A report published by the Centers for Control (CDC) on June 5, 1981, startled the medical community in the United States. This report described five unusual medical cases that had been observed between October, 1980 and May, 1981. All five had developed cases of Pneumocystis carinii pneumonia. P. carinii is a microbe present in the lungs of most healthy people, but can cause sickness when the host immune system has somehow been severely weakened. Immunosuppression in these cases was confirmed by the presence of various other opportunistic infections. Medical authorities were most surprised at the identity of the patients: these cases with severe immune collapse all involved 20-to-40-year-old men, typically considered a healthy age group. Further, all of these men were homosexual. A subsequent report by the CDC on August 28 listed 21 additional cases showing similar severe immune suppression problems. Along with P. carinii pneumonia, esophagal candidiasis (a yeast infection), and other diseases typical of immune deficiencies, a number of these patients displayed a rare condition known as Kaposi's sarcoma. This is a growth in the blood vessel linings, manifesting as reddish lesions on the skin. The CDC referred to these new patients with strange combinations of conditions as "previously healthy homosexual men." Since growing numbers of healthy men should not simultaneously develop severe sickness, the full complement of observed in them was grouped together into a syndrome presumed to have some single underlying cause; first called Gay_related Immune Deficiency (GRID), the syndrome eventually became known as Acquired Immune Deficiency Syndrome, or AIDS. Since this syndrome was first defined, over 130,000 Americans have been diagnosed with AIDS, and over 80,000 of these have died. Male homosexuals continue to comprise the major risk group for AIDS, but intravenous drug users, blood transfusion recipients, and hemophiliacs also have been included as AIDS victims. Since 1981, the list of indicator diseases for diagnosing AIDS has been expanded by the CDC to include P. carinii pneumonia, tuberculosis, Kaposi's sarcoma, dementia, lymphoma, candidiasis, diarrhea-altogether 25 conventional diseases. The most commonly diagnoses of these is P. carinii pneumonia, found in about 53 percent of new AIDS cases last year, followed by wasting syndrome in 19 percent, candidiasis in 13 percent, Kaposi's sarcoma in 11 percent, and dementia in 6 percent.