The acquired immune deficiency syndrome: an international health problem of increasing importance.

The Acquired Immune Deficiency Syndrome (AIDS) is a new disease which first appeared in human populations about 1979. The disease is defined by the development of unusual types of cancer (e.g. Kaposi's sarcoma), or severe cellular immunodeficiency manifested by opportunistic infections (e.g. Pneumocystis carinii infection), or both. Although the etiology of AIDS is unknown, the epidemiologic evidence is consistent with an infectious agent transmitted by blood (e.g. transfusion, needle sharing) or sexual intercourse. Over three-quarters of the cases have been in homosexual or bisexual males and in intravenous drug abusers; about 5% of cases do not have recognized risk factors. A small number of cases have resulted from transfusion of blood or blood products. The early clinical manifestations are non-specific, and may include asymptomatic skin lesions, dyspnea and dry cough, weight loss, chronic diarrhea, and focal and non-focal central nervous system findings. Treatment for the associated cancers and opportunistic infections may be successful in individual instances, but the underlying immunosuppression of AIDS appears to progress inexorably and the fatality rate approaches 100% within a few years from diagnosis. Although nosocomial transmission has not been documented, infection control guidelines have been developed by analogy with hepatitis B infection.