We live in a global village and do not know what new diseases will arise. We must take every outbreak and every new or re-emerging disease very seriously. We must always be prepared for the unexpected. While we cannot expect to totally prevent the migration of infectious diseases from one part of the world to another, our best efforts should, and do, concentrate on strong surveillance for early detection and response.

Infectious diseases are a continuing menace to all people. Pathogenic organisms can be resilient, dangerous foes. Although it is impossible to predict their individual emergence in time and place, we can be confident that new infectious diseases will emerge. We need to develop, evaluate, and promote strategies to help health care providers change behaviors to prevent disease transmission. And we need a strong and vigilant public health system to respond to the challenge of emerging infectious diseases.