Acquired immune deficiency syndrome, or AIDS, is a disease entity that has been recognized since 1981. It is caused by infection with the human immunodeficiency virus, which attacks selected cells in the immune system and produces defects in function. 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. Since the first AIDS cases were reported in 1981, through mid-1991, more than 190,000 AIDS cases and more than 120,000 deaths had been reported in about 162 countries worldwide. Sub-Saharan Africa in particular appears to suffer a heavy Berden of this illness. So far there is no cure or vaccine that exists for AIDS, but scientists belive a man by the name of Dr. David Ho has discovered a cure. HIV infection and AIDS represent one of the most pressing public policy and public health problems world wide. Definition of AIDS the U.S Center for disease control has established criteria for defining cases of AIDS that are based on laboratory evidence, the presence of opportunistic diseases, and a range of other conditions. Other complications of HIV infection include fever, diarrhea, severe weight loss, and swollen lymph nodes. 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. Historical Background In the late 1970s, certain rare types of cancer and a veriety of serious infections were recognized to be occurring in increasing

numbers of previously healthy persons. First formally described in 1981, the syndrome was observed predominantly to be affecting homosexual and bisexual men. Soon thereafter, intravenous drug users, hemophiliacs, and recipients of blood transfusions were recognized as being at increased risk for disease as well. Further study of AIDS patients revealed marked depletion of certain white blood cells, called T4 lymphocytes. Then, in 1983, a T-cell lymphotropic virus was separately discovered by Robert Gallo at the U.S National Institutes of Health and Luc Montagnier at France s Pasteur Institute. Modes of Transmission Researchers have isolated HIV from a number of body fluids, including blood, semen, saliva, tears, urine, cerebrospinal fluid, breast milk, and certain cervical and vaginal secretions. Strong evidence indicates, however, that HIV is transmitted only through three primary routes: sexual intercourse, either vaginal or anal, with an infected individual; nondigestive exposure to infected blood or blood products; and from an infected mother to her child before or during birth. At least 97 percent of U.S AIDS cases have been transmitted through one of the routes, with transmission between homosexual men accounting for about 60 percent of AIDS cases. About 21 percent of AIDS cases occur in intravenous drug abusers exposed to HIV infected through sharing needles. The number of new cases of AIDS in reproductive age is increasing at an alarming rate. AIDS has become the leading cause of death for women between the ages of 20 and 40 in major cities of North and South America, Western Europe, and Sub- Saharan Africa.