Definition

AIDS (Acquired Immune Deficiency Syndrome) is the final and most serious stage of HIV disease, which causes severe damage to the immune system.

According to the Centers for Disease Control and Prevention, AIDS begins when a person with HIV infection has a CD4 cell count below 200. CD4 cells are also called "T-cells" or "helper cells"; they are a type of immune cell. AIDS is also defined by numerous opportunistic infections and cancers that occur in the presence of HIV infection.

Alternative Names

Acquired immune deficiency syndrome

Causes, incidence, and risk factors

AIDS is the fifth leading cause of death among persons between ages 25 and 44 in the United States, down from number one in 1995. About 25 million people worldwide have died from this infection since the start of the epidemic, and 40.3 million people are currently living with HIV/AIDS globally

Human immunodeficiency virus (HIV) causes AIDS. The virus attacks the immune system and leaves the body vulnerable to a variety of life-threatening infections and cancers.

Common bacteria, yeast, parasites, and viruses that ordinarily do not cause serious disease in people with healthy immune systems can cause fatal illnesses in people with AIDS.

HIV has been found in saliva, tears, nervous system tissue and spinal fluid, blood, semen (including pre-seminal fluid), vaginal fluid, and breast milk. However, only blood, semen, vaginal secretions, and breast milk generally transmit infection to others.

Transmission of the virus occurs:

• Through sexual contact -- including oral, vaginal, and anal sex
• Through blood -- via blood transfusions (now extremely rare in the U.S) or needle sharing
• From mother to child -- a pregnant woman can transmit the virus to her fetus through their shared blood circulation, or a nursing mother can transmit it to her baby in her milk

Other transmission methods are rare and include accidental needle injury, artificial insemination with donated semen, and organ transplants.

Worldwide HIV & AIDS Statistics

Global HIV/AIDS estimates, end of 2007

The latest statistics on the world epidemic of HIV and AIDS were published by UNAIDS/WHO in July 2008, and refer to the end of 2007.

More than 25 million people have died of AIDS since 1981.

Africa has 11.6 million AIDS orphans.

At the end of 2007, women accounted for 50% of all adults living with HIV worldwide, and for 59% in sub-Saharan Africa.

Young people (under 25 years old) account for half of all new HIV infections worldwide.

In developing and transitional countries, 9.7 million people are in immediate need of life-saving AIDS drugs; of these, only 2.99 million (31%) are receiving the drugs.More than 25 million people have died of AIDS since 1981.

Africa has 11.6 million AIDS orphans.

At the end of 2007, women accounted for 50% of all adults living with HIV worldwide, and for 59% in sub-Saharan Africa.

Young people (under 25 years old) account for half of all new HIV infections worldwide.

In developing and transitional countries, 9.7 million people are in immediate need of life-saving AIDS drugs; of these, only 2.99 million (31%) are receiving the drugs.

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HIV infection is not spread by casual contact such as hugging, by touching items previously touched by a person infected with the virus, during participation in sports, or by mosquitoes.

It is not transmitted to a person who DONATES blood or organs. Those who donate organs are not in direct contact with those who receive them. Likewise, a person who donates blood is not in contact with the person receiving it. In all these procedures, sterile needles and instruments are used.

However, HIV can be transmitted to a person RECEIVING blood or organs from an infected donor. This is why blood banks and organ donor programs screen donors, blood, and tissues thoroughly.

Those at highest risk include:

• Persons engaging in unprotected sex
• Sexual partners of those who participate in high-risk activities (such as anal sex)
• Intravenous drug users who share needles
• Infants born to mothers with HIV who don't receive HIV therapy during pregnancy
• People who received blood transfusions or clotting products between 1977 and 1985 (prior to the beginning standard screening for the virus in the blood)

AIDS begins with HIV infection. People infected with HIV may have no symptoms for ten years or longer, but they can still transmit the infection to others during this symptom-free period. Meanwhile, if the infection is not detected and treated, the immune system gradually weakens, and AIDS develops.

Acute HIV infection progresses over time to asymptomatic HIV infection and then to early symptomatic HIV infection. Later, it progresses to AIDS (defined as very advanced HIV infection with T-cell count below 200).

Most individuals infected with HIV, if not treated, will develop AIDS. There is a small group of patients who develop AIDS very slowly, or never at all. These patients are called non-progressors, and many seem to have a genetic difference that prevents the virus from attaching to certain immune receptors.

Who is affected by AIDS in America?

Although HIV and AIDS can and do affect all sectors of American society, the impact has been more serious among some groups than others. In the early years of the epidemic, the most commonly identified ‘vulnerable groups’ in America were men who have sex with men, injecting drug users, haemophiliacs and Haitians. Today, AIDS continues to directly affect thousands of gay and bisexual men and injecting drug users every year, but it has also become a serious problem among heterosexual African Americans and, more recently, among the Hispanic/Latino population.

The table below shows how the burden of AIDS among various ethnic groups compares to the percentage of the population that each ethnic group represents.

African Americans: As thetable above shows, African Americans are much disproportionately affected by the AIDS epidemic. To date, black Americans account for 40% of AIDS related deaths. ⁷ The AIDS related deaths of well-known African Americans - such as anchorman Max Robinson, tennis player Arthur Ashe, and rapper Eazy-E - during the 1980s and 90s, increased awareness of the AIDS epidemic among the black community, though there are signs that this level is decreasing. Both men and women are most likely to have become infected through sex with a man, with injecting drug use being the second most likely infection route. Factors such as heightened levels of poverty, lack of access to adequate healthcare, and stigma surrounding men who have sex with men shape the epidemic among African Americans.