The challenge and opportunity of new clinical infectious entities.

Abstract

In December 1981, 3 reports of severe opportunistic infections in young homosexual men were published in the same issue of the New England Journal of Medicine [1-3]. David Durak summarized key aspects of the outbreak in an accompanying editorial [4]. Patients were typically young urban homosexual men, the infectious agents were low-grade pathogens associated with opportunistic infections in compromised hosts, and the immune defect was characterized by Tcell lymphocyte depletion. Isolation of opportunistic pathogens from patients in a distinctive population combined with early recognition of the severe character of their immunodeficiency helped guide investigators toward identification and understanding of AIDS. For physicians in the last half of the 20th century, the AIDS epidemic presented challenges of unprecedented urgency and scale, testing our ability to treat desperately ill patients and to reallocate resources in response to changing priorities. At the same time, AIDS was associated with new