of tuberculosis in the United States. MMWR 1989;38(No. S‐3):1–25. A Preventing Emerging Infectious Diseases: A Strategy for the 21st Century Overview of the Updated CDC Plan Pathogenic microbes can be resilient, dangerous foes. Although it is impossible to predict their individual emergence in time and place, we can be confident that new microbial diseases will emerge. — Institute of Medicine, Emerging Infections: Microbial Threats to Health in the United States, 1992 Summary Societal, technological, and environmental factors continue to have a dramatic effect on infectious diseases worldwide, facilitating the emergence of new diseases and the reemergence of old ones, sometimes in drug-resistant forms. Modern demographic and ecologic conditions that favor the spread of infectious diseases include rapid population growth; increasing poverty and urban migration; more frequent movement across international boundaries by tourists, workers, immigrants, and refugees; alterations in the habitats of animals and arthropods that transmit disease; increasing numbers of persons with impaired host defenses; and changes in the way that food is processed and distributed. Several recent health events underscore the need for a public health system ready to address whatever disease problems that might arise. For example, in 1997, an avian strain of influenza that had never before infected humans began to kill previously healthy persons in Hong Kong, and strains of Staphylococcus aureus with diminished susceptibility to the antibiotic vancomycin were reported in Japan and the United States. In addition, researchers recently discovered that a strain of the virus that causes acquired immunodeficiency syndrome (AIDS) had been infecting humans for at least 20 years before AIDS emerged as a worldwide epidemic. Preventing Emerging Infectious Diseases: A Strategy for the 21st Century describes CDC’s plan to combat today’s infectious diseases and prevent those of tomorrow. It represents the second phase of the effort launched in 1994 with the publication of CDC’s Addressing Emerging Infectious Disease Threats: A Prevention Strategy for the United States. This overview of the updated plan outlines specific objectives under four major goals: a) surveillance and response, b) applied research, c) infrastructure and training, and d) prevention and control. Achieving these objectives will enhance understanding of infectious diseases and bolster their detection, control, and prevention. The plan also targets nine categories of problems that cause human suffering and place a burden on society. The aim of this plan is to build a stronger, more flexible U.S. public health system that is well-prepared to respond to known disease problems, as well as to address the unexpected, whether it be an influenza pandemic, a disease caused by an unknown organism, or a bioterrorist attack. The implementation of this plan will require the dedicated efforts of many partners, including state and local health departments, other federal agencies, professional societies, universities, research institutes, health-care providers and organizations, the World Vol. 47 / No. RR-15 MMWR 1 Health Organization, and many other domestic and international organizations and groups. INTRODUCTION Infectious diseases are a continuing threat to all persons, regardless of age, sex, lifestyle, ethnic background, and socioeconomic status (1 ). They cause suffering and death and impose a financial burden on society (Table 1) (2–12 ). Although some diseases have been conquered by modern advances such as antibiotics and vaccines, new ones are constantly emerging (e.g., human immunodeficiency virus and acquired immunodeficiency syndrome [HIV/AIDS], Lyme disease, and hantavirus pulmonary syndrome), whereas others reemerge in drug-resistant forms (e.g., malaria, tuberculosis, and bacterial pneumonias). Because no one knows what new diseases will emerge, the public health system must be prepared for the unexpected. For example, in 1997, an avian strain of influenza that had never before attacked humans began to kill previously healthy persons in Hong Kong (13 ). This crisis raised the specter of an influenza pandemic similar to the one that killed 20 million persons in 1918. Also in 1997, strains of Staphylococcus TABLE 1. Annual national costs and charges* associated with some infectious diseases — United States, selected years (1991–1993) Disease Annual cost Type of cost Acquired immunodeficiency syndrome (2 ) $5.8 billion Direct medical charges, (1993 dollars) Tuberculosis (3 ) $703 million Direct medical charges, (1991 dollars) Nosocomial infections (acquired in hospital) (4 ) $4.5 billion Hospital charges (1992 dollars) Foodborne bacteria (5 ) $2.9–$6.7 billion† Direct and indirect costs (1993 dollars) Human papillomavirus (6–10 ) $1.23 billion§ Direct medical charges (1991 dollars) Neonatal group B streptococcal infections (11 ) $294 million Direct medical charges (1993 dollars) Bacterial vaginosis (12 ) $1.0 billion Direct medical charges (1993 dollars) *Costs are actual economic costs whereas charges reflect the amount charged by a health-care provider. †This range is for the combined direct and indirect costs associated with foodborne illnesses caused by six pathogens: Campylobacter jejuni or Campylobacter coli; Clostridium