infections have been documented, as have vancomycin-resistant staphylococcal and enterococcal infections. Without more careful prescription of antimicrobials by physicians and more consistent compliance with treatment regimens by patients, pathogenic bacteria are likely to undergo mutations that will enable them to resist available antibiotic therapy.

It is unrealistic to expect that humankind will win a complete victory over the multitude of existing microbial diseases, or over those that will emerge in the future. This will be true no matter how well stocked our armamentaria of drugs and vaccines, no matter how well planned our efforts to prevent and control epidemics, and no matter how advanced our basic science and clinical understanding of infectious diseases. Microbes are ranked among the most numerous and diverse of organisms on the planet; 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.

Still, there are many steps that scientists, educators, public health officials, policymakers, and others can and should be taking to improve our odds in this ongoing struggle. With diligence and concerted action at many levels, the threats posed by emerging infectious diseases can be, if not eliminated, at least significantly moderated. To achieve this goal, however, a number of fundamental problems must be addressed. These problems fall into four broad categories:

• Perceiving the Threats: The emergence of HIV disease has stimulated a high level of interest in the scientific, medical, public health, and policymaking communities. By and large, however, awareness of and concern about the threats to human health posed by other emerging and reemerging microbial diseases remain critically low. A small minority, mainly infectious disease specialists, have for years warned of the potential for serious epidemics and our lack of preparedness for them. In what can only be called a general mood of complacency, these warnings have gone largely unheeded.

• Detecting the Threats: Surveillance is the primary means by which the incidence of established diseases is monitored and outbreaks of new diseases are detected. The domestic disease surveillance network in the United States is being scaled back as a result of fiscal problems in many states, raising concerns about its ability to perform a vital public health function. Equally worrisome, the existing international surveillance networks are focused on little more than a handful of well-defined diseases, and U.S. involvement in this worldwide effort is diminishing. Epidemiological