Diarrheal disease. Established pathogens, new pathogens, and progress in vaccine development.

Although much progress has been made in reducing the morbidity and mortality of infectious diarrhea through the use of oral rehydration, progress in preventive measures, such as vaccine development, has been slow. Despite the plethora of candidate vaccines developed, there has not been an effective vaccine ready for general use, particularly in developing countries, during the past decade, perhaps in part because of the as-yet-undefined pathophysiology of many of these pathogens, as well as the complexity of the gastrointestinal immune system. It is hoped that more rapid progress will be made during the next decade as our understanding of these factors increases.