It is well to remember that AIDS is actually the final stage, the most severe end stage, of infection with what we know as the AIDS virus. AIDS is also generally accepted as a syndrome, a collection of specific, life-threatening opportunistic infections and symptoms that is the result of an underlying immune deficiency -- a deficiency not caused by any known conditions and illnesses other than infection with the AIDS virus. The acquired immune deficiency itself -- the "AID" part of AIDS -- does not kill. It destroys the body's capacity to ward off bacteria and viruses that would ordinarily be fought off by a properly functioning immune system, and it is the diseases, the opportunistic infections, caused by these outside agents that eventually kill the victim; or, death results from a form of cancer, Kaposi's sarcoma, that is far more aggressive in AIDS patients than among those who do not suffer from AIDS. Thus, one can say that AIDS killed the person, since the addition of the "S" defines a syndrome: the collection of diseases and symptoms that resulted from the weakened immune system. Putting it another way, one can say that the AIDS virus itself does not kill, nor does it generally cause the various diseases associated with the syndrome; most of the disastrous events are simply the result of the damage to the immune system. Nor does infection with the virus mean that a person has AIDS at that moment. It means that the virus has gained entry into that person's body. When the first half dozen U.S. cases of AIDS were reported in Los Angeles in 1981, scientists at the Centers for Disease Control were convinced they were looking at a new disease because they had never seen anything destroy an immune system so fast. But as the epidemic grew, they started changing their minds. It now appeared that AIDS was new only to the Western world, that it had originated in central Africa, and that the virus that caused it was perhaps an evolutionary descendant of one that had existed in monkeys for as long as 50,000 years, one that had mutated enough to enable it to jump species fairly recently and infect human cells.