Speculations on the viral etiology of acquired immune deficiency syndrome and Kaposi's sarcoma.

The acquired immune deficiency syndrome (AIDS) appeared in the United States in late 1978 and has spread at an epidemic rate through the four major coastal cities of this country. The disease appears to show the same epidemiologic distribution as hepatitis B virus infection, and for this reason, most investigators feel that this new disease is caused by a blood-borne sexually transmitted virus. A number of viral agents have been suggested as the cause of AIDS, but to date, no virus has been consistently isolated. The most likely candidate is a retrovirus that has recently been introduced into the human population and has found its way into two extremely high-risk groups, namely, promiscuous male homosexuals and intravenous drug abusers. The relationship between Kaposi's sarcoma and cytomegalovirus is still unclear, but evidence is mounting that cytomegalovirus may be the agent that initiates this multifocal malignancy. Multiple factors must be involved in this process. It is known that some immunosuppressed individuals develop Kaposi's sarcoma, which completely resolves when the immunosuppression is reversed; however, in individuals with classical Kaposi's sarcoma, the profound degree of helper T-cell depression that characterizes the acquired immune deficiency syndrome is not seen.