AIDS

Acquired immunodeficiency syndrome
(AIDS)

ICD-10 B24
ICD-9 042

Acquired immunodeficiency syndrome, or acquired immune deficiency syndrome (or acronym AIDS or Aids), is a collection of symptoms and infections resulting from the specific damage to the immune system caused by infection with the human immunodeficiency virus (HIV). It results from the latter stages of advanced HIV infection in humans, thereby leaving compromised individuals prone to opportunistic infections and tumors. Although treatments for both AIDS and HIV exist to slow the virus' progression in a human patient, there is no known cure.

Most researchers believe that HIV originated in sub-Sahara

n Africa during the twentieth century; it is now a global epidemic. UNAIDS and the World Health Organization (WHO) estimate that AIDS has killed more than 25 million people since it was first recognized on December 1, 1981, making it one of the most destructive pandemics in recorded history. In 2005 alone, AIDS claimed between an estimated 2.8 and 3.6 million, of which more than 570,000 were children. In countries where there is access to antiretroviral treatment, both mortality and morbidity of HIV infection have been reduced . However, side-effects of these antiretrovirals have also caused problems such as lipodystrophy, dyslipidaemia, insulin resistance and an increase in cardiovascular risks . T

he difficulty of consistently taking the medicines has also contributed to the rise of viral escape and resistance to the medicines .

Infection by HIV

The Red Ribbon is the global symbol for solidarity with HIV-positive people and those living with AIDS

AIDS is the most severe manifestation of infection with HIV. HIV is a retrovirus that primarily infects vital components of the human immune system such as CD4+ T cells, macrophages and dendritic cells. It also directly and indirectly destroys CD4+ T cells. As CD4+ T cells are required for the proper functioning of the immune syste

m, when enough CD4+ cells have been destroyed by HIV, the immune system barely works, leading to AIDS. Acute HIV infection progresses over time to clinical

latent HIV infection and then to early symptomatic HIV infection and later, to AIDS, which is identified on the basis of the amount of CD4 positive cells in the blood and the presence of certain infections.

In the absence of antiretroviral therapy, progression from HIV infection to AIDS occurs at a median of between nin

e to ten years and the median survival time after developing AIDS is only 9.2 months . However, the rate of clinical disease progression varies widely between individuals, from two weeks up to 20 years. Many factors affect the rate of progression. These include factors that influence the body's ability to defend against HIV, including the infected person's genetic inheritance, general immune function , access to health care, age and other coexisting infections . Differen

t strains of HIV may also cause different rates of clinical disease progression.

Diagnosis

Scanning electron micrograph of HIV-1 budding from cultured lymphocyte

AIDS and HIV case definitions

Since 1981, many different definitions have been developed for epidemiological surveillance such as the Bangui definition and the 1994 expanded World Health Organization AIDS case definition. However, these were never intended to be used for clinical staging of patients, for which they are neither sensitive nor specific. The World H

ealth Organizations (WHO) staging system for HIV infection and disease, using clinical and laboratory data, can be used in developing countries and the Centers for Disease Control (CDC) Classification System can be used in developed nations.

WHO Disease Staging System for HIV Infection and Disease

In 1990, the World Health Organization (WHO) grouped these infections and conditions together by introducing a staging system for patients infected with HIV-1 . This was updated in September 2005. Most of these conditions are opportunistic infections that can be easily treated in healthy people.

• Stage I: HIV disease is asymptomatic and not categorized as AIDS
• Stage II: include minor mucocutaneous manifestations and recurrent upper respiratory tract infections
• Stage III: includes unexplained chronic diarrhea for longer than a month, severe bacterial infections and pulmonary tuberculosis or
• Stage IV includes toxoplasmosis of the brain, candidiasis of the esophagus, trachea, bronchi or lungs and Kaposi's sarcoma; these diseases are used as indicators of AIDS.

CDC Classification System for HIV Infection

In the USA, the definition of AIDS is governed by the Centers for Disease Control and Prevention (CDC). In 1993, the CDC expanded their definition of AIDS to include healthy HIV positive people with a CD4 positive T cell coun

t of less than 200 per µl of blood. The majority of new AIDS cases in the United States are reported on the basis of a low T cell count in the presence of HIV infection

HIV test

Approximately half of those infected with HIV don't know that they are infected until they are diagnosed with AIDS. HIV test kits are used to screen donor blood and blood products, and to diagnose HIV in individuals. Typical HIV tests, including the HIV enzyme immunoassay and the Western blot assay, detect HIV antibodies in serum, plasma, oral fluid, dried blood spot or urine of patients. Other tests to look for HIV antigens, HIV-RNA, and HIV-DNA are also commercially available and can be used to detect HIV infection prior to the development of detectable antibodies. However, these assays are not specifically approved by the U.S. Food and Drug Administration for the diagnosis of HIV infection.

Prevention strategies

Condoms in many colors





During a sexual act, only condoms, be they male or female, can reduce the chances of infection with HIV and other STIs and the chances of becoming pregnant. They must be used during all penetrative sexual intercourse with a partner who is HIV positive or whose status is unknown . The effective use of condoms and s creening of blood transfusion in North America, Western and Central Europe is credited with the low rates of AIDS in these regions.

Promoting condom use, however, has often proved controversial and difficult. Many religious groups, most visibly the Roman Catholic Church, have opposed the use of condoms on religious grounds, and have sometimes seen condom promotion as an affront to the promotion of marriage, monogamy and sexual morality. Other religious groups have argued that preventing HIV infection is a moral task in itself and that condoms are therefore acceptable or even praiseworthy from a religious point of view.

• The male latex condom is the single most efficient available technology to reduce the sexual transmission of HIV and other sexually transmitted infections. In order to be effective, they must be used correctly during each sexual act. Lubricants containing oil, such as petroleum jelly, or butter, must not be used as they weaken latex condoms and make them porous. If necessary, lubricants made from water are recommended. However, it is not recommended to use a lubricant for fellatio. Also, condoms have standards and expiration dates. It is essential to check the expiration date and if it conforms to European (EC 600) or American (D3492) standards before use.

• The female condom is an alternative to the male condom and is made from polyurethane, which allows it to be used in the presence of oil-based lubricants. They are larger than male condoms and have a stiffened ring-shaped opening, and are designed to be inserted into the vagina. The female condom also contains an inner ring which keeps the condom in place inside the vagina - inserting the female condom requires squeezing this ring.

With consistent and correct use of condoms, there is a very low risk of HIV infection. Studies on couples where one partner is infected show that with consistent condom use, HIV infection rates for the uninfected partner are below 1% per year .