EFFECT OF CHANGES IN HUMAN-ECOLOGY AND BEHAVIOR ON PATTERNS OF SEXUALLY-TRANSMITTED DISEASES, INCLUDING HUMAN-IMMUNODEFICIENCY-VIRUS INFECTION

The last 20 years have witnessed six striking changes in patterns of s exually transmitted diseases (STDs): emergence of new STD organisms an d etiologies, reemergence of old STDs, shifts in the populations in wh ich STDs are concentrated, shifts in the etiological spectra of STD sy ndromes, alterations in the incidence of STD complications, and increa ses in antimicrobial resistance. For example, human immunodeficiency v irus (HIV) emerged to devastate the United States with a fatal pandemi c involving at least 1 million people. The incidence of syphilis rose progressively after 1956 to reach a 40-year peak by 1990. In both case s, disease patterns shifted from homosexual men to include minority he terosexuals. Over the last decade, gonorrhea became increasingly conce ntrated among adolescents, and several new types of antimicrobial resi stance appeared. Three interrelated types of environments affect STD p atterns. The microbiologic, hormonal, and immunologic microenvironment s most directly influence susceptibility, infectiousness, and developm ent of sequelae. These microenvironments are shaped, in part. by the p ersonal environments created by an individual's sexual, substance-use, and health-related behaviors. The personal environments are also impo rtant determinants of acquisition of infection and development of sequ elae but, in addition, they mediate risk of exposure to infection. The se are. therefore, the environments that most directly affect changing disease patterns. Finally, individuals' personal environments are, in turn, molded by powerful macroenvironmental forces, including socioec onomic, demographic, geographic, political, epidemologic, and technolo gical factors. Over the past 20 years, the profound changes that have occurred in many aspects of the personal environment and the macroenvi ronment have been reflected in new STD patterns.