prevention, substance-abuse prevention, and pregnancy prevention efforts are likely to reinforce each other. Finally, the community can play a pivotal role in modulating the impact of macroenvironmental factors on the personal environments that shape STD and HIV patterns.
The last 20 years have witnessed six striking changes in patterns of sexually transmitted diseases (STDs): emergence of new STD organisms and etiologies, reemergence of old STDs, shifts in the populations in which STDs are concentrated, shifts in the etiological spectra of STD syndromes, alternations in the incidence of STD complications, and increases in antimicrobial resistance. For example, human immunodeficiency virus (HIV) emerged to devastate the United States with a fatal pandemic involving as many as 1 million people. The incidence of syphilis rose progressively after 1956 to reach a 40-year peak by 1990. In both cases, disease patterns shifted from homosexual men to include minority heterosexuals. Over the last decade, gonorrhea became increasingly concentrated among adolescents, and several new types of antimicrobial resistance appeared. Three interrelated types of environments affect STD patterns. The microbiologic, hormonal, and immunologic microenvironments most directly influence susceptibility, infectiousness, and development of sequelae. These microenvironments are shaped, in part, by the personal environments created by an individual's sexual, substance-use, and health-related behaviors. The personal environments are also important determinants of acquisition of infection and development of sequelae but, in addition, they mediate risk of exposure to infection. These are, therefore, the environments that most directly affect changing disease patterns. Finally, individuals' personal environments are, in turn, molded by powerful macroenvironmental forces, including socioeconomic, demographic, geographic, political, epidemiologic, and technological factors. Over the past 20 years, the profound changes that have occurred in many aspects of the personal environment and the macroenvironment have been reflected in new STD patterns.
I thank Sevgi Aral, Willard Cates, Jr., Ronald Fichtner, Allyn Nakashima, John Ward, and Linda Wright-DeAguero for their valuable input to this article, and Ed Johns and Diane Vitro for their excellent assistance with the figures and tables.
1. Grove, P. B., et al., eds. (1966) Webster's Third New International Unabridged Dictionary (Merriam, Springfield, MA), p. 720.