CDC's first 50 years: lessons learned and relearned.

This past year at the Centers for Disease Control and Prevention (CDC) has been one of great reflection and re-examination as we have been celebrating, throughout 1996, our 50th anniversary as an agency serving the health of Americans and people all over the world. The anniversary brought both an opportunity to look back at the public health events in which CDC has played a part during the past half-century and a new, symbolic starting point for projections about CDC's work during the 21st century. Growing out of a malaria control program during World War II, CDC has evolved into an agency encompassing many issues across the spectrum of human health: the Epidemic Intelligence Service, a cadre of outstanding "shoe leather" disease detectives sent regularly to investigate disease outbreaks where they occur; the smallpox eradication effort that ended in 1977 in Somalia and, now, the effort to eradicate polio by the year 2000; Legionnaire's disease, toxic shock, and acquired immunodeficiency syndrome (AIDS); hantavirus, Ebola, and other emerging infectious diseases; lead poisoning control and other environmental and workplace health measures; and many newer programs to reduce chronic diseases such as diabetes, as well as other conditions and congenital defects such as spina bifida, which we now know often can be prevented with folic acid intake in the periconceptional period. Besides battling emerging diseases, CDC currently has been called upon to resume and lead the fight against resurgent infections such as malaria, tuberculosis, and cholera. After 30 years of decline in tuberculosis cases in this country (from 1955 to 1985), we saw a steady increase during the following 8 years. Major factors in the resurgence of tuberculosis are social and economic, such as drug abuse and homelessness. The effort to reduce tuberculosis has been complicated by yet another source of great concern in public health, namely, the emergence of antibiotic-resistant organisms. New strategies for controlling tuberculosis have been implemented, including directly observed therapy, and we are now again witnessing a decline in tuberculosis. Over these 50 years CDC increasingly has confronted public health challenges that originate in human behavior. Research into behavior and the development of effective programs to help citizens change behavior have become integral to CDC efforts. These aim to prevent and reduce injury and violence, to achieve and maintain levels of physical activity to support better health, and to prevent and control the spread of diseases such as AIDS. Thus, CDC has enlarged its scope. Its charge has evolved from identifying agents of disease that can be contained in a test tube and treated with the contents of another test tube, to identifying the elusive patterns and origins of human behaviors that so frequently result in adverse health consequences. Newly emerging and reemerging infectious diseases, too, often involve complex human and environmental factors requiring new approaches for control. Many prevention and treatment programs, therefore, have undergone substantial shifts to reflect this principle. In a traditional laboratory, the means are unlikely to be found either to prevent the initiation of such behaviors, or