Resurgence of tuberculosis: the perspective a dozen years later.

More than a dozen years ago, case rates of tuberculosis (TB) began to increase in the United States, as well as in other industrialized and Third World countries. Our US urban centers were the epicenter of the "new" TB epidemic, with New York City accounting for more than 15% of all TB cases in the United States. Numerous factors were responsible for this dramatic, unexpected explosion in mankind's most prevalent and lethal disease, including (1) an increasing pool of susceptible individuals who, by virtue of human immunodeficiency virus (HIV) infection, were much more likely to rapidly progress to active (contagious) TB after becoming infected with Mycobacterium tuberculosis; (2) a reduction in the resources and sites available for the identification, treatment, and surveillance of patients with tuberculous infection and disease; and (3) the importation of TB cases via immigration. Coupled with the resurgence of tuberculosis, new strains of difficult-to-treat, multiple-drug-resistant M tuberculosis (MDRTB) were isolated with increasing frequency, with New York City again the focal point. More than 60% of the nation's MDRTB cases occurred in New York City, reaching a peak of 441 cases in 1992. Over the past 2 years, epidemiologic data suggest that the epidemic has come under control, with a 38% decrease in new cases (1995) compared with the peak year (1992). A number of factors have been important in regaining control of TB, including enhanced diagnostic modalities, such as the use of some molecular biologic strategies; active case and contact finding by public health workers; tailored therapeutic approaches, such as four-drug initial therapy for non-MDRTB, advanced multidrug management for MDRTB, and expanded use of directly observed therapy; and use of personnel-protective devices and environmental controls to decrease nosocomial transmission of TB. These factors are highlighted in this overview article.