The Online Encyclopedia and Dictionary







AIDS (Acquired Immunodeficiency Syndrome or Acquired Immune Deficiency Syndrome, sometimes written Aids) is a human disease characterized by progressive destruction of the body's immune system. It is widely accepted that AIDS results from infection with HIV (Human Immunodeficiency Virus), although this hypothesis is not without controversy. HIV infection is a chronic medical condition that can be treated, but not cured. Antiretroviral drugs were widely used to delay, but not prevent progression to AIDS.

UNAIDS and the World Health Organization estimated that between 39 and 44 million people around the world were living with HIV/AIDS in December 2004 (source). It was estimated that during 2004, between 4.3 and 6.4 million people were newly infected with HIV, and AIDS deaths were between 2.8 and 3.5 million.

Since 1981 of an estimated 80 million people with HIV infection wordlwide an estimated 23 million people have died. In Africa, the most common cause of death for people with AIDS is Tuberculosis.

AIDS was first noticed in 1978 among men who had sex with men but widespread knowledge about the disease was not available until the 1980s. By the 1990s the syndrome had become a global pandemic and in 2004, 58 percent of those with AIDS were women. While men who have sex with men and those of African descent have higher per capita AIDS rates, the majority are currently heterosexual women and men, and children in developing countries. Those who have sex without condoms, especially anal intercourse, or do injection drug use are at the highest risk of transmission



The first symptoms of AIDS are opportunistic infections, that do not normally develop in individuals with healthy immune systems. People who have been exposed to HIV are encouraged to have an HIV test, so that the health of their immune system can be monitored and antiretroviral treatment offered before their CD4 cell count is less than 200. The CDC defines the beginning of AIDS as when a person with HIV (human immunodeficiency virus) has either a CD4 cell count below 200 or one of numerous opportunistic infections, which are unusual in a person with a healthy immune system. [1]

The time from infection with HIV to a diagnosis of AIDS varies. A person who has been living with HIV for at least 7 to 12 years and has a stable CD4 cell count above 600, no opportunistic infections, and no previous antiretroviral medication is called a long-term nonprogressor.


HIV is a chronic medical condition that can be treated, but not yet cured. There are effective means of preventing complications and delaying, but not preventing, progression to AIDS.

People with HIV infection need to receive education about the disease and treatment so that they can be active partners in decision making with their health care provider.

The current guidelines for antiretroviral therapy from the World Health Organization reflect the changes to the guidleines to defer retroviral treatment in patients with no symptoms who have a CD4 cell count above 350 and viral load under 100,000.

Antiretroviral regimens are complex, have serious side effects, pose difficulty with adherence, and carry serious potential consequences from the development of viral resistance because of nonadherence to the drug regimen or suboptimal levels of antiretroviral agents. Patient education and involvement in therapeutic decisions are critical. Treatment should usually be offered to all patients with symptoms ascribed to HIV infection. Recommendations for offering antiretroviral therapy among asymptomatic patients require analysis of real and potential risks and benefits. Panel on Clinical Practices for Treatment of HIV. September 2002

HAART (highly-active anti-retroviral therapy) is commonly used to describe a combinations of two or more types of anti-retroviral agents such as two nucleoside analogue reverse transcriptase inhibitors (NRTIs), and a protease inhibitor or a non nucleoside reverse transcriptase inhibitor (NNRTI).

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.

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.


Current strategies to prevent AIDS are directed at the prevention of HIV transmission.

HIV is transmitted through penetrative (anal or vaginal) and oral sex; blood transfusion; the sharing of contaminated needles in health care settings and through drug injection; and, between mother and infant, during pregnancy, childbirth and breastfeeding. UNAIDS transmison

HIV blood screening

WHO estimated in 2000, between 15% and 20% of new HIV infections worldwide were the result of blood transfusions, where the donors were not screened or inadequately screened for HIV. The risk of transmitting HIV infection to blood transfusion recipients has been drastically reduced by improved donor selection and antibody tests in many countries. Antibody tests cannot detect recent HIV infections, because there is a window period of several weeks between infection and the production of antibodies. Antigen and nucleic acid based tests have been introduced in some countries to reduce this window period to 12 days. FDA 2001

Medical procedures

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.

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.

There is an urgent need to address medical transmission as a priority in many countries. see HIV transmission in the medical setting Experts claim health clinics in some countires are the source of up to 30% of HIV tranmission. reference


There is ongoing research into developing a vaccine for HIV. Human trials are currently underway. Gene therapy has also been suggested as a possible approach to preventing or treating HIV infection. VRX496 , a genetic component to suppress HIV (specifically a form of antisense therapy) carried in a modified lentivirus , entered Phase I clinical trials in 2003—the first use of a lentiviral vector in humans. Because of slow progress to date in the development of a vaccine, new approaches are being investigated to encourage industry involvement, including prizes, tax breaks, and advance market commitments.


In 1996, Robert Gallo's discovery that a natural compound known as chemokines can block HIV and halt the progression of AIDS was hailed by Science magazine as one of that year's most important scientific breakthroughs. reference

The role of chemokines in protection from progression of HIV infection to AIDS is changing the medical understanding of AIDS, and may play some future role in treatment or in vaccine development.

Safer sex

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." [2]. 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.

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 [3]. 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.

The Catholic Church promotes abstinence outside of marriage, and lifelong monogamy. [4]

Intravenous drug use

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.

Origins of AIDS

AIDS was first reported as opportunistic infections among gay male intravenous drug users in the 1980s and called GRID (Gay Related Immune Deficiency). Similar opportunistic infections were reported in men with haemophilia and men from Haiti. By the 1990s AIDS cases have been reported around the world in men, women and children. Studies of AIDS in Africa suggest that about half these cases are probably associated with HIV infection.

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. The earliest documented western death from AIDS was Dr. Grethe Rask, a Danish surgeon, who worked in the Congo in the early 1970s.

The controversial OPV AIDS hypothesis argues that the origin of AIDS is the oral polio vaccination programme in Africa during the late 1950s. The first cases of AIDS were discovered in gay men in New York and San Francisco in the late 1970s.

Current medical understanding of AIDS

In January 2005, Anthony S. Fauci, M.D., director of NIAID said, "Individual risk of acquiring HIV and experiencing rapid disease progression is not uniform within populations". NIH press release

Patterns of HIV transmission vary in different parts of the world. In Africa, which accounts for an estimated 60% of new HIV infections worldwide, controversy rages over the respective contribution of medical procedures, heterosexual sex and the bush meat trade. In the United States, sex between men and injecting drug use remain prominent sources of new HIV infections, though the fastest growing group is African-American women. Antiretroviral drugs, cesarean delivery and formula feeding are widely promoted to reduce the transmisison of HIV from mother to child.

Studies have shown that about half the people in Africa defined by WHO criteria as having AIDS are in fact not infected with HIV and therefore may respond to treatment with antibiotics and improved nutrition.

The newly infected person may be highly infectious 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.

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.

Alternative theories

Main article: AIDS reappraisal

The overwhelming scientific consensus is that HIV causes AIDS. However, a few scientists and activists question the connection between HIV and AIDS, or the existence of HIV, or the validity of current testing methods.

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 [5]. 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 practices 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 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). 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 programmes 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 programme 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. 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.

Related diseases

Many opportunistic diseases are associated with AIDS:

See also


External links

The contents of this article are licensed from under the GNU Free Documentation License. How to see transparent copy