AIDS

From wipipedia.org
Revision as of 14:08, 30 April 2012 by Leafman (Talk | contribs)

(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to: navigation, search


AIDS (Acquired Immunodeficiency Syndrome or Acquired Immune Deficiency Syndrome, sometimes written Aids) is a human disease characterised by progressive destruction of the body's immune system. It is widely accepted that AIDS results from infection with HIV (Human Immunodeficiency Virus), although a few people reject this view. AIDS is currently considered incurable; where treatments are unavailable (mostly in poorer countries), most sufferers die within a few years of infection. In developed countries, treatment has improved greatly over the past decade, and people have lived with AIDS for ten to twenty years.

It is estimated by the World Health Organisation that as of the end of 2004 37.2 million adults and 2.2 million children were living with HIV. During 2004, 4.9 million people contracted HIV and 3.1 million died from AIDS. Since 1981, AIDS has killed 23.1 million people, out of 79.9 million total infections. In Africa, life expectancy has dropped by decades in many countries solely due to deaths from AIDS and Kaposi's sarcoma, a tumour occurring in AIDS patients that is now the most common tumour reported in sub-Saharan countries.

AIDS was first noticed among gay men and intravenous drug users in the 1980s. By the 1990s there was a global epidemic and in 2004, 58 percent of those with AIDS were women. While gay men and those of African descent continue to suffer higher per capita AIDS rates, the majority of victims are currently heterosexual women and men, and children, in developing countries.

Contents

Symptoms

HIV is transmitted by bodily fluids, such as blood, semen, breast milk, and vaginal secretions. It causes disease by infecting CD4+ helper T cells, a type of white blood cell (or leukocyte) that normally coordinates 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.

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. In fact, there are conflicting accounts between prominent AIDS scientists as to whether the HIV (originally discovered as LAV, lymphadenopathy-associated virus), is sufficient to deplete human T-cell counts. 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. People who remain asymptomatic for 7 to 12 years and maintain a CD4 count of 600+, with no HIV-related illnesses and antiretroviral treatment are often called HIV long-term nonprogressors [1]. 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 8 to 10 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, fully eliminating the HIV virus from those recently exposed, 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. 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.

Research to improve current treatments includes decreasing side effects of current drugs, simplifying drug regimens to improve adherence, and determining the best sequence of regimens to manage drug resistance.

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, 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. 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.

In 2005 the Centers for Disease Control and Prevention in the United States recommended a 28 day HIV drug regimen for those who believe they may have had contact with the virus. The drugs have been shown to be effective in preventing the virus nearly 100% of the time in those who received treatment within the initial 24 hours of exposure. The effectively falls to 52% of the time in those who are treated within 72 hours; those not treated within the first 72 hours are not recommended candidates for the regimen.

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. These theories have been in the field for at least 15 years, and have found little support beyond the original circle of advocates.

Mainstream AIDS activists characterise the position of these dissidents as "AIDS denialism," and believe their public proselytising for their various theories is destructive to the adoption of appropriate preventive and therapeutic measures. Advocates of these theories include elements within some African countries and some gay rights groups, such as ACT-UP in San Francisco. South African president Thabo Mbeki famously made a speech questioning the causal link between AIDS and HIV. 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

AIDS is a global epidemic that exists in every continent. UNAIDS estimates that in 2004, 39.4 million people were infected with AIDS, 3.1 million died due to AIDS (with a total of 19 million dead since 1980) and 4.9 million were newly infected with HIV [2]. The majority of AIDS cases occur in Sub-Saharan Africa, in which 8% of the adult population is infected. South & South East Asia are the second most affected areas, with 15% of global AIDS cases. Children accounted for 500,000 of the AIDS deaths. These numbers have led some experts to call AIDS the deadliest pandemic in human history since the Black Death that ravaged Europe and western Asia in the 14th century and the introduction of smallpox and other Eurasian diseases to the Americas in the 16th century.

In Western countries the infection rate of HIV has slowed somewhat, due to the widespread adoption of safe sex practises by most of the sexually active population (including 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. Even in some major population areas with large gay communities such as San Francisco, United States, AIDS cases have fallen to levels not seen since the original outbreak; many attribute this to aggressive educational campaigns.

In some populations, however, such as young urban gay men of African descent and the African-American community at large, 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 people 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 disillusioned 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 proved 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. 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). 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 Senega 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 Organisation, 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. There are predictions that the infection rate in Russia will continue to rise quickly, since education there about AIDS is almost non-existent. 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, such as abstaining from sexual activity outside a definitely monogamous relation with a seronegative partner, and avoiding blood transfusions with unsafe blood.

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, by sharing cooking and eating utensils, dishes, cups and glasses, hugging and kissing, or by mutual masturbation. 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.

HIV is not a hardy virus; the virus dies within about twenty minutes once it is outside a human body. Thus, for example blood or semen stains quickly become non-infectious and are no cause for concern.

HIV transmission via sexual activity has been recorded from male to male, male to female, female to female and female to male. "Health experts around the world urge people to use condoms to protect themselves from HIV and a host of sexually transmitted infections." [3]. Although condoms are not 100% effective against pregnancy or disease transmission, it has been repeatedly shown that HIV cannot pass through latex condoms. All major brand condoms are electrically tested during production to ensure they have no microscopic holes. However packaged condoms do not last indefinitely, old condoms have a higher risk of tearing, thus they should not be used after the date given on the package.

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 be disposed of. 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 sexual lubricants should not be used with condoms as they can cause tears in the condom material by weakening the latex.

In terms of HIV transmission, oral sex is considered a lower risk than vaginal or anal sex. The relative lack of definitive research on the subject, coupled with conflicting public information and cultural influences have caused many to believe, incorrectly, that oral sex is safe. Although the actual risk factor of oral HIV transmission is unknown, there are documented cases of HIV transmission through both insertive and receptive (male) oral sex. One study concluded that 7.8% of recently infected men in San Francisco were probably infected through oral sex. However, a study of Spanish men who knowingly engaged in oral sex with HIV+ partners identified no cases of oral transmission. Part of the reason for such apparently conflicting evidence is that identifying oral transmission cases is problematic. Most HIV+ persons engaged in other types of sexual activity prior to infection, thus making it difficult or impossible to isolate oral transmission. Factors such as mouth sores, etc., are also difficult to decouple from transmission between "healthy" persons. It is usually recommended not to take semen or preseminal fluid into the mouth. The use of condoms for oral sex (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 sterilised 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.

Several studies have shown that circumcised men may be slightly less likely to contract HIV. Alternatively, there are studies which show nations with high circumcision rates have more AIDS overall than those with low rates. One 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 could be a result of cultural and hygiene differences rather than circumcision. It is unlikely that these findings will lead to an increase in circumcisions carried out on newborns, which are currently performed on most infant boys 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 [4]. 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 than either of these alone.

External links

Smallwikipedialogo.png This page uses content from Wikipedia; the original article can be viewed here.
Personal tools
Namespaces

Variants
Actions
Navigation
Tools