AIDS

The factual accuracy of this article is disputed: see talk:AIDS

Acquired ImmunoDeficiency Syndrome (AIDS) is the name given in 1981 to a newly emerging medical condition, a syndrome (group of symptoms) now known to arise from the progressive destruction of the body's immune system. This destruction is caused by infection with the Human Immunodeficiency Virus (HIV), a virus transmitted through bodily fluids such as blood and semen.

Table of contents

1 Infection
2 HIV and AIDS
3 Origin and description of symptoms

3.1 AIDS defining illnesses

4 AIDS Prevention
5 AIDS Treatment
6 Alternative theories
7 Origin of the virus
8 Early Years of the Epidemic
9 Current Status
10 Immunity
11 Related Articles

Infection

The most common ways to contract HIV include unprotected sexual activity and the use of unsterilized needles by users of intravenous recreational drugs. The virus can also be transmitted from mother to unborn child. Blood transfusions of contaminated blood as well as blood products to treat hemophilia have also been major routes of infection in the past, leading to stricter screening procedures.

HIV and AIDS

Not everyone who is infected with HIV is considered to have AIDS. The AIDS diagnosis is usually made when a certain level of damage has been done to the immune system and is defined by the occurrence of opportunistic infections. Opportunistic infections are caused by agents usually unable to induce diseases in healthy humans. Up until that point, the person is considered simply HIV-positive. The immune damage can be quantified by the decrease of the helper T cell count, the HIV target cells in the blood. A count below 200 per cubic millimetre is considered as one criterion for AIDS.

Right after HIV infection a mild disease (seroconversion) develops, which passes when killer T cells begin to suppress the virus, shortly before the body produces antibodies. In the absence of any kind of treatment, AIDS (HIV-induced immune system collapse) develops on average 10 years later, although the documented range is as short as 2 years and as long as about 18. Death usually occurs some 2 years after the onset of AIDS. Newer anti-retroviral cocktail treatments have played a part in delaying the onset of AIDS or reducing the symptoms of AIDS.

Origin and description of symptoms

HIV causes disease by infecting the CD4+ T cells (which are also called T4 cells or helper T cells). These are a subset of leukocytes (white blood cells) that normally coordinate the immune response to infection. T cells are part of the immune system and important in fighting infection and cancer. Once a HIV+ 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.

AIDS defining illnesses

There are several accepted AIDS defining illnesses which include:

various infections:
- 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
- isosporiasis, chronic intestinal
- 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
various cancers:
- Kaposi's sarcoma
- lymphoma, Burkitt's or primary lymphoma of the brain
HIV dementia or encephalopathy

AIDS Prevention

HIV infection is entirely preventable by following simple, basic precautions. The only known cause of transmission is the exchange of bodily fluids.

Use a condom during all sexual activity. Anal sex is a particularly high-risk behavior. A few people have been infected with HIV from giving oral sex to an infected partner, but it is considered very low risk. If you want to be absolutely certain you're safe, use a condom (or dental dam for cunnilingus) even during oral sex. See also: Safer sex.
Do not share needles. If you use drugs intravenously, such as heroin, do not share your needle with someone else, and do not use a needle that has been used by others. In many places you can find a local needle exchange program where you can trade a used needle for a clean one, without any legal hassles.
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.

Only minute amounts of the virus are present in saliva and sweat, and activities such as kissing, sharing glasses or shaking hands are generally considered to be safe.

AIDS Treatment

There is still no known cure for AIDS, and many people still die every year, particularly in Third World countries where treatments are either not available or prohibitively expensive. Current and experimental treatments for AIDS are covered in the HIV section. Work on a vaccine continues, but progress has been slow.

Alternative theories

A few scientists 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. Their opponents often characterize their position as "AIDS denialism" and believe their public proselytization for their various theories is destructive to the adoption of appropriate preventive and therapeutic measures.

See AIDS reappraisal.

Origin of the virus

HIV is closely related to viruses causing AIDS-like diseases in many primates, and it is generally believed 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 known. A virus virtually identical to human HIV (known as Simian Immunodeficiency Virus, or SIV) has been found in chimpanzees, but it is not certain that the transfer was from chimps to humans or whether both chimps and humans were infected from a third source.

Scientific studies have suggested the virus spread initially in West Africa, but it is possible that there were several separate "initial sources", including somewhere in South America. The earliest 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.

Most scientists believe that the spread of the virus was slow at first. When infected people visited prostitutes in Africa's rapidly growing urban areas, however, the spread of the virus began to accelerate. Truckers and other travelers infected by the prostitutes spread the virus from one city to another in many parts of Africa. Infected air travelers unwittingly spread the virus to other continents.

A misconception holds that the virus was introduced to North America by one person, Patient Zero.

Early Years of the Epidemic

The era of AIDS officially begins in July 1981, when the CDC issued a press release describing the clustering of cases of Kaposi's Sarcoma in Los Angeles, New York City, and San Francisco. Kaposi's Sarcoma wasn't unknown to physicians at the time, but the tight clustering of cases was. Most were homosexual men who were sexually active, and many were also found to suffer from other chronic diseases that were later identified as opportunistic infections. Subsequent blood tests revealed that many were lacking in adequate numbers of CD4+ T cells. Despite determined attempts to find a cure many of these victims died within a few months of diagnosis.

At first the then-unknown syndrome was referred to as GRID (Gay-Related Immune Deficiency). However, as similar disorders were diagnosed amongst Haitian immigrants, intravenous drug users, and patients who had received blood transfusions, scientists realized they had a more complicated disease than had been previously thought. By the end of 1982, the disease had received its present name to better reflect its multifaceted nature.

Current Status

As of the year 2002 AIDS is a global pandemic, and 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 disease, mainly tuberculosis. If such trends continue it is likely that the global death toll for AIDS will be comparable to other plagues such as the Black Death and the Spanish Flu.

In Western countries, the infection rate of HIV has slowed somewhat, due to education of safe sex practices. In some populations, however, such as young urban gay men, infection rates show signs of rising again. In Britain the number of people diagnosed with HIV increased 26% from 2000 to 2001. This is of major concern to public health workers. AIDS continues to be a problem with illegal sex workers and injection drug users. The death rate has also fallen considerably, as combinations of AIDS treatment drugs (often called "cocktails") have proven to be an effective (if expensive) means of suppressing HIV.

However in Third World countries (especially Sub-Saharan Africa), 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.

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.

Immunity

In 1983, FIV (Feline Immunodeficiency Virus) was discovered by Neils Pederson, doing research on a cat that seemed to be showing AIDS-like symptoms. A close relative of AIDS, it led to an immediate scare that it could spread to a number of wild cat species which are already endangered. Tests for the disease began on various African wild cat species. To the surprise of most involved, the disease was turning up everywhere. The infected wild cat species simply were not showing symptoms like the housecats were. This led to a high level of curiosity as to how the wild species were managing to be infected without this happening.

The initial theories - that the disease was remaining inactive in their systems, that the disease was only present in small amounts, or that the disease wasn't killing the cells that it infected - were all proven wrong. It turned out that the virus was present in huge quantities, and was killing many T-cells. Infected cats from species that didn't show symptoms, however, were simply replacing them as quickly as they were destroyed. It appeared that the wild cat species that were studied had a genetic adaptation to the disease. Housecats, which had not contracted the disease until recently, had no such immunity.

Despite the initial expectation of the researcher, it has since been determined that FIV has no particular relationship to HIV except in its name.

Research in primates has found a variable level of susceptibility to SIV between chimpanzees from different regions of Africa. This has profound implications for research on HIV, not only in ensuring equal natural resistance to the disease amongst laboratory animals. Although SIV and HIV have some similarities, humans can not be infected with SIV, and primates do not get sick from HIV.

In some parts of Africa, HIV infects more than one in every four people.

Prior reports of resistance in humans have proven disappointing in the end: For example, among populations of African prostitutes who were regularly exposed to the virus through unsafe sex practices, some apparently immune individuals were described during the early 1990s and made the subjects of intensive research into mechanisms of natural resistance. However, eventually, each woman in the study became infected with HIV, and no useful data was produced to help with a vaccine.

Similarly, a handful of babies born to HIV+ mothers were described at birth as being HIV+ and later tested negative. Subsequent studies have shown that the testing method was at fault, and these babies never were infected with HIV. The earlier studies checked for antibodies against HIV, not the virus itself, and -- like all other kinds of antibodies in breast-fed babies -- these infants tested positive on the basis of their mothers' antibodies, which had been transmitted to them during feeding.