AIDS Expository Essay

Acquired immune deficiency syndrome, or AIDS, is a recently recognized disease

entity. It is caused by infection with the human immunodeficiency virus (HIV),

which attacks selected cells in the immune system (see IMMUNITY) and produces

defects in function. These defects may not be apparent for years. They lead in

a relentless fashion, however, to a severe suppression of the immune system's

ability to resist harmful organisms. This leaves the body open to an invasion

by various infections, which are therefore called opportunistic diseases, and to

the development of unusual cancers. The virus also tends to reach certain brain

cells. This leads to so-called neuropsychiatric abnormalities, or psychological

disturbances caused by physical damage to nerve cells. Since the first AIDS

cases were reported in 1981, through mid-1992, more than 190,000 AIDS cases and

more than 152,000 deaths had been reported in the United States alone. This is

only the tip of the iceberg of HIV infection, however. It is estimated that

between 1 million and 1.5 million Americans had been infected with the virus by

the early 1990s but had not yet developed clinical symptoms. In addition,

although the vast majority of documented cases have occurred in the United

States, AIDS cases have been reported in about 162 countries worldwide. Sub-

Saharan Africa in particular appears to suffer a heavy burden of this illness.

No cure or vaccine now exists for AIDS. Many of those infected with HIV may not

even be aware that they carry and can spread the virus. It is evident that HIV

infection represents an epidemic of serious proportions. Combating it is a

major challenge to biomedical scientists and health-care providers. HIV

infection and AIDS represent one of the most pressing public policy and public

health problems worldwide.

Definition of AIDS

The U. S. CENTERS FOR DISEASE CONTROL has established criteria for defining

cases of AIDS that are based on laboratory evidence, the presence of certain

opportunistic diseases, and a range of other conditions. The opportunistic

diseases are generally the most prominent and life-threatening clinical

manifestations of AIDS. It is now recognized, however, that neuropsychiatric

manifestations of HIV infection of the brain are also common. Other

complications of HIV infection include fever, diarrhea, severe weight loss, and

swollen lymph nodes (see LYMPHATIC SYSTEM). When HIV-infected persons experience

some of the above symptoms but do not meet full criteria for AIDS, they are

given the diagnosis of AIDS-related complex, or ARC. The growing feeling is

that asymptomatic HIV infection and ARC should not be viewed as distinct

entities but, rather, as stages of an irreversible progression toward AIDS.

Historical Background

In the late 1970s, certain rare types of cancer and a variety of serious