develop symptoms within a few months of infection, while others are known to have remained completely symptom-free for as long as 20 years. The reason why different people advance at various rates is currently unknown. The average time for progression from initial infection to AIDS is 8 to 10 years in the absence of treatment.

Treatments and vaccines

There is currently no cure for 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 treatments in prolonging life, and improving quality of life, for people with AIDS has improved dramatically.

Current treatment options primarily include combinations ("cocktails") of two or more nucleoside analogue reverse transcriptase inhibitors (NRTIs), and a protease inhibitor. Patients on such treatments have been known to repeatedly test "undetectable" 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.

Ongoing research is examining methods of simplifying drug regimens (which often require patients to take large numbers of pills at prescribed intervals several times a day) to improve adherence and decrease side effects. New drugs are also being developed. Also, methods of purging HIV from the body are being researched. Researchers are also attempting to create an HIV vaccine, and human trials are currently underway.

Ever since AIDS began, 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 people with AIDS experimented with alternative therapies of various kinds. None of these were shown to be of genuine or long-term benefit in controlled trials. 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 and to stimulate appetite. This practice is currently illegal in most jurisdictions.

Alternative theories

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. 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.

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. 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. (See AIDS reappraisal for further discussion of this issue.)

Current status

By the turn of the 21st century AIDS had become a global epidemic, affecting people in virtually every country, and in most countries it shows no signs of slowing down. It is estimated that over 40 million people worldwide are HIV-positive and about 13 million have already died from AIDS-related illnesses.

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 concurrent sexually transmitted disease 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 safe 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 (especially 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. Some countries in Africa now have around 25% of the working adult population who are HIV-positive, the highest being Botswana with 35.8% (1999 estimate - source World Press Review). See AIDS in Africa. The situation in South Africa, where President Thabo Mbeki shares the views of the "AIDS denialists," is also deteriorating rapidly.

AIDS is also rising steadily in Asia. As of July 2003, India's HIV-positive people numbered about 4.6 million, roughly 0.9% of the working adult population. In China the number was roughly from 1 million to 1.5 million, with some estimates going much higher. AIDS seems to be under control in Thailand and Cambodia, but new infections occur in those nations at a steady rate.

Prevention of AIDS

HIV cannot be transmitted by breathing, via casual contact such as touching, holding or shaking hands, hugging, and kissing, or via mutual masturbation, or by sharing cooking and eating utensils, dishes, cups and glasses. The only proven cause of transmission is the exchange of bodily fluids. Despite widely publicised fears about the possible "casual tranmission" of AIDS, HIV infection is preventable by following simple precautions.

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 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 HIV for sexually active people. 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, the use of water-based lubricants is recommended. Condoms are not compatible with oil-based lubricants.

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, but 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. All AIDS-prevention organisations advise drug-users not to share needles and to use new 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 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 needlestick is less than 1 in 200. Post-exposure prophylaxis with anti-HIV drugs can further reduce that small risk.

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From Wikipedia, the free encyclopedia. 
Modified by Geona