Acquired Immune Deficiency Syndrome (AIDS)

A progressive, degenerative disease involving several major organ systems, including the immune system and central nervous system. Uniformly fatal, it is associated with human immunodeficiency virus (HIV), a viral infection that progressively weakens the immune system.

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Since Acquired Immune Deficiency Syndrome (AIDS) manifests itself in a number of different diseases and conditions, it has been difficult to arrive at a formal definition. In an attempt to standardize the definition of AIDS, the Centers for Disease Control in 1992 included among its diagnostic criteria a count of 200 or fewer CD4T lymphocyte cells per cubic ml of blood (a sign of severe immune system suppression). AIDS was first recognized in 1981 as a cluster of symptoms in homosexual men in New York City and San Francisco. Eventually, similar symptoms were found among intravenous drug users, hemophiliacs, and other recipients of blood transfusions. In 1984, the human immunodeficiency virus (HIV) was isolated and subsequently determined as the probable cause of AIDS.

HIV is transmitted through sexual intercourse, contact with infected blood and blood products, and the birth process. However, casual social contact—even if close and prolonged—has not been found to spread HIV. The greatest number of HIV cases are sexually transmitted, through both homosexual and heterosexual intercourse. Screening of donated blood and blood products since 1985 has drastically reduced the risk of transfusion-related HIV. Children may be infected in utero or by exposure to blood and vaginal secretions during childbirth. The child of an infected mother has a 25 to 35 percent chance of acquiring the virus.

Persons infected with HIV initially show no symptoms. Within three to six weeks after infection they may exhibit flu-like symptoms that last up to three weeks and resolve spontaneously. According to long-term studies, all or almost all persons infected with HIV eventually become ill with full-blown AIDS, although the incubation period varies from less than a year to as long as 15 years. AIDS is considered full-blown when the immune system is seriously suppressed. At this point, the patient becomes vulnerable to opportunistic infections and diseases that are able to attack because of reduced immune system defenses. These include candiasis, pneumocystis carinii pneumonia (PCP), herpes and other viral infections, toxoplasmosis, and tuberculosis. AIDS also weakens the body's defenses against carcinomas, and conditions such as lymphoma and Kaposi's sarcoma are common complications of the disease. AIDS also attacks the nervous system. Neurological disorders such as encephalitis and dementia occur in over two-thirds of AIDS patients. HIV/AIDS patients are also prone to blood abnormalities, respiratory infections, and gastrointestinal problems, including diarrhea, which is partly responsible for the weight loss that occurs in the course of the disease.

Comforting a person with AIDS or any other fatal illness is challenging for friends, family, and others around him. Isolation is one of the most difficult aspects of this disease, often resulting from misinformation and fear about how the disease is spread. There is no scientific evidence that AIDS is spread through casual contact, and there is no reason to avoid gestures of friendship and comfort, such as a personal visit, a hug, or holding the patient's hand.

According to the World Health Organization, an estimated five to ten million people worldwide are infected with HIV. The highest incidence of AIDS is in major cities in Asia, Africa, and the United States. In the United States alone, there are thought to be over one million infected with HIV, and over 250,000 cases of full-blown AIDS have been reported. AIDS has become a leading cause of death in men and women under the age of 45 and children under the age of five. Originally thought of as a "gay men's disease," in 1993 AIDS was the nation's fourth leading cause of death in women between the ages of 15 and 44.

HIV is usually diagnosed through a test called ELISA (enzyme-linked immunosorbent assay), which screens the blood for HIV antibodies. If the test is positive, a more specific test, the Western blot assay, is administered. Most patients will test positive for HIV one to three months after being infected, and 95 percent will test positive after five months. There is no effective vaccine against the HIV virus, and no known cure for AIDS, but antiviral drugs have been effective in slowing the progression of the disease, particularly the suppression of the immune system. One of the earliest of these medications to be effective was azidothymidine (AZT), which inhibits viral DNA polymerase.

The best method of containing the AIDS epidemic is education and prevention. Much of the anti-AIDS effort both in the United States and globally has been directed toward promoting safer sex practices, including abstinence (especially among young people) and the use of latex condoms, which greatly reduce the chance of infection. The threat of HIV among intravenous drug users has been addressed by programs offering education, rehabilitation, and the free dispension of sterile needles. Modification of sexual behavior among homosexuals has been successful in reducing the incidence of new HIV infections among the gay population. However, risk-related behavior is increasing among young homosexuals under the mistaken belief that the threat of AIDS applies mostly to older gay men. Risky sexual behavior has also remained widespread among heterosexual teenagers in the 1990s, especially among African-American and Hispanic males.